PTCB Drug Suffixes: 87 Stems Checked Against the Official Lists
These are the drug suffixes worth knowing for the PTCB exam (the PTCE): official name stems that tell you a drug's family, like -pril for ACE inhibitors and -olol for beta blockers. PTCB doesn't publish its own suffix list, so every stem below comes from the U.S. (USAN) and WHO naming lists, with examples we checked.
Original, unofficial study material by the Castleport Test Prep Editorial Team · Last verified September 24, 2026
101 study items shown.
The drug suffix list (87 stems)
Heart and blood (17)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 1 | -pril | Angiotensin-converting enzyme inhibitors | ACE inhibitor | enalapril, lisinopril | -prilat is the same family (enalaprilat). | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: lisinopril |
| 2 | -sartan | Angiotensin II receptor antagonists | ARB (angiotensin II receptor blocker) | losartan, valsartan (Diovan) | WHO stem book · AMA naming guidelines · USAN stem list (earlier copy) | |
| 3 | -olol | Beta-adrenoreceptor antagonists | Beta blocker | atenolol, timolol, metoprolol | Not every beta blocker ends in -olol. See -alol and the carvedilol trap. | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: metoprolol |
| 4 | -alol | Related to the -olols; the USAN list calls them combined alpha and beta blockers | Alpha/beta blocker | labetalol | WHO stem book · USAN stem list (earlier copy) | |
| 5 | -dipine | Calcium channel blockers, nifedipine type | Calcium channel blocker | nifedipine, felodipine, amlodipine | Not every calcium channel blocker ends in -dipine (see -tiazem and -pamil). | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: amlodipine |
| 6 | -tiazem | Calcium channel blockers, diltiazem type | Calcium channel blocker | diltiazem | WHO stem book · USAN stem list (earlier copy) | |
| 7 | -pamil | Calcium channel blockers, verapamil type | Calcium channel blocker | verapamil | WHO stem book | |
| 8 | -vastatin (taught as "-statin") | HMG-CoA reductase inhibitors, a subgroup of the broader -stat (enzyme inhibitor) stem | Statin | atorvastatin (Lipitor), rosuvastatin (Crestor), lovastatin, pravastatin | Nystatin is not a statin. It is a polyene antifungal. | WHO stem book · AMA naming guidelines · USAN stem list (earlier copy) · MedlinePlus: nystatin |
| 9 | -semide | Diuretics, furosemide type | Diuretic | furosemide | Bumetanide uses a different stem (-etanide). | WHO stem book |
| 10 | -etanide | Diuretics, piretanide type | Diuretic | bumetanide | WHO stem book | |
| 11 | -thiazide (WHO spelling: -tizide) | Diuretics, chlorothiazide type | Thiazide diuretic | chlorothiazide | WHO stem book · USAN stem list (earlier copy) | |
| 12 | -azosin | Antihypertensives, prazosin type | Prazosin-type antihypertensive | doxazosin, prazosin, terazosin | WHO lists tamsulosin and alfuzosin as related drugs that do not carry this stem. | WHO stem book |
| 13 | -parin / -parinux | Heparin derivatives, including low-molecular-weight heparins; -parinux means synthetic heparinoids | Heparin-type anticoagulant | heparin, dalteparin, tinzaparin; fondaparinux | WHO stem book · USAN stem list (earlier copy) | |
| 14 | -xaban | Blood coagulation factor Xa inhibitors | Factor Xa inhibitor | apixaban | WHO stem book · MedlinePlus: apixaban | |
| 15 | -grel | Platelet aggregation inhibitors | Antiplatelet | clopidogrel (Plavix) | WHO stem book · AMA naming guidelines · MedlinePlus: clopidogrel | |
| 16 | -afil | PDE5 inhibitors with a vasodilator action | PDE-5 inhibitor | sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra) | WHO stem book · AMA naming guidelines | |
| 17 | -arone | The USAN list defines it as antiarrhythmics | Antiarrhythmic | amiodarone, dronedarone | WHO's listing also shows -arone on some drugs that are not antiarrhythmics, such as benzbromarone. | WHO stem book · AMA naming guidelines |
#1 · Heart and blood
-pril
- Official meaning
- Angiotensin-converting enzyme inhibitors
- Call it
- ACE inhibitor
- Examples
- enalapril, lisinopril
- Watch out
- -prilat is the same family (enalaprilat).
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: lisinopril
#2 · Heart and blood
-sartan
- Official meaning
- Angiotensin II receptor antagonists
- Call it
- ARB (angiotensin II receptor blocker)
- Examples
- losartan, valsartan (Diovan)
- Watch out
- Sources
- WHO stem book · AMA naming guidelines · USAN stem list (earlier copy)
#3 · Heart and blood
-olol
- Official meaning
- Beta-adrenoreceptor antagonists
- Call it
- Beta blocker
- Examples
- atenolol, timolol, metoprolol
- Watch out
- Not every beta blocker ends in -olol. See -alol and the carvedilol trap.
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: metoprolol
#4 · Heart and blood
-alol
- Official meaning
- Related to the -olols; the USAN list calls them combined alpha and beta blockers
- Call it
- Alpha/beta blocker
- Examples
- labetalol
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#5 · Heart and blood
-dipine
- Official meaning
- Calcium channel blockers, nifedipine type
- Call it
- Calcium channel blocker
- Examples
- nifedipine, felodipine, amlodipine
- Watch out
- Not every calcium channel blocker ends in -dipine (see -tiazem and -pamil).
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: amlodipine
#6 · Heart and blood
-tiazem
- Official meaning
- Calcium channel blockers, diltiazem type
- Call it
- Calcium channel blocker
- Examples
- diltiazem
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#7 · Heart and blood
-pamil
- Official meaning
- Calcium channel blockers, verapamil type
- Call it
- Calcium channel blocker
- Examples
- verapamil
- Watch out
- Sources
- WHO stem book
#8 · Heart and blood
-vastatin (taught as "-statin")
- Official meaning
- HMG-CoA reductase inhibitors, a subgroup of the broader -stat (enzyme inhibitor) stem
- Call it
- Statin
- Examples
- atorvastatin (Lipitor), rosuvastatin (Crestor), lovastatin, pravastatin
- Watch out
- Nystatin is not a statin. It is a polyene antifungal.
- Sources
- WHO stem book · AMA naming guidelines · USAN stem list (earlier copy) · MedlinePlus: nystatin
#9 · Heart and blood
-semide
- Official meaning
- Diuretics, furosemide type
- Call it
- Diuretic
- Examples
- furosemide
- Watch out
- Bumetanide uses a different stem (-etanide).
- Sources
- WHO stem book
#10 · Heart and blood
-etanide
- Official meaning
- Diuretics, piretanide type
- Call it
- Diuretic
- Examples
- bumetanide
- Watch out
- Sources
- WHO stem book
#11 · Heart and blood
-thiazide (WHO spelling: -tizide)
- Official meaning
- Diuretics, chlorothiazide type
- Call it
- Thiazide diuretic
- Examples
- chlorothiazide
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#12 · Heart and blood
-azosin
- Official meaning
- Antihypertensives, prazosin type
- Call it
- Prazosin-type antihypertensive
- Examples
- doxazosin, prazosin, terazosin
- Watch out
- WHO lists tamsulosin and alfuzosin as related drugs that do not carry this stem.
- Sources
- WHO stem book
#13 · Heart and blood
-parin / -parinux
- Official meaning
- Heparin derivatives, including low-molecular-weight heparins; -parinux means synthetic heparinoids
- Call it
- Heparin-type anticoagulant
- Examples
- heparin, dalteparin, tinzaparin; fondaparinux
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#14 · Heart and blood
-xaban
- Official meaning
- Blood coagulation factor Xa inhibitors
- Call it
- Factor Xa inhibitor
- Examples
- apixaban
- Watch out
- Sources
- WHO stem book · MedlinePlus: apixaban
#15 · Heart and blood
-grel
- Official meaning
- Platelet aggregation inhibitors
- Call it
- Antiplatelet
- Examples
- clopidogrel (Plavix)
- Watch out
- Sources
- WHO stem book · AMA naming guidelines · MedlinePlus: clopidogrel
#16 · Heart and blood
-afil
- Official meaning
- PDE5 inhibitors with a vasodilator action
- Call it
- PDE-5 inhibitor
- Examples
- sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra)
- Watch out
- Sources
- WHO stem book · AMA naming guidelines
#17 · Heart and blood
-arone
- Official meaning
- The USAN list defines it as antiarrhythmics
- Call it
- Antiarrhythmic
- Examples
- amiodarone, dronedarone
- Watch out
- WHO's listing also shows -arone on some drugs that are not antiarrhythmics, such as benzbromarone.
