In atorvastatin calcium, atorvastatin is the name WHO gave the medicine (the INN) and calcium says it is made as a calcium salt. In adalimumab-atto, adalimumab is the INN and -atto is a four-letter suffix the US FDA adds to biological products; its letters mean nothing. Type a name to split it.
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The name is split into the INN, any salt, ester or water words, and any FDA suffix, each linked to what it means. Nothing you type leaves your browser.
WHO gives an INN to the active part of a molecule only, usually the base, acid or alcohol. When a medicine is made as a salt or an ester, the second word names the other part, and WHO calls the two-word result a modified INN (INNM): mepyramine maleate is mepyramine joined with maleic acid. WHO's rule is that names for different salts or esters of the same substance differ only in that second word. For long chemical names WHO coins a short one: mesilate for methanesulfonate, besilate for benzenesulfonate, erbumine for 2-methylpropan-2-amine.
US spellings differ. WHO writes -silate where US names write -sylate: imatinib mesilate is imatinib mesylate on a US label, and WHO's embonate is the US pamoate. When the INN itself is an acid named with the word acid, WHO puts the metal first (sodium valproate, disodium pamidronate), while US labels put it last (valproate sodium, pamidronate disodium).
No word in the table starts with that. The decoder sets aside only these words; any other word is read as part of the name.
| Word | What it names | Also written | Example | Source |
|---|---|---|---|---|
| acetate salt or ester word | a salt or ester of acetic acid | — | glatiramer acetate | WHO INNM, section VI: desoxycortone acetate, zuclopenthixol acetate checked 2026-09-24 |
| acid part of the name itself | part of the INN when WHO named the substance as an acid; in its salts and esters the -ic acid becomes -ate | -ate valproic acid gives sodium valproate, clavulanic acid gives potassium clavulanate | valproic acid | WHO INNM, para. 10 checked 2026-09-24 |
| alfa part of the name itself | a Greek letter spelt in full, added as a second word to the INN of a glycosylated protein; letters go in Greek alphabetical order from alfa to tell glycosylation variants apart | alpha WHO writes alfa, and not alpha | epoetin alfa | WHO biologicals review, section 2.2 and Annex 4 checked 2026-09-24 |
| anhydrous water word | the solid carries no bound water | — | levopropoxyphene napsylate anhydrous | WHO INNM, section IV: water in a substance is named by a word after the INN checked 2026-09-24 |
| aspartate salt or ester word | a salt of aspartic acid | — | amphetamine aspartate | WHO INNM, para. 8: English INNM = INN of the base + name of the anion checked 2026-09-24 |
| axetil ester group | an ester with the group rac-1-(acetyloxy)ethyl, a short name WHO coined for it | — | cefuroxime axetil | WHO INNM, para. 17 (table) and para. 19: cefuroxim axetil checked 2026-09-24 |
| benzoate salt or ester word | a salt or ester of benzoic acid | — | rizatriptan benzoate | WHO INNM, para. 8 checked 2026-09-24 |
| besilate salt or ester word | a salt of benzenesulfonic acid; besilate is WHO's short name for benzenesulfonate | besylate US (USAN) spelling | amlodipine besilate | WHO radicals list, entry besilate (USAN: besylate); also INNM para. 7 checked 2026-09-24 |
| besylate salt or ester word | a salt of benzenesulfonic acid; the US spelling of WHO's besilate | besilate WHO (INN) spelling | amlodipine besylate | WHO radicals list, entry besilate (USAN: besylate) checked 2026-09-24 |
| beta part of the name itself | the second Greek letter, spelt in full as a second word of a glycosylated protein's INN; it marks the variant named after the alfa one | — | epoetin beta | WHO biologicals review, section 2.2 and Annex 4 checked 2026-09-24 |
| bisulfate salt or ester word | a salt of sulfuric acid in which one of its two acid hydrogens remains (hydrogen sulfate) | hydrogen sulfate the chemical name of the same anion | clopidogrel bisulfate | WHO INNM, para. 8: salts of inorganic acids follow inorganic nomenclature checked 2026-09-24 |
| bitartrate salt or ester word | a salt of tartaric acid in which one of its two acid hydrogens remains (hydrogen tartrate) | hydrogen tartrate the chemical name of the same anion | hydrocodone bitartrate | WHO INNM, para. 8 checked 2026-09-24 |
| bromide salt or ester word | the negative ion of the salt is bromide | — | aclidinium bromide | WHO INNM, para. 24: ipratropium bromide checked 2026-09-24 |
