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International Nonproprietary Names (INNs) - Common Stems

List of Common Stems Used in the Selection of INNs.


Stem Definition & substem (if available)


-ac anti-inflammatory agents, ibufenac derivatives
-actide synthetic polypeptides with a corticotrophin-like action
-adol or -adol- analgesics
-adom analgesics, tifluadom derivatives
-afenone antiarrhythmics, propafenone derivatives
-aj- antiarrhythmics, ajmaline derivatives
-aldrate antacids, aluminium salts
-alox antacids, aluminium derivatives
-amivir see vir  
andr steroids, androgens
-anserin serotonin receptor antagonists (mostly 5-HT2)
-antel anthelminthics (underfined group)
-apine see -pine
-arabine arabinofuranosyl derivatives
-arit antiarthritic substances, acting like clobuzarit and lobenzarit (mechanism different from anti-inflammatory type substances, eg -fenamates or -profens)
-arol anticoagulants, dicoumarol derivatives
arte- antimalarial agents, artemisinin related compounds
-ase enzymes;
-dismase (superoxide dismutase activity),
-pase (lipase)
-teplase (tissue plasminogen activators),
      -uplase (urokinase-type-plasminogen activators)
-ast antiasthmatic, antiallergics, not acting primarily as antihistaminics;
       -lukast (leukotriene receptor antagonist);
       -trodast (thromboxane A2 receptor antagonists, antiasthmatics)                        
-astine antihistaminics
-azenil benzodiazepine receptor antagonists/agonists (benzodiazepine derivatives)
-azepam diazepam derivatives
-azepide cholecystokinin receptor antagonist
-azocine narcotic antagonists/agonists related to 6,7-benzomorphan
-azoline antihistaminics or local vasoconstrictors, antazoline derivatives
-azosin antihypertensive substances, prazosin derivatives


-bactam b-lactamase inhibitors
-bamate tranquillizers, propanediol and pentanediol derivatives
barb hypnotics, barbituric acid derivatives
-bendazole anthelminthics, tiabendazole derivatives
bol anabolic steroids
-bradine bradycardic agents
-buzone anti-inflammatory analgesics, phenylbutazone derivatives


-cain- Class 1 antiarrhythmics, procainamide and lidocaine derivatives (antifibrillants with local anaesthetic activity)
-caine local anaesthetics
calci Vitamin D analogues/derivatives
-carbef antibiotics, carbacepham derivatives
-carnil benzodiazepine receptor antagonists/agonists (carboline derivatives)
-cavir see vir
cef- antibiotics, cefalosporanic acid derivatives
cell- or cel- or -cell- cellulose derivatives
      cell-ate (cellulose ester derivatives);
      -cellose (cellulose ether derivatives)
-cic hepatoprotectice substances with a carboxylic acid group
-cidin naturally occurring antibiotics (undefined group)
-cillin antibiotics, 6-aminopenicillanic acid derivatives
-citabine nucleoside antiviral or antineoplastic agents, cytarabine or azarabine derivatives
-clone hypnotic tranquillizers
-cog blood coagulation factors;
      (-)eptacog (blood coagulation VII);
      (-)octocog (blood coagulation factor VIII);
      (-)nonacog (blood coagulation factor IX)
-conazole systemic antifungal agents, miconazole derivatives
cort corticosteroids, except prednisolone derivatives
-crinat diuretics, etacrynic acid derivatives
-crine acetylcholinesterase inhibitors, tacrine derivatives
-cromil antiallergics, cromoglicic acid derivatives
-curium see -ium
-cycline antibiotics, tetracycline derivatives


-dan cardiac stimulants, pimobendan derivatives
-dapsone Antimycobacterials, diaminodiphenylsulfone derivatives
-dermin see -ermin
-dil vasodilators
-dipine calcium channel blockers, nifedipine derivatives
-dismase see -ase
-dopa dopamine receptor agonists, dopamine derivatives, used as antiparkinsonism/prolactin inhibitors;
-dox antibacterials, quinoline dioxide derivatives
-dralazine antihypertensives, hydrazinephthalazine derivatives
-drine sympathomimetics;
      -frine: sympathomimetic, phenethyl derivatives
-dronic acid calcium metabolism regulator, pharmaceutical aid