- Sources
- WHO stem book · AMA naming guidelines
Infections (17)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 18 | -cillin | Penicillins (6-aminopenicillanic acid derivatives) | Penicillin | amoxicillin, ampicillin, dicloxacillin, piperacillin | WHO stem book | |
| 19 | cef- (prefix) | Cephalosporins | Cephalosporin | cefazolin, cefdinir, ceftriaxone, cefuroxime | Cefazolin ends like -azoline, but the cef- prefix decides the family. | WHO stem book |
| 20 | -bactam | Beta-lactamase inhibitors | Beta-lactamase inhibitor | sulbactam, tazobactam | Clavulanic acid is in the same group without the stem. | WHO stem book |
| 21 | -cycline | Tetracycline derivatives (protein-synthesis inhibitors) | Tetracycline | minocycline | WHO stem book · USAN stem list (earlier copy) | |
| 22 | -oxacin (often taught as "-floxacin") | Quinolone antibacterials (nalidixic acid derivatives) | Fluoroquinolone | ciprofloxacin | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: ciprofloxacin | |
| 23 | -mycin | Antibiotics produced by Streptomyces strains. This names a source, not one drug class. | Check the drug | lincomycin; azithromycin (macrolide); clindamycin (lincomycin antibiotic); vancomycin (glycopeptide) | The biggest trap on this list. | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: azithromycin · MedlinePlus: clindamycin · MedlinePlus: vancomycin |
| 24 | -micin | Aminoglycosides obtained from Micromonospora | Aminoglycoside | gentamicin | -micin and -mycin are different stems. | WHO stem book · USAN stem list (earlier copy) |
| 25 | -conazole | Systemic antifungals, miconazole type | Azole antifungal | fluconazole, ketoconazole, itraconazole, voriconazole, miconazole | Only -conazole means this. Not every -azole is an antifungal. | WHO stem book |
| 26 | -nidazole | Antiprotozoals, metronidazole type | Antiprotozoal (metronidazole type) | metronidazole, tinidazole | Not an antifungal. | WHO stem book · USAN stem list (earlier copy) |
| 27 | sulfa- (prefix) | Sulfonamide anti-infectives | Sulfonamide | sulfasalazine | WHO stem book · USAN stem list (earlier copy) | |
| 28 | -zolid | Oxazolidinone antibacterials | Oxazolidinone | linezolid | WHO stem book · USAN stem list (earlier copy) | |
| 29 | -ciclovir / -cyclovir | Antivirals related in structure to acyclovir | Antiviral (acyclovir type) | acyclovir, ganciclovir, valacyclovir (Valtrex) | WHO stem book · AMA naming guidelines · USAN stem list (earlier copy) | |
| 30 | -amivir | Neuraminidase inhibitors | Neuraminidase inhibitor | zanamivir | WHO stem book · USAN stem list (earlier copy) | |
| 31 | -navir | HIV protease inhibitors | HIV protease inhibitor | ritonavir, indinavir | WHO stem book · USAN stem list (earlier copy) | |
| 32 | -tegravir | HIV integrase inhibitors | Integrase inhibitor | elvitegravir | WHO stem book · USAN stem list (earlier copy) | |
| 33 | -vudine | Uridine-type antivirals and antineoplastics (zidovudine group) | Nucleoside antiviral | lamivudine, stavudine | WHO stem book · USAN stem list (earlier copy) | |
| 34 | -citabine | Nucleoside antivirals or antineoplastics | Nucleoside analog | emtricitabine, gemcitabine | Same ending, two very different uses. | WHO stem book |
#18 · Infections
-cillin
- Official meaning
- Penicillins (6-aminopenicillanic acid derivatives)
- Call it
- Penicillin
- Examples
- amoxicillin, ampicillin, dicloxacillin, piperacillin
- Watch out
- Sources
- WHO stem book
#19 · Infections
cef- (prefix)
- Official meaning
- Cephalosporins
- Call it
- Cephalosporin
- Examples
- cefazolin, cefdinir, ceftriaxone, cefuroxime
- Watch out
- Cefazolin ends like -azoline, but the cef- prefix decides the family.
- Sources
- WHO stem book
#20 · Infections
-bactam
- Official meaning
- Beta-lactamase inhibitors
- Call it
- Beta-lactamase inhibitor
- Examples
- sulbactam, tazobactam
- Watch out
- Clavulanic acid is in the same group without the stem.
- Sources
- WHO stem book
#21 · Infections
-cycline
- Official meaning
- Tetracycline derivatives (protein-synthesis inhibitors)
- Call it
- Tetracycline
- Examples
- minocycline
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#22 · Infections
-oxacin (often taught as "-floxacin")
- Official meaning
- Quinolone antibacterials (nalidixic acid derivatives)
- Call it
- Fluoroquinolone
- Examples
- ciprofloxacin
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: ciprofloxacin
#23 · Infections
-mycin
- Official meaning
- Antibiotics produced by Streptomyces strains. This names a source, not one drug class.
- Call it
- Check the drug
- Examples
- lincomycin; azithromycin (macrolide); clindamycin (lincomycin antibiotic); vancomycin (glycopeptide)
- Watch out
- The biggest trap on this list.
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: azithromycin · MedlinePlus: clindamycin · MedlinePlus: vancomycin
#24 · Infections
-micin
- Official meaning
- Aminoglycosides obtained from Micromonospora
- Call it
- Aminoglycoside
- Examples
- gentamicin
- Watch out
- -micin and -mycin are different stems.
- Sources
- WHO stem book · USAN stem list (earlier copy)
#25 · Infections
-conazole
- Official meaning
- Systemic antifungals, miconazole type
- Call it
- Azole antifungal
- Examples
- fluconazole, ketoconazole, itraconazole, voriconazole, miconazole
- Watch out
- Only -conazole means this. Not every -azole is an antifungal.
- Sources
- WHO stem book
#26 · Infections
-nidazole
- Official meaning
- Antiprotozoals, metronidazole type
- Call it
- Antiprotozoal (metronidazole type)
- Examples
- metronidazole, tinidazole
- Watch out
- Not an antifungal.
- Sources
- WHO stem book · USAN stem list (earlier copy)
#27 · Infections
sulfa- (prefix)
- Official meaning
- Sulfonamide anti-infectives
- Call it
- Sulfonamide
- Examples
- sulfasalazine
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#28 · Infections
-zolid
- Official meaning
- Oxazolidinone antibacterials
- Call it
- Oxazolidinone
- Examples
- linezolid
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#29 · Infections
-ciclovir / -cyclovir
- Official meaning
- Antivirals related in structure to acyclovir
- Call it
- Antiviral (acyclovir type)
- Examples
- acyclovir, ganciclovir, valacyclovir (Valtrex)
- Watch out
- Sources
- WHO stem book · AMA naming guidelines · USAN stem list (earlier copy)
#30 · Infections
-amivir
- Official meaning
- Neuraminidase inhibitors
- Call it
- Neuraminidase inhibitor
- Examples
- zanamivir
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#31 · Infections
-navir
- Official meaning
- HIV protease inhibitors
- Call it
- HIV protease inhibitor
- Examples
- ritonavir, indinavir
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#32 · Infections
-tegravir
- Official meaning
- HIV integrase inhibitors
- Call it
- Integrase inhibitor
- Examples
- elvitegravir
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#33 · Infections
-vudine
- Official meaning
- Uridine-type antivirals and antineoplastics (zidovudine group)
- Call it
- Nucleoside antiviral
- Examples
- lamivudine, stavudine
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#34 · Infections
-citabine
- Official meaning
- Nucleoside antivirals or antineoplastics
- Call it
- Nucleoside analog
- Examples
- emtricitabine, gemcitabine
- Watch out
- Same ending, two very different uses.
- Sources
- WHO stem book
Brain, mood, sleep and nerves (18)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 35 | -azepam | Diazepam derivatives | Benzodiazepine | diazepam, lorazepam, clonazepam, temazepam | WHO stem book | |
| 36 | -azolam | Filed by WHO with -azepam (diazepam derivatives) | Benzodiazepine | alprazolam, midazolam, triazolam | Two endings, one family. | WHO stem book |
| 37 | -pidem | Hypnotics and sedatives, zolpidem type | Sedative-hypnotic | zolpidem | Not a benzodiazepine stem. | WHO stem book · USAN stem list (earlier copy) |
| 38 | -plon | Imidazopyrimidine or pyrazolopyrimidine anxiolytics, sedatives and hypnotics | Sedative-hypnotic | zaleplon | WHO stem book · USAN stem list (earlier copy) | |
| 39 | -clone | Hypnotic tranquilizers (zopiclone type) | Sedative-hypnotic | eszopiclone | WHO stem book | |
| 40 | barb (-barbital) | Barbituric acid derivatives | Barbiturate | phenobarbital, pentobarbital, secobarbital | WHO lists butalbital in the same group without the stem. | WHO stem book |
| 41 | -oxetine | Serotonin and/or norepinephrine reuptake inhibitors related to fluoxetine | Antidepressant (fluoxetine family) | fluoxetine, duloxetine (Cymbalta) | Covers more than one reuptake mechanism. | WHO stem book · AMA naming guidelines |
| 42 | -traline | Serotonin reuptake inhibitors | SSRI (selective serotonin reuptake inhibitor) | sertraline | Escitalopram is an SSRI with neither -traline nor -oxetine. | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: escitalopram |
| 43 | -faxine | The USAN Council defines it as antianxiety and antidepressant reuptake inhibitors | Antidepressant | venlafaxine (Effexor XR) | A U.S. (USAN) stem; it is not in WHO's 2018 list. | AMA naming guidelines |
| 44 | -triptyline | Antidepressants, dibenzocycloheptane type (WHO files it with the tricyclics) | Tricyclic antidepressant | amitriptyline | WHO stem book · USAN stem list (earlier copy) | |
| 45 | -pramine | Imipramine group (WHO files it with the tricyclics) | Tricyclic antidepressant | imipramine | WHO stem book | |
| 46 | -peridone | Antipsychotics, risperidone type | Antipsychotic | risperidone, iloperidone | WHO stem book · USAN stem list (earlier copy) | |
| 47 | -peridol | Antipsychotics, haloperidol type | Antipsychotic | haloperidol | WHO stem book · USAN stem list (earlier copy) | |
| 48 | -spirone | Anxiolytics, buspirone type | Anxiolytic | buspirone | WHO stem book | |
| 49 | -triptan | Serotonin 5-HT1 receptor agonists, sumatriptan type (the USAN list says antimigraine agents) | Triptan | sumatriptan, naratriptan | Not the same as -setron. | WHO stem book · USAN stem list (earlier copy) |
| 50 | -caine | Local anesthetics | Local anesthetic | lidocaine, benzocaine, bupivacaine, tetracaine | "-cain-" inside a name (procainamide, flecainide) marks class I antiarrhythmics. | WHO stem book |
| 51 | -dopa | Dopamine receptor agonists and dopamine derivatives used for parkinsonism | Dopaminergic (antiparkinson) | levodopa | WHO stem book · USAN stem list (earlier copy) | |
| 52 | -pezil | The USAN list defines it as acetylcholinesterase inhibitors used in Alzheimer's disease | Cholinesterase inhibitor | donepezil | A U.S. (USAN) stem; it is not in WHO's 2018 list. | USAN stem list (earlier copy) |
#35 · Brain, mood, sleep and nerves
-azepam
- Official meaning
- Diazepam derivatives
- Call it
- Benzodiazepine
- Examples
- diazepam, lorazepam, clonazepam, temazepam
- Watch out
- Sources
- WHO stem book
#36 · Brain, mood, sleep and nerves
-azolam
- Official meaning
- Filed by WHO with -azepam (diazepam derivatives)
- Call it
- Benzodiazepine
- Examples
- alprazolam, midazolam, triazolam
- Watch out
- Two endings, one family.
- Sources
- WHO stem book
#37 · Brain, mood, sleep and nerves
-pidem
- Official meaning
- Hypnotics and sedatives, zolpidem type
- Call it
- Sedative-hypnotic
- Examples
- zolpidem
- Watch out
- Not a benzodiazepine stem.