| butyrate salt or ester word | an ester or salt of butyric (butanoic) acid | — | hydrocortisone butyrate | WHO INNM, para. 21: the INN of the alcohol stays and the acid becomes -ate checked 2026-09-24 |
| calcium salt word | the calcium salt of a medicine that is itself the acid part | — | atorvastatin calcium | WHO INNM, paras. 12-13: acamprosate calcium, mupirocin calcium checked 2026-09-24 |
| carbonate salt or ester word | a salt of carbonic acid | — | sevelamer carbonate | WHO INNM, para. 8 checked 2026-09-24 |
| chloride salt or ester word | the negative ion of the salt is chloride (usual for quaternary ammonium compounds and metals, where a base gives hydrochloride) | — | trospium chloride | WHO INNM, para. 24: benzododecinium chloride, gantacurium chloride checked 2026-09-24 |
| cilexetil ester group | an ester with the group rac-1-{[(cyclohexyloxy)carbonyl]oxy}ethyl, a short name WHO coined for it | — | candesartan cilexetil | WHO INNM, para. 17 (table) and para. 19: sanfetrinem cilexetil checked 2026-09-24 |
| citrate salt or ester word | a salt of citric acid | — | sildenafil citrate | WHO INNM, para. 8 checked 2026-09-24 |
| dihydrate water word | two molecules of water are bound to each molecule of the substance | — | oxytetracycline dihydrate | WHO INNM, para. 15 checked 2026-09-24 |
| dihydrochloride salt or ester word | a salt with two molecules of hydrochloric acid for each molecule of the base | — | pramipexole dihydrochloride | WHO INNM, para. 8 and para. 17: di- counts two checked 2026-09-24 |
| dimesylate salt or ester word | a salt with two molecules of methanesulfonic acid for each molecule of the base | dimesilate WHO (INN) spelling | lisdexamfetamine dimesylate | WHO radicals list, entry mesilate (USAN: mesylate); di- counts two checked 2026-09-24 |
| dipotassium salt word | a salt with two potassium ions for each molecule of the medicine | dipotassium clorazepate WHO order: the metal word comes first when the INN is an acid; US labels put it last | clorazepate dipotassium | WHO INNM, para. 10: disodium tiludronate checked 2026-09-24 |
| dipropionate salt or ester word | an ester with two propionic acid groups | — | beclomethasone dipropionate | WHO INNM, para. 17: with two radicals the prefix di- goes before the radical name checked 2026-09-24 |
| disodium salt word | a salt with two sodium ions for each molecule of the medicine | disodium pamidronate WHO order puts the metal first; US labels put it last | pamidronate disodium | WHO INNM, para. 10: disodium tiludronate checked 2026-09-24 |
| edisylate salt or ester word | a salt of ethane-1,2-disulfonic acid; the US spelling of WHO's edisilate | edisilate WHO (INN) spelling | prochlorperazine edisylate | WHO radicals list, entry edisilate (USAN: edisylate); also INNM para. 7 checked 2026-09-24 |
| erbumine salt word | a salt with the base 2-methylpropan-2-amine (tert-butylamine); erbumine is WHO's short name for it | — | perindopril erbumine | WHO INNM, paras. 9 and 12: perindopril erbumine checked 2026-09-24 |
| esylate salt or ester word | a salt of ethanesulfonic acid; the US spelling of WHO's esilate | esilate WHO (INN) spelling | nintedanib esylate | WHO radicals list, entry esilate (USAN: esylate) checked 2026-09-24 |
| ethyl ester group | an ethyl ester: the acid of the substance is joined with ethanol | — | icosapent ethyl | WHO INNM, para. 18: an alkyl radical word names the ester (methyl palmoxirate, butyl flufenamate) checked 2026-09-24 |
| fumarate salt or ester word | a salt of fumaric acid | — | quetiapine fumarate | WHO INNM, para. 8 checked 2026-09-24 |
| gluconate salt or ester word | a salt of gluconic acid | — | quinidine gluconate | WHO INNM, para. 8 checked 2026-09-24 |
| hcl shorthand | HCl is the chemical formula of hydrogen chloride; lists and labels write it as shorthand for hydrochloride | hydrochloride the word in the official name | metformin HCl | WHO INNM, para. 8: the official name spells out the acid (ondansetron hydrochloride dihydrate, para. 16) checked 2026-09-24 |
| hemifumarate salt or ester word | a salt with one molecule of fumaric acid for every two molecules of the medicine | — | aliskiren hemifumarate | WHO INNM, para. 8; hemi- counts one half, as in hemihydrate (para. 15) checked 2026-09-24 |
| hemihydrate water word | one molecule of water is bound for every two molecules of the substance | — | estradiol hemihydrate | WHO INNM, para. 15 checked 2026-09-24 |