-ectin antiparasitics, ivermectin derivatives
-entan endothelin receptor antagonists
-eptacog see –cog
erg ergot alkaloid derivatives
-eridine analgesics, pethidine derivatives
-ermin growth factors;
-dermin (epidermal growth factors);
-fermin (fibrinoblast growth factors);
-nermin (tumour necrosis factor);
-sermin (insulin-like growth factors)
estr estrogens
-etanide diuretics, piretanide derivatives
-exakin see -kin
-exine mucolytic, bromhexine derivatives


-fenamic acid anti-inflammatory, anthranilic acid derivatives
-fenamate (“-fenamic acid” derivatives)
-fenin diagnostic aids; (phenylcarbamoyl)methyl iminodiacetic acid derivatives
-fenine analgesics, glafenine derivatives - (subgroup of fenamic acid group)
-fentanil narcotic analgesics, fentanil derivatives
-fermin see –ermin
-fiban Fibrinogen receptor antagonists (glycoprotein lib/llla receptor antagonists
-fibrate clofibrate derivatives
-flapon 5-lipoxygenase-activating protein (FLAP) inhibitor
-flurane general inhalation anaesthetics, halogenated alkane derivatives
-formin antihyperglycaemics, phenformin derivatives
-fos (-vos) insecticides, anthelmintics,pesticides etc., phosphorous derivatives
-fos- or fos- various pharmacological categories belonging to -fos (other than above)
-fradil calcium channel blockers acting as vasodilators
-frine see -drine
-fungin antifungal antibiotics
-fylline N-methylated xanthine derivatives


gab gabamimetic agents
gado- diagnostic agents, gadolinium derivatives
-gatran thrombin inhibitor, antithrombotic agents
gest steroids, progestogens
-giline MAO-inhibitors type B
-gillin antibiotics produced by Aspergillus strains
gli antihyperglycaemics, sulfonamide derivatives
-golide dopamine receptor agonists, ergoline derivatives
-gramostim see -stim
-grastim see -stim
-grel- or -grel platelet aggregation inhibitors
guan- antihypertensives, guanidine derivatives


-icam anti-inflammatory, isoxicam derivatives
-ifene antiestrogens, clomifene and tamoxifen derivatives
-ilide Class III antiarrhythmics, sematilide derivatives
imex immunostimulants
-imod immunomodulators, both stimulant/suppressie and stimulant
-imus immunosuppressants (other than antineoplastics)
io- iodine-containing contrast media
-io- or iod- iodine containing compounds other than contrast media
-iptan serotonin (5HT1) receptor agonists, sumatriptan derivatives
-irudin hirudin derivatives
-isomide antiarrhythmics, disopyramide derivatives
-ium quarternary ammonium compounds
- curium (curare-like substances)
-izine diphenylmethyl piperazine derivatives
-rizine (antihistaminics/cerebral (or peripheral) vasodilators)


-kacin antibiotics, kanamycin and bekanamycin derivatives (obtained from Streptomyces kanamyceticus);
-kalant potassium channel blockers
-kalim potassium channel activators, antihypertensive
-kef- enkephalin agonists
-kin interleukin type substances;
-nakin (ll-1 derivatives)
-leukin (ll-2 derivatives)
-plestim (ll-3 derivatives)
-exakin (ll-6 derivatives)
-kinra interleukin receptor antagonists;
-nakinra (ll-1 receptor antagonists)
-kiren renin inhibitors