- Sources
- WHO stem book · USAN stem list (earlier copy)
#38 · Brain, mood, sleep and nerves
-plon
- Official meaning
- Imidazopyrimidine or pyrazolopyrimidine anxiolytics, sedatives and hypnotics
- Call it
- Sedative-hypnotic
- Examples
- zaleplon
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#39 · Brain, mood, sleep and nerves
-clone
- Official meaning
- Hypnotic tranquilizers (zopiclone type)
- Call it
- Sedative-hypnotic
- Examples
- eszopiclone
- Watch out
- Sources
- WHO stem book
#40 · Brain, mood, sleep and nerves
barb (-barbital)
- Official meaning
- Barbituric acid derivatives
- Call it
- Barbiturate
- Examples
- phenobarbital, pentobarbital, secobarbital
- Watch out
- WHO lists butalbital in the same group without the stem.
- Sources
- WHO stem book
#41 · Brain, mood, sleep and nerves
-oxetine
- Official meaning
- Serotonin and/or norepinephrine reuptake inhibitors related to fluoxetine
- Call it
- Antidepressant (fluoxetine family)
- Examples
- fluoxetine, duloxetine (Cymbalta)
- Watch out
- Covers more than one reuptake mechanism.
- Sources
- WHO stem book · AMA naming guidelines
#42 · Brain, mood, sleep and nerves
-traline
- Official meaning
- Serotonin reuptake inhibitors
- Call it
- SSRI (selective serotonin reuptake inhibitor)
- Examples
- sertraline
- Watch out
- Escitalopram is an SSRI with neither -traline nor -oxetine.
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: escitalopram
#43 · Brain, mood, sleep and nerves
-faxine
- Official meaning
- The USAN Council defines it as antianxiety and antidepressant reuptake inhibitors
- Call it
- Antidepressant
- Examples
- venlafaxine (Effexor XR)
- Watch out
- A U.S. (USAN) stem; it is not in WHO's 2018 list.
- Sources
- AMA naming guidelines
#44 · Brain, mood, sleep and nerves
-triptyline
- Official meaning
- Antidepressants, dibenzocycloheptane type (WHO files it with the tricyclics)
- Call it
- Tricyclic antidepressant
- Examples
- amitriptyline
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#45 · Brain, mood, sleep and nerves
-pramine
- Official meaning
- Imipramine group (WHO files it with the tricyclics)
- Call it
- Tricyclic antidepressant
- Examples
- imipramine
- Watch out
- Sources
- WHO stem book
#46 · Brain, mood, sleep and nerves
-peridone
- Official meaning
- Antipsychotics, risperidone type
- Call it
- Antipsychotic
- Examples
- risperidone, iloperidone
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#47 · Brain, mood, sleep and nerves
-peridol
- Official meaning
- Antipsychotics, haloperidol type
- Call it
- Antipsychotic
- Examples
- haloperidol
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#48 · Brain, mood, sleep and nerves
-spirone
- Official meaning
- Anxiolytics, buspirone type
- Call it
- Anxiolytic
- Examples
- buspirone
- Watch out
- Sources
- WHO stem book
#49 · Brain, mood, sleep and nerves
-triptan
- Official meaning
- Serotonin 5-HT1 receptor agonists, sumatriptan type (the USAN list says antimigraine agents)
- Call it
- Triptan
- Examples
- sumatriptan, naratriptan
- Watch out
- Not the same as -setron.
- Sources
- WHO stem book · USAN stem list (earlier copy)
#50 · Brain, mood, sleep and nerves
-caine
- Official meaning
- Local anesthetics
- Call it
- Local anesthetic
- Examples
- lidocaine, benzocaine, bupivacaine, tetracaine
- Watch out
- "-cain-" inside a name (procainamide, flecainide) marks class I antiarrhythmics.
- Sources
- WHO stem book
#51 · Brain, mood, sleep and nerves
-dopa
- Official meaning
- Dopamine receptor agonists and dopamine derivatives used for parkinsonism
- Call it
- Dopaminergic (antiparkinson)
- Examples
- levodopa
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#52 · Brain, mood, sleep and nerves
-pezil
- Official meaning
- The USAN list defines it as acetylcholinesterase inhibitors used in Alzheimer's disease
- Call it
- Cholinesterase inhibitor
- Examples
- donepezil
- Watch out
- A U.S. (USAN) stem; it is not in WHO's 2018 list.
- Sources
- USAN stem list (earlier copy)
Stomach and gut (3)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 53 | -prazole | Antiulcer agents of the benzimidazole type (the AMA says agents for ulcer and/or heartburn) | PPI (proton pump inhibitor) | omeprazole (Prilosec), lansoprazole (Prevacid) | Aripiprazole looks similar but is an antipsychotic (see traps). | WHO stem book · AMA naming guidelines · MedlinePlus: omeprazole |
| 54 | -tidine | Histamine H2-receptor antagonists, cimetidine type | H2 blocker | cimetidine, famotidine | One letter away from -tadine. | WHO stem book · MedlinePlus: famotidine |
| 55 | -setron | Serotonin 5-HT3 receptor antagonists | 5-HT3 antagonist | ondansetron, granisetron | Not the same as -triptan. | WHO stem book · USAN stem list (earlier copy) |
#53 · Stomach and gut
-prazole
- Official meaning
- Antiulcer agents of the benzimidazole type (the AMA says agents for ulcer and/or heartburn)
- Call it
- PPI (proton pump inhibitor)
- Examples
- omeprazole (Prilosec), lansoprazole (Prevacid)
- Watch out
- Aripiprazole looks similar but is an antipsychotic (see traps).
- Sources
- WHO stem book · AMA naming guidelines · MedlinePlus: omeprazole
#54 · Stomach and gut
-tidine
- Official meaning
- Histamine H2-receptor antagonists, cimetidine type
- Call it
- H2 blocker
- Examples
- cimetidine, famotidine
- Watch out
- One letter away from -tadine.
- Sources
- WHO stem book · MedlinePlus: famotidine
#55 · Stomach and gut
-setron
- Official meaning
- Serotonin 5-HT3 receptor antagonists
- Call it
- 5-HT3 antagonist
- Examples
- ondansetron, granisetron
- Watch out
- Not the same as -triptan.
- Sources
- WHO stem book · USAN stem list (earlier copy)
Lungs and allergy (5)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 56 | -tadine | Tricyclic histamine H1-receptor antagonists | H1 antihistamine | loratadine, desloratadine, olopatadine | One letter away from -tidine. | WHO stem book · USAN stem list (earlier copy) |
| 57 | -astine | Antihistaminics | H1 antihistamine | azelastine, clemastine | WHO stem book | |
| 58 | -lukast | Leukotriene receptor antagonists | Leukotriene receptor antagonist | montelukast (Singulair), zafirlukast | WHO stem book · AMA naming guidelines | |
| 59 | -terol | Bronchodilators, phenethylamine type | Bronchodilator | albuterol | WHO stem book · USAN stem list (earlier copy) | |
| 60 | -azoline | Antihistaminics or local vasoconstrictors, antazoline type | Local vasoconstrictor | oxymetazoline, naphazoline | WHO flags cefazolin as a name that ends this way without fitting the definition. | WHO stem book |
#56 · Lungs and allergy
-tadine
- Official meaning
- Tricyclic histamine H1-receptor antagonists
- Call it
- H1 antihistamine
- Examples
- loratadine, desloratadine, olopatadine
- Watch out
- One letter away from -tidine.
- Sources
- WHO stem book · USAN stem list (earlier copy)
#57 · Lungs and allergy
-astine
- Official meaning
- Antihistaminics
- Call it
- H1 antihistamine
- Examples
- azelastine, clemastine
- Watch out
- Sources
- WHO stem book
#58 · Lungs and allergy
-lukast
- Official meaning
- Leukotriene receptor antagonists
- Call it
- Leukotriene receptor antagonist
- Examples
- montelukast (Singulair), zafirlukast
- Watch out
- Sources
- WHO stem book · AMA naming guidelines
#59 · Lungs and allergy
-terol
- Official meaning
- Bronchodilators, phenethylamine type
- Call it
- Bronchodilator
- Examples
- albuterol
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#60 · Lungs and allergy
-azoline
- Official meaning
- Antihistaminics or local vasoconstrictors, antazoline type
- Call it
- Local vasoconstrictor
- Examples
- oxymetazoline, naphazoline
- Watch out
- WHO flags cefazolin as a name that ends this way without fitting the definition.
- Sources
- WHO stem book
Diabetes and hormones (12)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 61 | -formin | Antihyperglycemics, phenformin type | Biguanide | metformin | WHO stem book · MedlinePlus: metformin | |
| 62 | -gliptin | Dipeptidyl peptidase-4 (DPP-4) inhibitors | DPP-4 inhibitor | sitagliptin, saxagliptin | WHO stem book · MedlinePlus: sitagliptin · MedlinePlus: saxagliptin | |
| 63 | -gliflozin | Sodium-glucose co-transporter inhibitors | SGLT2 inhibitor | empagliflozin | WHO stem book · MedlinePlus: empagliflozin | |
| 64 | -glitazone | PPAR-gamma agonists (thiazolidinediones) | Thiazolidinedione | rosiglitazone | WHO stem book · USAN stem list (earlier copy) | |
| 65 | -glutide | Glucagon-like peptide (GLP) analogues | GLP analog (check which one) | liraglutide, semaglutide, teduglutide | Not always GLP-1: teduglutide is a GLP-2 analog. | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: semaglutide · MedlinePlus: teduglutide |
| 66 | pred / -methasone / -metasone | Prednisone and prednisolone derivatives | Corticosteroid | prednisone, prednisolone | "-sone" by itself is not an official stem. | WHO stem book |
| 67 | cort | Corticosteroids other than prednisolone derivatives | Corticosteroid | hydrocortisone | WHO stem book · USAN stem list (earlier copy) | |
| 68 | -onide | Topical steroids (acetal derivatives) | Topical corticosteroid | amcinonide | WHO stem book · USAN stem list (earlier copy) | |
| 69 | -olone | Steroids other than prednisolone derivatives | Steroid (check which kind) | nandrolone (filed with the androgens) | Not a corticosteroid guarantee. | WHO stem book |
| 70 | -ifene | Antiestrogens and estrogen receptor modulators (clomifene and tamoxifen type) | Estrogen receptor modulator | tamoxifen, raloxifene | WHO stem book · USAN stem list (earlier copy) | |
| 71 | -tocin | Oxytocin derivatives | Oxytocic | oxytocin | WHO stem book · USAN stem list (earlier copy) | |
| 72 | -pressin | Vasoconstrictors, vasopressin derivatives | Vasopressin analog | desmopressin | WHO stem book · USAN stem list (earlier copy) |
#61 · Diabetes and hormones
-formin
- Official meaning
- Antihyperglycemics, phenformin type
- Call it
- Biguanide
- Examples
- metformin
- Watch out
- Sources
- WHO stem book · MedlinePlus: metformin
#62 · Diabetes and hormones
-gliptin
- Official meaning
- Dipeptidyl peptidase-4 (DPP-4) inhibitors
- Call it
- DPP-4 inhibitor
- Examples
- sitagliptin, saxagliptin
- Watch out
- Sources
- WHO stem book · MedlinePlus: sitagliptin · MedlinePlus: saxagliptin
#63 · Diabetes and hormones
-gliflozin
- Official meaning
- Sodium-glucose co-transporter inhibitors
- Call it
- SGLT2 inhibitor
- Examples
- empagliflozin
- Watch out
- Sources
- WHO stem book · MedlinePlus: empagliflozin
#64 · Diabetes and hormones
-glitazone
- Official meaning
- PPAR-gamma agonists (thiazolidinediones)
- Call it
- Thiazolidinedione
- Examples
- rosiglitazone
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#65 · Diabetes and hormones
-glutide
- Official meaning
- Glucagon-like peptide (GLP) analogues
- Call it
- GLP analog (check which one)
- Examples
- liraglutide, semaglutide, teduglutide
- Watch out
- Not always GLP-1: teduglutide is a GLP-2 analog.