| heptahydrate water word | seven molecules of water are bound to each unit of the substance | — | sodium phosphate, dibasic, heptahydrate | WHO INNM, para. 14: a Latin or Greek prefix gives the number of water molecules checked 2026-09-24 |
| hyclate water word | a hydrochloride that also carries ethanol and water: ethanol, hydrogen chloride and water in the ratio 0.5 : 1 : 0.5 | — | doxycycline hyclate | WHO INNM, paras. 14 and 16: doxycycline hyclate checked 2026-09-24 |
| hydrobromide salt or ester word | a salt of hydrobromic acid, formed with a base | — | dextromethorphan hydrobromide | WHO INNM, para. 8 checked 2026-09-24 |
| hydrochloride salt or ester word | a salt of hydrochloric acid, formed with a base | HCl shorthand on some lists and labels | sertraline hydrochloride | WHO INNM, para. 16: ondansetron hydrochloride dihydrate checked 2026-09-24 |
| hydrogen part of the name itself | marks an acid salt in which one acid hydrogen remains (hydrogen tartrate, hydrogen sulfate); the decoder keeps it in the name | bi- the US form joins it to the anion: bitartrate, bisulfate | sodium hydrogen carbonate | WHO radicals list, entries such as aceglumate (hydrogen N-acetyl-L-glutamate) checked 2026-09-24 |
| iodide salt or ester word | the negative ion of the salt is iodide | — | echothiophate iodide | WHO INNM, paras. 8 and 23-24: the anion of a quaternary substance is named as a second word checked 2026-09-24 |
| lactate salt or ester word | a salt of lactic acid | — | milrinone lactate | WHO INNM, para. 16: ethacridine lactate monohydrate checked 2026-09-24 |
| lactobionate salt or ester word | a salt of lactobionic acid | — | erythromycin lactobionate | WHO INNM, section VI: erythromycin lactobionate checked 2026-09-24 |
| lithium salt word | the lithium salt of an acid | — | lithium carbonate | WHO INNM, para. 9: a simple cation takes its usual chemical name checked 2026-09-24 |
| magnesium salt word | the magnesium salt of a medicine that is itself the acid part | — | esomeprazole magnesium | WHO INNM, para. 10: magnesium valproate checked 2026-09-24 |
| malate salt or ester word | a salt of malic acid | — | sunitinib malate | WHO INNM, para. 8 checked 2026-09-24 |
| maleate salt or ester word | a salt of maleic acid | — | timolol maleate | WHO INNM, para. 8: timolol maleate checked 2026-09-24 |
| medoxomil ester group | an ester with the group (5-methyl-2-oxo-1,3-dioxol-4-yl)methyl, a short name WHO coined for it | — | olmesartan medoxomil | WHO radicals list, entry medoxomil checked 2026-09-24 |
| meglumine salt word | a salt with the base meglumine (N-methylglucamine) | — | diatrizoate meglumine | WHO INNM, para. 11: gadopentate meglumine checked 2026-09-24 |
| mesilate salt or ester word | a salt of methanesulfonic acid; mesilate is WHO's short name for methanesulfonate | mesylate US (USAN) spelling | abanoquil mesilate | WHO radicals list, entry mesilate (USAN: mesylate); also INNM para. 7 checked 2026-09-24 |
| mesylate salt or ester word | a salt of methanesulfonic acid; the US spelling of WHO's mesilate | mesilate WHO (INN) spelling | imatinib mesylate | WHO radicals list, entry mesilate (USAN: mesylate) checked 2026-09-24 |
| methyl ester group | a methyl ester: the acid of the substance is joined with methanol | — | methyl aminolevulinate | WHO INNM, para. 18: methyl palmoxirate checked 2026-09-24 |
| mofetil ester group | an ester with the group 2-(morpholin-4-yl)ethyl, a short name WHO coined for it | — | mycophenolate mofetil | WHO INNM, para. 18: mycophenolate mofetil checked 2026-09-24 |
| monohydrate water word | one molecule of water is bound to each molecule of the substance | — | bosutinib monohydrate | WHO INNM, para. 15: niclosamide monohydrate checked 2026-09-24 |
| napsylate salt or ester word | a salt of naphthalene-2-sulfonic acid; the US spelling of WHO's napsilate | napsilate WHO (INN) spelling | propoxyphene napsylate | WHO radicals list, entry napsilate (USAN: napsylate) checked 2026-09-24 |
| nitrate salt or ester word | a salt of nitric acid | — | miconazole nitrate | WHO INNM, para. 8 checked 2026-09-24 |
| oxalate salt or ester word | a salt of oxalic acid | — | escitalopram oxalate | WHO INNM, para. 8 checked 2026-09-24 |
| pamoate salt or ester word | a salt of pamoic acid, 4,4'-methylenebis(3-hydroxynaphthalene-2-carboxylic acid); the US name of WHO's embonate | embonate WHO (INN) name for the same anion | hydroxyzine pamoate | WHO radicals list, entry embonate (USAN: pamoate); also INNM para. 7 checked 2026-09-24 |