-leukin see -kin
-lipastat see -stat
-lukast see -ast


-mab monoclonal antibodies (for details please see page …..)
-mantadine adamantine derivatives;
-mantine, -mantone
-meline cholinergic agents, arecoline derivatives
-mer polymers
-mesine sigma receptor ligands
-mestane aromatase inhibitors
-metacin anti-inflammatory, indometacin derivatives
-micin antibiotics obtained from various Micromonospora
-monam monobactam antibiotics
-morelin see -relin
-mostim see -stim
-motine antivirals, quinoline derivatives
-moxin monoamine oxidase inhibitors, hydrazine derivatives ** not part of definition
-mustine antineoplastic, alkylating agents, (b-chloroethyl) amine derivatives
-mycin antibiotics, produced by Streptomyces strains


nab cannabinol derivatives
-nakin see -kin
-nakinra see -kinra
nal- narcotic antagonists/agonists related to normorphine
-nercept tumour necrosis factor antagonist
-nermin see -ermin
nic nicotinic acid or nicotinoyl alcohol derivatives
-nicate antihypercholesterolaemic and/or vasodilating nicotinic acid esters
-nidazole antiprotozoals, metronidazole derivatives
nifur- 5-nitrofuran derivatives
-nixin anti-inflammatory, anilinonicotinic acid derivatives
-nonacog see -cog


-octocog see -cog
-olol b-adrenoreceptor antagonists
-alol: aromatic ring –CH-CH2-NH-R related to -olols
-olone steroids other than prednisolone derivatives
-opamine dopaminergic agents dopamine derivatives used as cardiac stimulat/antihypertensives/diuretics
-onide steroids for topical use, acetal derivatives
-(o)nidine antihypertensives, clonidine derivatives
-orex anoretics
orphan narcotic antagonists/agonists, morphinan derivates;
-orphine, -orphinol, orphone
-oxacin antibacterials, nalidixic acid derivatives
-oxan(e) benzodioxane derivatives
-oxanide antiparasitics, salicylanides and analogues
-oxef antibiotics, oxacefalosporanic acid derivatives
-oxetine antidepressants, fluoxetine derivatives


-pafant platelet-activating factor antagonists
-pamide diuretics, sulfamoylbenzoic acid derivatives
-pamil coronary vasodilators, verapamil derivatives
-parcin glycopeptides antibiotics
-parin heparin derivatives including low molecular mass heparins
-penem analogues of penicillanic acid antibiotics modified in the five-membered ring
-peridol see –perone
-peridone see –perone
-perone tranquillizers, neuroleptics, 4’-fluoro-4-piperidinobutyrophenone derivatives;
- peridol (antipsychotics, haloperidol derivatives);
-peridone (antipsychotics, risperidone derivatives)
-pidem hypnotics/sedatives, zolpidem derivatives
-pin(e) tricyclic compounds
-apine (psychoactive);
-cilpine (antiepileptic);
-dipine (see –dipine)
-zepine (antidepressant/neuroleptic;
-oxepin, -oxopine, -sopine, -tepines
-piprazole psychotropics, phenylpiperazine derivatives
-pirox antimycotic pyridine derivatives
-planin antibacterials (Actinoplanes strains)
-platin antineoplastic agents, platinum derivatives
-plestim see –stim
-plon pyrazolo[-]pyrimidine derivatives, used as anxiolytics, sedatives, hypnotics
-poetin erythropoietin type blood factors
-porfin benzoporphyrin derivatives
-pramine substances of the imipramine group
-prazole antiulcer, benzimidazole derivatives
pred prednisone and prednisolone derivatives;
methazone or –metasone, -betasol
-pressin vasoconstrictors, vasopressin derivatives
-pride sulpiride derivatives
-pril(at) angiotensin-converting enzyme inhibitors
-prim antibacterials, trimethoprim derivatives
-profen anti-inflammatory agents, ibuprofen derivatives
prost prostaglandins;
-prostil (prostaglandins, anti-ulcer)
-prostil see -prost


-quinil benzodiazepine receptor partial agonists (quinoline derivatives)