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: semaglutide · MedlinePlus: teduglutide
#66 · Diabetes and hormones
pred / -methasone / -metasone
- Official meaning
- Prednisone and prednisolone derivatives
- Call it
- Corticosteroid
- Examples
- prednisone, prednisolone
- Watch out
- "-sone" by itself is not an official stem.
- Sources
- WHO stem book
#67 · Diabetes and hormones
cort
- Official meaning
- Corticosteroids other than prednisolone derivatives
- Call it
- Corticosteroid
- Examples
- hydrocortisone
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#68 · Diabetes and hormones
-onide
- Official meaning
- Topical steroids (acetal derivatives)
- Call it
- Topical corticosteroid
- Examples
- amcinonide
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#69 · Diabetes and hormones
-olone
- Official meaning
- Steroids other than prednisolone derivatives
- Call it
- Steroid (check which kind)
- Examples
- nandrolone (filed with the androgens)
- Watch out
- Not a corticosteroid guarantee.
- Sources
- WHO stem book
#70 · Diabetes and hormones
-ifene
- Official meaning
- Antiestrogens and estrogen receptor modulators (clomifene and tamoxifen type)
- Call it
- Estrogen receptor modulator
- Examples
- tamoxifen, raloxifene
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#71 · Diabetes and hormones
-tocin
- Official meaning
- Oxytocin derivatives
- Call it
- Oxytocic
- Examples
- oxytocin
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#72 · Diabetes and hormones
-pressin
- Official meaning
- Vasoconstrictors, vasopressin derivatives
- Call it
- Vasopressin analog
- Examples
- desmopressin
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
Pain and inflammation (4)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 73 | -profen | Anti-inflammatory agents, ibuprofen type | NSAID (nonsteroidal anti-inflammatory drug) | ibuprofen, flurbiprofen | WHO stem book · USAN stem list (earlier copy) · MedlinePlus: ibuprofen | |
| 74 | -ac | Anti-inflammatory agents (the USAN list says acetic acid derivatives) | Anti-inflammatory | diclofenac, ketorolac, etodolac | WHO stem book | |
| 75 | -coxib | Selective cyclooxygenase inhibitors (the USAN list says COX-2) | COX-2 inhibitor | celecoxib | WHO stem book · USAN stem list (earlier copy) | |
| 76 | nal- (prefix) | Opioid receptor antagonists/agonists related to normorphine | Opioid antagonist family | nalmefene | A prefix, not a suffix. | WHO stem book · USAN stem list (earlier copy) |
#73 · Pain and inflammation
-profen
- Official meaning
- Anti-inflammatory agents, ibuprofen type
- Call it
- NSAID (nonsteroidal anti-inflammatory drug)
- Examples
- ibuprofen, flurbiprofen
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy) · MedlinePlus: ibuprofen
#74 · Pain and inflammation
-ac
- Official meaning
- Anti-inflammatory agents (the USAN list says acetic acid derivatives)
- Call it
- Anti-inflammatory
- Examples
- diclofenac, ketorolac, etodolac
- Watch out
- Sources
- WHO stem book
#75 · Pain and inflammation
-coxib
- Official meaning
- Selective cyclooxygenase inhibitors (the USAN list says COX-2)
- Call it
- COX-2 inhibitor
- Examples
- celecoxib
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#76 · Pain and inflammation
nal- (prefix)
- Official meaning
- Opioid receptor antagonists/agonists related to normorphine
- Call it
- Opioid antagonist family
- Examples
- nalmefene
- Watch out
- A prefix, not a suffix.
- Sources
- WHO stem book · USAN stem list (earlier copy)
Cancer, immune and other (11)
| # | Stem | Official meaning | Call it | Examples | Watch out | Sources |
|---|---|---|---|---|---|---|
| 77 | -mab | Legacy monoclonal-antibody stem | Monoclonal antibody (legacy naming) | abciximab | WHO discontinued -mab for newly named monoclonal antibodies in 2021 and replaced it with -tug, -bart, -ment and -mig. Older marketed names ending in -mab remain important to recognize. | WHO legacy stem book · WHO new monoclonal-antibody nomenclature · WHO 2026 stem-book addendum |
| 78 | -cept | Receptor molecules or membrane ligands | Receptor fusion protein | etanercept, abatacept | WHO stem book | |
| 79 | -tinib | Tyrosine kinase inhibitors | Kinase inhibitor | imatinib (Gleevec) | WHO stem book · AMA naming guidelines | |
| 80 | -platin | Platinum-derivative antineoplastics | Platinum chemotherapy | cisplatin | WHO stem book · USAN stem list (earlier copy) | |
| 81 | -taxel | Taxane antineoplastics | Taxane | paclitaxel | WHO stem book · USAN stem list (earlier copy) | |
| 82 | -rubicin | Daunorubicin-type antineoplastics | Daunorubicin-type antineoplastic | idarubicin | WHO stem book · USAN stem list (earlier copy) | |
| 83 | -trexate | Folic acid analogues | Antifolate | methotrexate | WHO stem book · USAN stem list (earlier copy) | |
| 84 | -rozole | Aromatase inhibitors (imidazole-triazole type) | Aromatase inhibitor | letrozole | WHO stem book · USAN stem list (earlier copy) | |
| 85 | -lutamide | Non-steroid antiandrogens | Antiandrogen | bicalutamide, flutamide | WHO stem book · USAN stem list (earlier copy) | |
| 86 | -imus / -rolimus | Immunosuppressants; -rolimus means rapamycin derivatives | Immunosuppressant | tacrolimus, sirolimus | WHO stem book · USAN stem list (earlier copy) | |
| 87 | -teplase | Tissue-type plasminogen activators (a subgroup of -ase, enzymes) | Thrombolytic enzyme | alteplase | -ase by itself just means "enzyme." | WHO stem book |
#77 · Cancer, immune and other
-mab
- Official meaning
- Legacy monoclonal-antibody stem
- Call it
- Monoclonal antibody (legacy naming)
- Examples
- abciximab
- Watch out
- WHO discontinued -mab for newly named monoclonal antibodies in 2021 and replaced it with -tug, -bart, -ment and -mig. Older marketed names ending in -mab remain important to recognize.
- Sources
- WHO legacy stem book · WHO new monoclonal-antibody nomenclature · WHO 2026 stem-book addendum
#78 · Cancer, immune and other
-cept
- Official meaning
- Receptor molecules or membrane ligands
- Call it
- Receptor fusion protein
- Examples
- etanercept, abatacept
- Watch out
- Sources
- WHO stem book
#79 · Cancer, immune and other
-tinib
- Official meaning
- Tyrosine kinase inhibitors
- Call it
- Kinase inhibitor
- Examples
- imatinib (Gleevec)
- Watch out
- Sources
- WHO stem book · AMA naming guidelines
#80 · Cancer, immune and other
-platin
- Official meaning
- Platinum-derivative antineoplastics
- Call it
- Platinum chemotherapy
- Examples
- cisplatin
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#81 · Cancer, immune and other
-taxel
- Official meaning
- Taxane antineoplastics
- Call it
- Taxane
- Examples
- paclitaxel
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#82 · Cancer, immune and other
-rubicin
- Official meaning
- Daunorubicin-type antineoplastics
- Call it
- Daunorubicin-type antineoplastic
- Examples
- idarubicin
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#83 · Cancer, immune and other
-trexate
- Official meaning
- Folic acid analogues
- Call it
- Antifolate
- Examples
- methotrexate
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#84 · Cancer, immune and other
-rozole
- Official meaning
- Aromatase inhibitors (imidazole-triazole type)
- Call it
- Aromatase inhibitor
- Examples
- letrozole
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#85 · Cancer, immune and other
-lutamide
- Official meaning
- Non-steroid antiandrogens
- Call it
- Antiandrogen
- Examples
- bicalutamide, flutamide
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#86 · Cancer, immune and other
-imus / -rolimus
- Official meaning
- Immunosuppressants; -rolimus means rapamycin derivatives
- Call it
- Immunosuppressant
- Examples
- tacrolimus, sirolimus
- Watch out
- Sources
- WHO stem book · USAN stem list (earlier copy)
#87 · Cancer, immune and other
-teplase
- Official meaning
- Tissue-type plasminogen activators (a subgroup of -ase, enzymes)
- Call it
- Thrombolytic enzyme
- Examples
- alteplase
- Watch out
- -ase by itself just means "enzyme."
- Sources
- WHO stem book
Brand names appear in parentheses only where the AMA pairs them with the generic name. The list teaches drug families, not doses or uses.
14 endings that point you the wrong way
Stems are clues, not guarantees. These are the places where reading only the last few letters gets you the wrong answer.
T01 · "-statin" means a cholesterol drug, right? · Show answer and explanation
Not quite. The cholesterol stem is -vastatin (atorvastatin, rosuvastatin). Nystatin only looks similar; it is a polyene antifungal.