| pegol part of the name itself | the second word of a two-word INN for a substance carrying a polyethylene glycol (polyoxyethylene) chain; the decoder keeps it in the name | peg- the same chain can instead be named by a peg- prefix or -peg- infix | certolizumab pegol | WHO radicals list, introduction and Annex 5 (names with pegol as second word) checked 2026-09-24 |
| phosphate salt or ester word | a salt or ester of phosphoric acid | — | oseltamivir phosphate | WHO INNM, para. 8: prednisolone sodium phosphate checked 2026-09-24 |
| potassium salt word | the potassium salt of a medicine that is itself the acid part | — | losartan potassium | WHO INNM, para. 10: potassium clavulanate checked 2026-09-24 |
| propionate salt or ester word | an ester or salt of propionic (propanoic) acid | — | fluticasone propionate | WHO INNM, para. 21: the INN of the alcohol stays and the acid becomes -ate checked 2026-09-24 |
| proxetil ester group | an ester with the group rac-1-{[(propan-2-yloxy)carbonyl]oxy}ethyl, a short name WHO coined for it | — | cefpodoxime proxetil | WHO INNM, para. 17 (table) and para. 19: cefpodoxim proxetil checked 2026-09-24 |
| sodium salt word | the sodium salt of a medicine that is itself the acid part | sodium valproate WHO order puts sodium first when the INN is an acid named with the word acid; US labels write valproate sodium | naproxen sodium | WHO INNM, paras. 10 and 12: sodium valproate, ibuprofen sodium checked 2026-09-24 |
| stearate salt or ester word | a salt or ester of stearic (octadecanoic) acid | — | erythromycin stearate | WHO INNM, section VI: erythromycin stearate checked 2026-09-24 |
| succinate salt or ester word | a salt or ester of succinic (butanedioic) acid | — | metoprolol succinate | WHO INNM, para. 8 checked 2026-09-24 |
| sulfate salt or ester word | a salt or ester of sulfuric acid | sulphate older British spelling; WHO and US names write sulfate | hydroxychloroquine sulfate | WHO INNM, para. 8; WHO writes sulfate (laurilsulfate = dodecyl sulfate, para. 20) checked 2026-09-24 |
| sulphate salt or ester word | a salt or ester of sulfuric acid; the older British spelling of sulfate | sulfate WHO and US spelling | salbutamol sulphate | WHO INNM, para. 20: WHO writes sulfate (dodecyl sulfate) checked 2026-09-24 |
| tartrate salt or ester word | a salt of tartaric acid | — | metoprolol tartrate | WHO INNM, para. 8 checked 2026-09-24 |
| tosylate salt or ester word | a salt of 4-methylbenzene-1-sulfonic acid (toluenesulfonic acid); the US spelling of WHO's tosilate | tosilate WHO (INN) spelling | sorafenib tosylate | WHO radicals list, entry tosilate (USAN: tosylate) checked 2026-09-24 |
| trihydrate water word | three molecules of water are bound to each molecule of the substance | — | ampicillin trihydrate | WHO INNM, para. 14: a Latin or Greek prefix gives the number of water molecules checked 2026-09-24 |
| tromethamine salt word | a salt with the base 2-amino-2-(hydroxymethyl)propane-1,3-diol; the US name of WHO's trometamol | trometamol WHO (INN) name for the same base | ketorolac tromethamine | WHO INNM, paras. 12 and 25: dinoprost trometamol, dexketoprofen trometamol checked 2026-09-24 |
| valerate salt or ester word | an ester of valeric (pentanoic) acid | — | estradiol valerate | WHO INNM, para. 21: the INN of the alcohol stays and the acid becomes -ate checked 2026-09-24 |
| xinafoate salt or ester word | a salt of 1-hydroxynaphthalene-2-carboxylic acid; xinafoate is WHO's short name for it | — | salmeterol xinafoate | WHO radicals list, entry xinafoate; also INNM section VI: salmeterol xinafoate checked 2026-09-24 |
| zinc salt word | the zinc salt or zinc complex of a substance | — | bacitracin zinc | WHO INNM, para. 26: bacitracin zinc checked 2026-09-24 |
Since 2017 the US FDA names each biological product with a core name and a suffix: adalimumab-atto, infliximab-dyyb, insulin glargine-yfgn. For a new product the core name is the US adopted name (USAN), which for these products is usually the same as the WHO INN; FDA's examples are filgrastim and epoetin alfa. The suffix is, in the words of FDA's guidance, "a distinguishing suffix that is devoid of meaning and composed of four lowercase letters", joined to the core name with a hyphen. The letters are not an abbreviation of the maker, the country or anything else, so they cannot be decoded; they tell apart products that share a core name.