-racetam amide type nootrope agents, piracetam derivatives
-relin prehormones or hormone-release stimulating peptides;
-morelin (growth hormone release-stimulating peptides);
-tirelin (thyrotropin releasing hormone analogues)
-relix hormone-release inhibiting peptides
-renone aldosterone antagonists, spironolactone derivates
-restat (or -restat-) see –stat
retin retinol derivatives
-ribine ribofuranil-derivatives of the pyrazofurin type
rifa- antibiotics, rifamycin derivatives
-rinone cardiac stimulants, amrinone derivatives
-rizine see –izine
-rozole aromatase inhibitors, imidozole-triazole derivatives
-rubicin antineoplastic antibiotics, daunorubicin derivatives


sal salicylic acid derivatives:
-sal-, salazo-, -salazine/-salazide, -salan
-sartan angiotensin II receptor antagonists, antihypertensive (non-peptidic)
-semide diuretics, furosemide derivatives
-sermin see –ermin
-serpine derivatives of Rauwolfia alkaloids
-setron serotonin receptor antagonists (5-HT3), not fitting into other established groups of serotonin receptor antagonists
som- growth hormone derivatives
-spirone anxiolytics, buspirone derivatives
-stan- or -ster- steroids, androgens
-stat (or -stat-) enzyme inhibitors:
-lipastat (pancreatic lipase inhibitors);
restat or -restat- (aldose-reducing inhibitors);
-vastatin (antilipidemic substances, HMG CoA reductase inhibitors
-steine mucolytics, other than bromhexine derivatives
-ster- androgens/anabolic steroids:
-testosterone, -sterone, -ster-, -gesterone, -sterone, sterol, ster,
-stim colony stimulating factors:
-grastim (granulocyte colony stimulatory factor (G-CSF) type) substances;
-gramostim (granulocyte macrophage colony stimulating factor (GM-CSF) type substances);
-mostim (macrophage stimulating factors (M-CSF) type substances);
-plestim (interleukin-3 analogues and derivatives)
sulfa- anti-infectives, sulfonamides
-sulfan antineoplastic, alkylating agents, methanesulfonates


-tecan antineoplastics, topoisomerase I inhibitors
-tepa antineoplastics, thiotepa derivatives
-teplase see -ase
-terol bronchodilators, phenethylamine derivatives
(previously -prenaline or -terenol)
-terone antiandrogens
-tiazem calcium channel blockers, diltiazem derivatives
-tide peptides and glycopeptides
(for special groups of peptides see -actide, -pressin, -relin, -tocin)
-tidine histamine H2-receptor antagonists, cimetidine derivatives
-tirelin see -relin
-tizide diuretics, chlorothiazide derivatives
-tocin oxytocin derivatives
-toin antiepileptics, hydantoin derivatives
-trexate folic acid analogues
-tricin antibiotics, polyene derivatives
-triptyline antidepressants, dibenzo[a,d]cycloheptane or cyclopheptene derivatives
-troban thromboxane A2-receptor antagonists; antithrombotic agents
-trodast see -ast
trop atropine derivatives


-uplase see -ase
-uracil uracil derivatives used as thyroid antagonists and as antineoplastics
-uridine uridine derivatives used as antiviral agents and as antineoplastics; also -udine­


-vastatin see -stat
-verine spasmolytics with a papaverine-like action
vin- or -vin- vinca alkaloids
vir antivirals (underfined group):
-amivir (neuraminidase inhibitors);
-cavir (carbocyclic nucleosides);
-virsen (antisense oligonucleotides)
-virsen see vir
-vudine antiviral; antineoplastics, zidovudine derivatives


-xanox antiallergic respiratory tract drugs, xanoxic acid derivatives


-zofone alozafone derivatives
-zepine see -pine

Return to International Nonproprietary Names.

Explanatory notes:

  • The hyphens indicate the position of the stem, prefix, infix or suffix, within the INN.  In the event that the hyphen is absent, the stem may be used in any position within the name.
  • The following common stems have been discontinued:
Stem Definition
mer- or -mer- mercury-containing drugs, antimicrobial or diuretic
(deleted from General Principles in List 28 prop. INN)
mito- antineoplastics, nucleotoxic agents
(deleted from General Principles in List 24 prop. INN)
-ol alcohols and phenols
(deleted from General Principles in 14th report)
-quine, quin quinoline derivatives
(deleted from General Principles in List 28 prop. INN)
-stigmine anticholinesterases
(deleted from General Principles in List 24 prop. INN)