Sources: WHO stem book · AMA naming guidelines · MedlinePlus: nystatin
T02 · Is every -mycin a macrolide? · Show answer and explanation
No. -mycin marks antibiotics that come from Streptomyces, not one class. Azithromycin is a macrolide, clindamycin is a lincomycin (lincosamide) antibiotic, and vancomycin is a glycopeptide.
Sources: WHO stem book · MedlinePlus: azithromycin · MedlinePlus: clindamycin · MedlinePlus: vancomycin
T03 · Are -micin and -mycin the same stem? · Show answer and explanation
No. -micin is its own stem for aminoglycosides from Micromonospora, such as gentamicin.
Sources: WHO stem book · USAN stem list (earlier copy)
T04 · Is every -azole an antifungal? · Show answer and explanation
No. Read the whole ending: -conazole is the antifungal stem (fluconazole), -prazole is the ulcer and heartburn stem (omeprazole), and -nidazole is the antiprotozoal stem (metronidazole).
Sources: WHO stem book · MedlinePlus: omeprazole
T05 · Aripiprazole ends in "-prazole." Is it a PPI? · Show answer and explanation
No. It is an atypical antipsychotic. WHO lists a separate psychotropic stem, -piprazole, and warns that it conflicts with -prazole.
Sources: WHO stem book · MedlinePlus: aripiprazole
T06 · What separates -tidine from -tadine? · Show answer and explanation
One letter and a whole receptor. -tidine drugs are H2 blockers (famotidine). -tadine drugs are H1 antihistamines (loratadine).
Sources: WHO stem book · USAN stem list (earlier copy) · MedlinePlus: famotidine
T07 · Cefazolin ends like -azoline. Is it a vasoconstrictor? · Show answer and explanation
No. The cef- prefix makes it a cephalosporin. WHO lists cefazolin as a name that ends like -azoline without fitting that stem's meaning.
Sources: WHO stem book
T08 · Does -olone always mean corticosteroid? · Show answer and explanation
No. WHO defines -olone as steroids other than prednisolone derivatives. Nandrolone ends in -olone and is filed with the androgens.
Sources: WHO stem book
T09 · Is -sone an official stem? · Show answer and explanation
No. Prednisone and prednisolone use the pred stem, and -methasone/-metasone are filed under pred.
Sources: WHO stem book
T10 · Does every calcium channel blocker end in -dipine? · Show answer and explanation
No. Diltiazem (-tiazem) and verapamil (-pamil) have their own calcium channel blocker stems.
Sources: WHO stem book
T11 · Carvedilol doesn't end in -olol. Is it a beta blocker? · Show answer and explanation
Yes. MedlinePlus classes carvedilol as a beta-blocker, even though its ending matches WHO's -dilol vasodilator stem.
Sources: WHO stem book · MedlinePlus: carvedilol
T12 · Does every prazosin-type drug end in -azosin? · Show answer and explanation
No. WHO lists tamsulosin and alfuzosin as related drugs that do not carry the -azosin stem.
Sources: WHO stem book
T13 · Does -glutide always mean GLP-1? · Show answer and explanation
No. -glutide means glucagon-like peptide analogs in general. Teduglutide is a GLP-2 analog; semaglutide is classed by MedlinePlus as an incretin mimetic.
Sources: WHO stem book · MedlinePlus: teduglutide · MedlinePlus: semaglutide
T14 · If a drug has no familiar stem, can you rule a class out? · Show answer and explanation
No. Escitalopram is an SSRI with no SSRI stem, and WHO groups butalbital with the barbiturates even though it lacks "barb."
Sources: MedlinePlus: escitalopram · WHO stem book
The fastest fix for most of these is to read the whole ending out loud: fluconazole, omeprazole, metronidazole. The letters just before "-azole" decide the family.
Drug suffix flashcards (101 cards)
Cover the right-hand column, say the answer, then check. The deck has one card for each of the 87 stems plus the 14 trap cards.
Card 1 of 101 · Heart and blood
-pril
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FC-001 · -pril · Reveal
ACE inhibitor. Official meaning: Angiotensin-converting enzyme inhibitors. Examples: enalapril, lisinopril. Watch out: -prilat is the same family (enalaprilat).
FC-002 · -sartan · Reveal
ARB (angiotensin II receptor blocker). Official meaning: Angiotensin II receptor antagonists. Examples: losartan, valsartan (Diovan).
FC-003 · -olol · Reveal
Beta blocker. Official meaning: Beta-adrenoreceptor antagonists. Examples: atenolol, timolol, metoprolol. Watch out: Not every beta blocker ends in -olol. See -alol and the carvedilol trap.
FC-004 · -alol · Reveal
Alpha/beta blocker. Official meaning: Related to the -olols; the USAN list calls them combined alpha and beta blockers. Examples: labetalol.
FC-005 · -dipine · Reveal
Calcium channel blocker. Official meaning: Calcium channel blockers, nifedipine type. Examples: nifedipine, felodipine, amlodipine. Watch out: Not every calcium channel blocker ends in -dipine (see -tiazem and -pamil).
FC-006 · -tiazem · Reveal
Calcium channel blocker. Official meaning: Calcium channel blockers, diltiazem type. Examples: diltiazem.
FC-007 · -pamil · Reveal
Calcium channel blocker. Official meaning: Calcium channel blockers, verapamil type. Examples: verapamil.
FC-008 · -vastatin (taught as "-statin") · Reveal
Statin. Official meaning: HMG-CoA reductase inhibitors, a subgroup of the broader -stat (enzyme inhibitor) stem. Examples: atorvastatin (Lipitor), rosuvastatin (Crestor), lovastatin, pravastatin. Watch out: Nystatin is not a statin. It is a polyene antifungal.
FC-009 · -semide · Reveal
Diuretic. Official meaning: Diuretics, furosemide type. Examples: furosemide. Watch out: Bumetanide uses a different stem (-etanide).
FC-010 · -etanide · Reveal
Diuretic. Official meaning: Diuretics, piretanide type. Examples: bumetanide.
FC-011 · -thiazide (WHO spelling: -tizide) · Reveal
Thiazide diuretic. Official meaning: Diuretics, chlorothiazide type. Examples: chlorothiazide.
FC-012 · -azosin · Reveal
Prazosin-type antihypertensive. Official meaning: Antihypertensives, prazosin type. Examples: doxazosin, prazosin, terazosin. Watch out: WHO lists tamsulosin and alfuzosin as related drugs that do not carry this stem.
FC-013 · -parin / -parinux · Reveal
Heparin-type anticoagulant. Official meaning: Heparin derivatives, including low-molecular-weight heparins; -parinux means synthetic heparinoids. Examples: heparin, dalteparin, tinzaparin; fondaparinux.
FC-014 · -xaban · Reveal
Factor Xa inhibitor. Official meaning: Blood coagulation factor Xa inhibitors. Examples: apixaban.
FC-015 · -grel · Reveal
Antiplatelet. Official meaning: Platelet aggregation inhibitors. Examples: clopidogrel (Plavix).
FC-016 · -afil · Reveal
PDE-5 inhibitor. Official meaning: PDE5 inhibitors with a vasodilator action. Examples: sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra).
FC-017 · -arone · Reveal
Antiarrhythmic. Official meaning: The USAN list defines it as antiarrhythmics. Examples: amiodarone, dronedarone. Watch out: WHO's listing also shows -arone on some drugs that are not antiarrhythmics, such as benzbromarone.
FC-018 · -cillin · Reveal
Penicillin. Official meaning: Penicillins (6-aminopenicillanic acid derivatives). Examples: amoxicillin, ampicillin, dicloxacillin, piperacillin.
FC-019 · cef- (prefix) · Reveal
Cephalosporin. Official meaning: Cephalosporins. Examples: cefazolin, cefdinir, ceftriaxone, cefuroxime. Watch out: Cefazolin ends like -azoline, but the cef- prefix decides the family.
FC-020 · -bactam · Reveal
Beta-lactamase inhibitor. Official meaning: Beta-lactamase inhibitors. Examples: sulbactam, tazobactam. Watch out: Clavulanic acid is in the same group without the stem.
FC-021 · -cycline · Reveal
Tetracycline. Official meaning: Tetracycline derivatives (protein-synthesis inhibitors). Examples: minocycline.
FC-022 · -oxacin (often taught as "-floxacin") · Reveal
Fluoroquinolone. Official meaning: Quinolone antibacterials (nalidixic acid derivatives). Examples: ciprofloxacin.
FC-023 · -mycin · Reveal
Check the drug. Official meaning: Antibiotics produced by Streptomyces strains. This names a source, not one drug class.. Examples: lincomycin; azithromycin (macrolide); clindamycin (lincomycin antibiotic); vancomycin (glycopeptide). Watch out: The biggest trap on this list.
FC-024 · -micin · Reveal
Aminoglycoside. Official meaning: Aminoglycosides obtained from Micromonospora. Examples: gentamicin. Watch out: -micin and -mycin are different stems.
FC-025 · -conazole · Reveal
Azole antifungal. Official meaning: Systemic antifungals, miconazole type. Examples: fluconazole, ketoconazole, itraconazole, voriconazole, miconazole. Watch out: Only -conazole means this. Not every -azole is an antifungal.
FC-026 · -nidazole · Reveal
Antiprotozoal (metronidazole type). Official meaning: Antiprotozoals, metronidazole type. Examples: metronidazole, tinidazole. Watch out: Not an antifungal.
FC-027 · sulfa- (prefix) · Reveal
Sulfonamide. Official meaning: Sulfonamide anti-infectives. Examples: sulfasalazine.
FC-028 · -zolid · Reveal
Oxazolidinone. Official meaning: Oxazolidinone antibacterials. Examples: linezolid.
FC-029 · -ciclovir / -cyclovir · Reveal
Antiviral (acyclovir type). Official meaning: Antivirals related in structure to acyclovir. Examples: acyclovir, ganciclovir, valacyclovir (Valtrex).
FC-030 · -amivir · Reveal
Neuraminidase inhibitor. Official meaning: Neuraminidase inhibitors. Examples: zanamivir.
FC-031 · -navir · Reveal
HIV protease inhibitor. Official meaning: HIV protease inhibitors. Examples: ritonavir, indinavir.
FC-032 · -tegravir · Reveal
Integrase inhibitor. Official meaning: HIV integrase inhibitors. Examples: elvitegravir.