FDA asks that a proposed suffix be unique, be four lowercase letters of which at least three are different, and carry no meaning. It must not contain numerals, suggest a drug substance or core name, look like the name of a marketed product or of the licence holder, or be too close to another FDA suffix.
In FDA's own data. In the copy of FDA's Drugs@FDA data this site uses (checked 2026-09-23), 218 ingredient names end in a hyphen and four letters, on 149 different core names. Adalimumab has ten: -aacf, -aaty, -adaz, -adbm, -afzb, -aqvh, -atto, -bwwd, -fkjp and -ryvk; denosumab also has ten. The suffix is not only on later products: avalglucosidase alfa-ngpt (Nexviazyme) is a new medicine, not a version of an earlier one. Some older products are still listed under the plain name: Drugs@FDA gives Humira as adalimumab and Remicade as infliximab, next to Amjevita as adalimumab-atto and Inflectra as infliximab-dyyb.
Outside the US these suffixes are not part of the name: the WHO INN is adalimumab alone. The decoder sets the four letters aside and reads the stem in the core name (-mab).
Source: Nonproprietary Naming of Biological Products: Guidance for Industry, US Food and Drug Administration, January 2017 (docket FDA-2013-D-1543; PDF), sections III and VI; checked 2026-09-24.
From the 1990s WHO ended every monoclonal antibody INN in -mab (adalimumab, pembrolizumab). At its 73rd INN Consultation, in October 2021, WHO's INN Expert Group stopped using -mab for new names and split the group into four endings: three for antibodies that bind one target (monospecific) and one for antibodies that bind more than one. Names given earlier keep -mab. As before, a syllable just before the ending names the target class.
unmodified immunoglobulins (current monoclonal antibody naming scheme)
Monospecific full-length immunoglobulins whose constant regions are left as a naturally occurring allele encodes them. Chimeric and humanized antibodies go here too.
Examples from WHO's list: becotatug, belrestotug, calpurbatug. All 34 -tug names
artificial immunoglobulins (current monoclonal antibody naming scheme)
Monospecific full-length immunoglobulins with engineered amino-acid changes anywhere in the constant regions, such as a changed hinge or an added glycan site.
Examples from WHO's list: anzurstobart, atisnolerbart, bempikibart. All 67 -bart names
multi-specific immunoglobulins (current monoclonal antibody naming scheme)
Bispecific and multispecific immunoglobulins, whatever their format, type or shape: binding to more than one target through different variable domains.
Examples from WHO's list: acimtamig, ciduvectamig, danvilostomig. All 19 -mig names
immunoglobulin fragments (current monoclonal antibody naming scheme)
Monospecific fragments of any kind that are not -tug or -bart: at least one variable domain that binds, with a complete, partial or absent constant region (for example constructs without an Fc domain, or scFv-Fc constructs).
No example yet: WHO's 2024 stem book lists no INN under -ment in Part IV, so this site has no -ment stem page and the decoder does not read -ment yet.
Sources: New INN nomenclature scheme for monoclonal antibodies, WHO INN Working Doc. 22.542, May 2022 (checked 2026-09-24), for the scheme and what each ending covers; the definitions and example names are from WHO's stem book 2024 (see sources).
Words outside the list. The decoder sets aside only the 74 words in the table. Others, such as decanoate, enantate, pivalate or olamine, are read as part of the name. Names made only of salt words, such as lithium carbonate or sodium chloride, are read whole. The FDA suffix is split only when a hyphen and exactly four letters end the name and at least four letters come before the hyphen; the four letters are never looked up, because they mean nothing. -ment has no example yet, since WHO's 2024 stem book lists none.
The whole table is one file, salts.json, with a source and the date checked for every word.