FC-033 · -vudine · Reveal
Nucleoside antiviral. Official meaning: Uridine-type antivirals and antineoplastics (zidovudine group). Examples: lamivudine, stavudine.
FC-034 · -citabine · Reveal
Nucleoside analog. Official meaning: Nucleoside antivirals or antineoplastics. Examples: emtricitabine, gemcitabine. Watch out: Same ending, two very different uses.
FC-035 · -azepam · Reveal
Benzodiazepine. Official meaning: Diazepam derivatives. Examples: diazepam, lorazepam, clonazepam, temazepam.
FC-036 · -azolam · Reveal
Benzodiazepine. Official meaning: Filed by WHO with -azepam (diazepam derivatives). Examples: alprazolam, midazolam, triazolam. Watch out: Two endings, one family.
FC-037 · -pidem · Reveal
Sedative-hypnotic. Official meaning: Hypnotics and sedatives, zolpidem type. Examples: zolpidem. Watch out: Not a benzodiazepine stem.
FC-038 · -plon · Reveal
Sedative-hypnotic. Official meaning: Imidazopyrimidine or pyrazolopyrimidine anxiolytics, sedatives and hypnotics. Examples: zaleplon.
FC-039 · -clone · Reveal
Sedative-hypnotic. Official meaning: Hypnotic tranquilizers (zopiclone type). Examples: eszopiclone.
FC-040 · barb (-barbital) · Reveal
Barbiturate. Official meaning: Barbituric acid derivatives. Examples: phenobarbital, pentobarbital, secobarbital. Watch out: WHO lists butalbital in the same group without the stem.
FC-041 · -oxetine · Reveal
Antidepressant (fluoxetine family). Official meaning: Serotonin and/or norepinephrine reuptake inhibitors related to fluoxetine. Examples: fluoxetine, duloxetine (Cymbalta). Watch out: Covers more than one reuptake mechanism.
FC-042 · -traline · Reveal
SSRI (selective serotonin reuptake inhibitor). Official meaning: Serotonin reuptake inhibitors. Examples: sertraline. Watch out: Escitalopram is an SSRI with neither -traline nor -oxetine.
FC-043 · -faxine · Reveal
Antidepressant. Official meaning: The USAN Council defines it as antianxiety and antidepressant reuptake inhibitors. Examples: venlafaxine (Effexor XR). Watch out: A U.S. (USAN) stem; it is not in WHO's 2018 list.
FC-044 · -triptyline · Reveal
Tricyclic antidepressant. Official meaning: Antidepressants, dibenzocycloheptane type (WHO files it with the tricyclics). Examples: amitriptyline.
FC-045 · -pramine · Reveal
Tricyclic antidepressant. Official meaning: Imipramine group (WHO files it with the tricyclics). Examples: imipramine.
FC-046 · -peridone · Reveal
Antipsychotic. Official meaning: Antipsychotics, risperidone type. Examples: risperidone, iloperidone.
FC-047 · -peridol · Reveal
Antipsychotic. Official meaning: Antipsychotics, haloperidol type. Examples: haloperidol.
FC-048 · -spirone · Reveal
Anxiolytic. Official meaning: Anxiolytics, buspirone type. Examples: buspirone.
FC-049 · -triptan · Reveal
Triptan. Official meaning: Serotonin 5-HT1 receptor agonists, sumatriptan type (the USAN list says antimigraine agents). Examples: sumatriptan, naratriptan. Watch out: Not the same as -setron.
FC-050 · -caine · Reveal
Local anesthetic. Official meaning: Local anesthetics. Examples: lidocaine, benzocaine, bupivacaine, tetracaine. Watch out: "-cain-" inside a name (procainamide, flecainide) marks class I antiarrhythmics.
FC-051 · -dopa · Reveal
Dopaminergic (antiparkinson). Official meaning: Dopamine receptor agonists and dopamine derivatives used for parkinsonism. Examples: levodopa.
FC-052 · -pezil · Reveal
Cholinesterase inhibitor. Official meaning: The USAN list defines it as acetylcholinesterase inhibitors used in Alzheimer's disease. Examples: donepezil. Watch out: A U.S. (USAN) stem; it is not in WHO's 2018 list.
FC-053 · -prazole · Reveal
PPI (proton pump inhibitor). Official meaning: Antiulcer agents of the benzimidazole type (the AMA says agents for ulcer and/or heartburn). Examples: omeprazole (Prilosec), lansoprazole (Prevacid). Watch out: Aripiprazole looks similar but is an antipsychotic (see traps).
FC-054 · -tidine · Reveal
H2 blocker. Official meaning: Histamine H2-receptor antagonists, cimetidine type. Examples: cimetidine, famotidine. Watch out: One letter away from -tadine.
FC-055 · -setron · Reveal
5-HT3 antagonist. Official meaning: Serotonin 5-HT3 receptor antagonists. Examples: ondansetron, granisetron. Watch out: Not the same as -triptan.
FC-056 · -tadine · Reveal
H1 antihistamine. Official meaning: Tricyclic histamine H1-receptor antagonists. Examples: loratadine, desloratadine, olopatadine. Watch out: One letter away from -tidine.
FC-057 · -astine · Reveal
H1 antihistamine. Official meaning: Antihistaminics. Examples: azelastine, clemastine.
FC-058 · -lukast · Reveal
Leukotriene receptor antagonist. Official meaning: Leukotriene receptor antagonists. Examples: montelukast (Singulair), zafirlukast.
FC-059 · -terol · Reveal
Bronchodilator. Official meaning: Bronchodilators, phenethylamine type. Examples: albuterol.
FC-060 · -azoline · Reveal
Local vasoconstrictor. Official meaning: Antihistaminics or local vasoconstrictors, antazoline type. Examples: oxymetazoline, naphazoline. Watch out: WHO flags cefazolin as a name that ends this way without fitting the definition.
FC-061 · -formin · Reveal
Biguanide. Official meaning: Antihyperglycemics, phenformin type. Examples: metformin.
FC-062 · -gliptin · Reveal
DPP-4 inhibitor. Official meaning: Dipeptidyl peptidase-4 (DPP-4) inhibitors. Examples: sitagliptin, saxagliptin.
FC-063 · -gliflozin · Reveal
SGLT2 inhibitor. Official meaning: Sodium-glucose co-transporter inhibitors. Examples: empagliflozin.
FC-064 · -glitazone · Reveal
Thiazolidinedione. Official meaning: PPAR-gamma agonists (thiazolidinediones). Examples: rosiglitazone.
FC-065 · -glutide · Reveal
GLP analog (check which one). Official meaning: Glucagon-like peptide (GLP) analogues. Examples: liraglutide, semaglutide, teduglutide. Watch out: Not always GLP-1: teduglutide is a GLP-2 analog.
FC-066 · pred / -methasone / -metasone · Reveal
Corticosteroid. Official meaning: Prednisone and prednisolone derivatives. Examples: prednisone, prednisolone. Watch out: "-sone" by itself is not an official stem.
FC-067 · cort · Reveal
Corticosteroid. Official meaning: Corticosteroids other than prednisolone derivatives. Examples: hydrocortisone.
FC-068 · -onide · Reveal
Topical corticosteroid. Official meaning: Topical steroids (acetal derivatives). Examples: amcinonide.
FC-069 · -olone · Reveal
Steroid (check which kind). Official meaning: Steroids other than prednisolone derivatives. Examples: nandrolone (filed with the androgens). Watch out: Not a corticosteroid guarantee.
FC-070 · -ifene · Reveal
Estrogen receptor modulator. Official meaning: Antiestrogens and estrogen receptor modulators (clomifene and tamoxifen type). Examples: tamoxifen, raloxifene.
FC-071 · -tocin · Reveal
Oxytocic. Official meaning: Oxytocin derivatives. Examples: oxytocin.
FC-072 · -pressin · Reveal
Vasopressin analog. Official meaning: Vasoconstrictors, vasopressin derivatives. Examples: desmopressin.
FC-073 · -profen · Reveal
NSAID (nonsteroidal anti-inflammatory drug). Official meaning: Anti-inflammatory agents, ibuprofen type. Examples: ibuprofen, flurbiprofen.
FC-074 · -ac · Reveal
Anti-inflammatory. Official meaning: Anti-inflammatory agents (the USAN list says acetic acid derivatives). Examples: diclofenac, ketorolac, etodolac.
FC-075 · -coxib · Reveal
COX-2 inhibitor. Official meaning: Selective cyclooxygenase inhibitors (the USAN list says COX-2). Examples: celecoxib.
FC-076 · nal- (prefix) · Reveal
Opioid antagonist family. Official meaning: Opioid receptor antagonists/agonists related to normorphine. Examples: nalmefene. Watch out: A prefix, not a suffix.
FC-077 · -mab · Reveal
Legacy monoclonal-antibody stem. Example: abciximab. WHO discontinued -mab for newly named antibodies in 2021; newer names use -tug, -bart, -ment or -mig.
FC-078 · -cept · Reveal
Receptor fusion protein. Official meaning: Receptor molecules or membrane ligands. Examples: etanercept, abatacept.
FC-079 · -tinib · Reveal
Kinase inhibitor. Official meaning: Tyrosine kinase inhibitors. Examples: imatinib (Gleevec).
FC-080 · -platin · Reveal
Platinum chemotherapy. Official meaning: Platinum-derivative antineoplastics. Examples: cisplatin.
FC-081 · -taxel · Reveal
Taxane. Official meaning: Taxane antineoplastics. Examples: paclitaxel.
FC-082 · -rubicin · Reveal
Daunorubicin-type antineoplastic. Official meaning: Daunorubicin-type antineoplastics. Examples: idarubicin.
FC-083 · -trexate · Reveal
Antifolate. Official meaning: Folic acid analogues. Examples: methotrexate.
FC-084 · -rozole · Reveal
Aromatase inhibitor. Official meaning: Aromatase inhibitors (imidazole-triazole type). Examples: letrozole.
FC-085 · -lutamide · Reveal
Antiandrogen. Official meaning: Non-steroid antiandrogens. Examples: bicalutamide, flutamide.
FC-086 · -imus / -rolimus · Reveal
Immunosuppressant. Official meaning: Immunosuppressants; -rolimus means rapamycin derivatives. Examples: tacrolimus, sirolimus.
FC-087 · -teplase · Reveal
Thrombolytic enzyme. Official meaning: Tissue-type plasminogen activators (a subgroup of -ase, enzymes). Examples: alteplase. Watch out: -ase by itself just means "enzyme."
FC-T01 · "-statin" means a cholesterol drug, right? · Reveal
Not quite. The cholesterol stem is -vastatin (atorvastatin, rosuvastatin). Nystatin only looks similar; it is a polyene antifungal.
FC-T02 · Is every -mycin a macrolide? · Reveal
No. -mycin marks antibiotics that come from Streptomyces, not one class. Azithromycin is a macrolide, clindamycin is a lincomycin (lincosamide) antibiotic, and vancomycin is a glycopeptide.
FC-T03 · Are -micin and -mycin the same stem? · Reveal
No. -micin is its own stem for aminoglycosides from Micromonospora, such as gentamicin.
FC-T04 · Is every -azole an antifungal? · Reveal
No. Read the whole ending: -conazole is the antifungal stem (fluconazole), -prazole is the ulcer and heartburn stem (omeprazole), and -nidazole is the antiprotozoal stem (metronidazole).
FC-T05 · Aripiprazole ends in "-prazole." Is it a PPI? · Reveal
No. It is an atypical antipsychotic. WHO lists a separate psychotropic stem, -piprazole, and warns that it conflicts with -prazole.
FC-T06 · What separates -tidine from -tadine? · Reveal
One letter and a whole receptor. -tidine drugs are H2 blockers (famotidine). -tadine drugs are H1 antihistamines (loratadine).
FC-T07 · Cefazolin ends like -azoline. Is it a vasoconstrictor? · Reveal
No. The cef- prefix makes it a cephalosporin. WHO lists cefazolin as a name that ends like -azoline without fitting that stem's meaning.
FC-T08 · Does -olone always mean corticosteroid? · Reveal
No. WHO defines -olone as steroids other than prednisolone derivatives. Nandrolone ends in -olone and is filed with the androgens.
FC-T09 · Is -sone an official stem? · Reveal
No. Prednisone and prednisolone use the pred stem, and -methasone/-metasone are filed under pred.
FC-T10 · Does every calcium channel blocker end in -dipine? · Reveal
No. Diltiazem (-tiazem) and verapamil (-pamil) have their own calcium channel blocker stems.
FC-T11 · Carvedilol doesn't end in -olol. Is it a beta blocker? · Reveal
Yes. MedlinePlus classes carvedilol as a beta-blocker, even though its ending matches WHO's -dilol vasodilator stem.
FC-T12 · Does every prazosin-type drug end in -azosin? · Reveal
No. WHO lists tamsulosin and alfuzosin as related drugs that do not carry the -azosin stem.
FC-T13 · Does -glutide always mean GLP-1? · Reveal
No. -glutide means glucagon-like peptide analogs in general. Teduglutide is a GLP-2 analog; semaglutide is classed by MedlinePlus as an incretin mimetic.
FC-T14 · If a drug has no familiar stem, can you rule a class out? · Reveal
No. Escitalopram is an SSRI with no SSRI stem, and WHO groups butalbital with the barbiturates even though it lacks "barb."
PTCB drug suffix practice quiz (30 questions)
Original practice questions written by Castleport, not official PTCE items. Your score here is feedback on these 30 questions only, not a PTCE score or a prediction of passing.
Question 1 of 30 · ACE inhibitors
A prescription is written for enalapril. What class does its stem indicate?
0 correct of 0 answered (30 total)
Question 1: A prescription is written for enalapril. What class does its stem indicate? · Show answer and explanation
Answer: A. ACE inhibitor. -pril marks angiotensin-converting enzyme (ACE) inhibitors. ARBs end in -sartan, beta blockers in -olol, and nifedipine-type calcium channel blockers in -dipine.
Sources: WHO stem book · USAN stem list (earlier copy)
Question 2: Valsartan (Diovan) belongs to which group? · Show answer and explanation
Answer: C. Angiotensin II receptor antagonists. -sartan is the angiotensin II receptor antagonist stem. ACE inhibitors end in -pril, leukotriene receptor antagonists in -lukast, and PDE-5 inhibitors in -afil.
Sources: WHO stem book · AMA naming guidelines
Question 3: Which drug's stem identifies it as a beta blocker? · Show answer and explanation
Answer: D. metoprolol. -olol is the beta blocker stem. Montelukast (-lukast), metformin (-formin) and amlodipine (-dipine) belong to other families.
Sources: WHO stem book · MedlinePlus: metoprolol
Question 4: Labetalol ends in -alol, not -olol. What does the WHO stem list say about -alol? · Show answer and explanation
Answer: B. It is related to the -olol beta blockers. WHO files -alol as related to the -olols, and the USAN list describes it as combined alpha and beta blockers. Local anesthetics end in -caine, and -arone is the antiarrhythmic stem.
Sources: WHO stem book · USAN stem list (earlier copy)
Question 5: Which of these is NOT an HMG-CoA reductase inhibitor (statin)? · Show answer and explanation
Answer: D. nystatin. The cholesterol stem is -vastatin, which atorvastatin, rosuvastatin and pravastatin all carry. Nystatin only looks similar; MedlinePlus classes it as a polyene antifungal.
Sources: WHO stem book · AMA naming guidelines · USAN stem list (earlier copy) · MedlinePlus: nystatin
Question 6: Diltiazem and verapamil don't end in -dipine. What class are they? · Show answer and explanation
Answer: B. Calcium channel blockers. WHO defines three separate calcium channel blocker stems: -dipine (nifedipine type), -tiazem (diltiazem type) and -pamil (verapamil type). So -dipine is a reliable clue, but not the only one. ACE inhibitors use -pril, beta blockers -olol, and the diuretics on this list use -semide, -etanide or -thiazide.
Sources: WHO stem book
Question 7: Which pair are both filed with the diazepam (benzodiazepine) group? · Show answer and explanation
Answer: A. lorazepam and alprazolam. Lorazepam carries -azepam, and WHO files alprazolam's -azolam ending with the same group. Losartan is an ARB and albuterol a bronchodilator. Zolpidem (-pidem) and zaleplon (-plon) are sedative-hypnotics with their own stems.
Sources: WHO stem book
Question 8: A patient profile lists famotidine. What does its stem indicate? · Show answer and explanation
Answer: C. H2-receptor antagonist. -tidine is the H2-receptor antagonist stem, and MedlinePlus calls famotidine an H2 blocker. H1 antihistamines use -tadine, proton pump inhibitors use -prazole, and 5-HT3 antagonists use -setron.
Sources: WHO stem book · MedlinePlus: famotidine
Question 9: Which drug's stem marks an H1 antihistamine? · Show answer and explanation
Answer: B. desloratadine. -tadine marks tricyclic H1 antagonists. Cimetidine and famotidine end in -tidine (H2 blockers), and ondansetron ends in -setron (5-HT3 antagonist).
Sources: WHO stem book · USAN stem list (earlier copy)
Question 10: Which "-azole" drug is a systemic antifungal? · Show answer and explanation
Answer: D. fluconazole. Only -conazole is the systemic antifungal stem. Omeprazole and lansoprazole end in -prazole (ulcer and heartburn agents), and metronidazole ends in -nidazole (antiprotozoal).
Sources: WHO stem book · AMA naming guidelines
Question 11: Metronidazole's ending, -nidazole, indicates: · Show answer and explanation
Answer: C. An antiprotozoal of the metronidazole type. WHO defines -nidazole as antiprotozoals, metronidazole derivatives. The other choices describe -conazole, -prazole and the aripiprazole family.
Sources: WHO stem book
Question 12: Azithromycin and vancomycin both end in -mycin. Are they in the same drug class? · Show answer and explanation
Answer: A. No: azithromycin is a macrolide; vancomycin is a glycopeptide. WHO defines -mycin by where the antibiotic comes from (Streptomyces), not by class. MedlinePlus classes azithromycin as a macrolide and vancomycin as a glycopeptide; clindamycin, another -mycin, is a lincomycin antibiotic. Aminoglycosides use -micin and penicillins use -cillin.
Sources: WHO stem book · MedlinePlus: azithromycin · MedlinePlus: vancomycin · MedlinePlus: clindamycin
Question 13: Gentamicin's -micin ending indicates: · Show answer and explanation
Answer: D. Aminoglycoside. -micin is the stem for aminoglycosides from Micromonospora. Tetracyclines use -cycline, cephalosporins use cef-, and fluoroquinolones use -oxacin.
Sources: WHO stem book · USAN stem list (earlier copy)
Question 14: Cefazolin ends in letters that look like -azoline. What is it? · Show answer and explanation
Answer: B. A cephalosporin. The cef- prefix defines it. WHO's own listing flags cefazolin as a name that ends like -azoline without fitting that stem's meaning.
Sources: WHO stem book
Question 15: Aripiprazole ends in the letters "-prazole." What is its class? · Show answer and explanation
Answer: C. Atypical antipsychotic. MedlinePlus classes aripiprazole as an atypical antipsychotic. WHO lists it under a separate stem, -piprazole, and notes that this stem conflicts with -prazole. That is why you read the whole name.
Sources: WHO stem book · MedlinePlus: aripiprazole
Question 16: Teduglutide ends in -glutide, just like semaglutide. How does MedlinePlus classify teduglutide? · Show answer and explanation
Answer: A. GLP-2 analog. WHO defines -glutide as glucagon-like peptide (GLP) analogs without naming a subtype, and MedlinePlus classes teduglutide as a GLP-2 analog. So -glutide doesn't always mean GLP-1. DPP-4 inhibitors use -gliptin, SGLT2 inhibitors -gliflozin, and biguanides -formin.
Sources: WHO stem book · MedlinePlus: teduglutide · MedlinePlus: semaglutide
Question 17: Which of these ends in -olone but is filed by WHO with the androgens rather than as a corticosteroid? · Show answer and explanation
Answer: C. nandrolone. WHO defines -olone broadly (steroids other than prednisolone derivatives) and lists nandrolone with the androgens. Prednisolone uses pred, hydrocortisone uses cort, and amcinonide uses -onide.
Sources: WHO stem book · USAN stem list (earlier copy)
Question 18: Ciprofloxacin belongs to which group? · Show answer and explanation
Answer: D. Fluoroquinolones. -oxacin is the quinolone antibacterial stem, and MedlinePlus classes ciprofloxacin as a fluoroquinolone. Aminoglycosides use -micin, tetracyclines use -cycline, and macrolides have no single stem on this list.
Sources: WHO stem book · MedlinePlus: ciprofloxacin
Question 19: Carvedilol does not end in -olol. How does MedlinePlus classify it? · Show answer and explanation
Answer: B. Beta blocker. MedlinePlus classes carvedilol as a beta-blocker. Its ending matches WHO's -dilol vasodilator stem, which is exactly why a missing -olol doesn't rule the class out.
Sources: MedlinePlus: carvedilol · WHO stem book
Question 20: Zanamivir's -amivir ending marks: · Show answer and explanation
Answer: A. Neuraminidase inhibitors. -amivir is the neuraminidase inhibitor subgroup of the -vir stem. HIV protease inhibitors use -navir, integrase inhibitors use -tegravir, and acyclovir-type antivirals use -ciclovir/-cyclovir.
Sources: WHO stem book · USAN stem list (earlier copy)
Question 21: Valacyclovir (Valtrex) carries which stem subgroup, and what does it mean? · Show answer and explanation
Answer: C. -cyclovir: antiviral related to acyclovir. The AMA uses valacyclovir as its example of the -cyclovir subgroup, meaning a structure related to acyclovir. The other options are real stems, but valacyclovir doesn't carry them.
Sources: AMA naming guidelines
Question 22: Apixaban's stem marks: · Show answer and explanation
Answer: B. Factor Xa inhibitors. -xaban means factor Xa inhibitors, and MedlinePlus classes apixaban that way. Heparins use -parin, platelet aggregation inhibitors use -grel, and WHO's thrombin-inhibitor stem is -gatran.
Sources: WHO stem book · MedlinePlus: apixaban
Question 23: Clopidogrel (Plavix) is in which group? · Show answer and explanation
Answer: D. Platelet aggregation inhibitors. -grel is the platelet aggregation inhibitor stem; MedlinePlus calls clopidogrel an antiplatelet medication. Factor Xa inhibitors use -xaban, beta blockers -olol, heparins -parin.
Sources: WHO stem book · AMA naming guidelines · MedlinePlus: clopidogrel
Question 24: Sitagliptin's stem indicates: · Show answer and explanation
Answer: A. DPP-4 inhibitor. -gliptin means dipeptidyl peptidase-4 (DPP-4) inhibitors, which is how MedlinePlus classes sitagliptin. Biguanides use -formin, GLP analogs -glutide, thiazolidinediones -glitazone.
Sources: WHO stem book · MedlinePlus: sitagliptin
Question 25: Metformin belongs to which group? · Show answer and explanation
Answer: D. Biguanides. -formin is WHO's phenformin-type antihyperglycemic stem, and MedlinePlus classes metformin as a biguanide. The other groups use -gliptin, -gliflozin and -glutide.
Sources: WHO stem book · MedlinePlus: metformin
Question 26: Empagliflozin's stem marks: · Show answer and explanation
Answer: C. Sodium-glucose co-transporter (SGLT2) inhibitors. -gliflozin means sodium-glucose co-transporter inhibitors, and MedlinePlus classes empagliflozin as an SGLT2 inhibitor. The other classes use -gliptin, -glitazone and -formin.
Sources: WHO stem book · MedlinePlus: empagliflozin
Question 27: Escitalopram has no -traline or -oxetine ending. How does MedlinePlus classify it? · Show answer and explanation
Answer: B. SSRI. MedlinePlus classes escitalopram as an SSRI (selective serotonin reuptake inhibitor). A missing familiar stem doesn't rule a class out. Tricyclics use patterns such as -triptyline or -pramine, and benzodiazepines use -azepam or -azolam.
Sources: MedlinePlus: escitalopram · WHO stem book
Question 28: Sumatriptan and ondansetron both act on serotonin receptors. Which stem-and-action pairing is correct? · Show answer and explanation
Answer: C. -triptan: 5-HT1 agonist. WHO defines -triptan as 5-HT1 receptor agonists (sumatriptan) and -setron as 5-HT3 receptor antagonists (ondansetron). The first two options swap them, and H2 antagonists use -tidine.
Sources: WHO stem book · USAN stem list (earlier copy)
Question 29: Lidocaine's -caine ending marks: · Show answer and explanation
Answer: D. Local anesthetics. -caine is the local anesthetic stem. (WHO also has an internal "-cain-" stem for class I antiarrhythmics such as procainamide, but the -caine ending itself means local anesthetic.) The other options use -prazole, -pezil and -olol.
Sources: WHO stem book
Question 30: Why doesn't the brand name Lipitor reveal a drug class the way atorvastatin does? · Show answer and explanation
Answer: B. Naming rules keep USAN/INN stems out of trade names. The AMA's USAN principles and WHO resolution WHA46.19 both say stems should not be used in trade names. And the PTCE doesn't test only generic names: knowledge area 1.1 includes brand names.
Sources: AMA naming guidelines · WHO stem book · PTCE Content Outline
Missed a few? Find the stem in the list above, read its "Watch out" note, and redo that question tomorrow instead of right away.
How to read a generic name in 10 seconds
A U.S. generic name (a USAN) is usually built from up to three parts, according to the AMA's naming guidelines:
- Prefix: means nothing. It only tells one drug apart from others in the same family.
- Infix (sometimes): a middle piece that groups closely related drugs.
- Stem: usually at the end, sometimes at the start (cef-). It places the drug in its family.
The AMA's own example: sildenafil, vardenafil and tadalafil all end in -afil, the PDE-5 inhibitor stem. The -den- infix shows that sildenafil and vardenafil have similar structures. Sil-, var- and tadal- are just prefixes.
A few prefixes and infixes do mean something. Es-, lev-/levo-, dex-/dextro-, ar- and rac- mark mirror-image (stereoisomer) or mixed forms of a drug that already has a name; the AMA gives levocarnitine, dexibuprofen and dextroamphetamine as examples. An -io- infix means high iodine content (amiodarone), and -fos- anywhere in a name means phosphorus.
Brand names skip all of this on purpose. Both the AMA's USAN principles and a World Health Assembly resolution (WHA46.19, described in the WHO stem book) say stems should not be used in trade names. "Lipitor" tells you nothing; "atorvastatin" tells you it's a statin.
Where suffixes fit on the 2026 PTCE
The current PTCE content outline, effective January 6, 2026, puts Medications at 35% of the exam. Its first knowledge area (1.1) is "generic names, brand names, and classifications of medications." Stems help with the classification part, and the trap list above supports knowledge area 3.1, look-alike/sound-alike medications.
Two limits worth knowing. The 35% covers the whole Medications domain, not suffixes alone, and PTCB doesn't say how many questions touch drug names. And the outline lists knowledge areas, not drugs or stems, so no suffix list (including this one) is the official boundary of what can be tested. Stems won't teach you brand names, which 1.1 also covers.
For the rest of the exam — format, weights, fees and retakes — see our PTCB exam prep guide.
A five-session study plan
This is a suggested schedule, not an official requirement. Each session uses the same routine: cover the "Call it" column, say the class for each stem, reverse it (read a class, name an example), then read the related traps.
| Session | Study | Then check yourself with |
|---|---|---|
| 1 | Heart and blood (stems 1–17) | Traps T01, T10, T11, T12 · flashcards FC-001 to FC-017 |
| 2 | Infections (stems 18–34) | Traps T02, T03, T04, T07 · flashcards FC-018 to FC-034 |
| 3 | Brain, stomach and lungs (stems 35–60) | Traps T05, T06, T14 · flashcards FC-035 to FC-060 |
| 4 | Diabetes, hormones, pain, cancer (stems 61–87) | Traps T08, T09, T13 · flashcards FC-061 to FC-087 |
| 5 | All 30 quiz questions | Re-study the stem behind every miss, then redo only those questions |
If you only have one sitting, do the 14 traps and the quiz. Those are where shortcuts break.
Quick answers
Is there an official PTCB list of drug suffixes?
No. The PTCE outline names knowledge areas, not drugs or stems. The stems themselves are set by the USAN Council in the U.S. and by the WHO internationally, which is why this page checks them there.
Are brand names on the PTCE?
Yes, knowledge area 1.1 includes brand names. Stems can't help with those, because naming rules keep stems out of brand names. Pair each generic you learn here with its brand separately.
Does this list work for the ExCPT?
The stems are the same for any U.S. generic name, but the ExCPT is a different exam with its own outline. See our ExCPT exam prep page for that exam.
Sources and how we checked
We checked the stem meanings used here against WHO stem-book material and the AMA's current USAN naming guidance, then checked the current WHO 2024 stem-book publication and its February 2026 cumulative addendum for changes relevant to this set. The main currentness correction is the antibody row: WHO discontinued -mab for newly named monoclonal antibodies and now uses -tug, -bart, -ment and -mig; older -mab drug names remain useful recognition examples. Some U.S.-only stem examples still rely on an earlier copy of the USAN stem list because the current AMA spreadsheet was not machine-readable in this audit; those rows are labeled as U.S. stems rather than presented as newly verified additions. Drug classes named on this page were checked against MedlinePlus (U.S. National Library of Medicine). Exam facts come from PTCB's current content outline. This was an editorial source check, not a professional pharmacist review.
- PTCB: PTCE Content Outline, effective January 6, 2026
- WHO: The use of stems in the selection of INN for pharmaceutical substances (2024) — current stem-book edition
- WHO: INN Stem Book Addendum 202602-2024 — cumulative new stems and definition changes since the 2024 edition
- WHO: New INN nomenclature scheme for monoclonal antibodies — discontinues -mab for newly named antibodies and defines -tug, -bart, -ment and -mig
- WHO: 2018 stem book — exact legacy definitions and stem listings used by the row-level citations
- AMA: United States Adopted Names naming guidelines
- AMA: USAN approved stems (current list)
- USAN stem list, earlier copy (examples only)
- MedlinePlus drug pages: amlodipine, apixaban, aripiprazole, azithromycin, carvedilol, ciprofloxacin, clindamycin, clopidogrel, empagliflozin, escitalopram, famotidine, ibuprofen, lisinopril, metformin, metoprolol, nystatin, omeprazole, saxagliptin, semaglutide, sitagliptin, teduglutide, vancomycin
Last verified: September 24, 2026 — the PTCE outline, the naming references and the drug classes cited on this page. Found an error? Tell us through our corrections process.
Castleport Test Prep is an independent exam-prep publisher and is not affiliated with, endorsed by, or approved by the Pharmacy Technician Certification Board (PTCB). Exam, credential and drug brand names are used only to identify their subjects; trademarks belong to their respective owners. The practice questions and flashcards on this page are original and unofficial. This page teaches drug-name patterns for exam study; it is not medical advice.