Of stems and endings: the system behind drug names

While trade names often attract the atten­tion of marketers and pati­ents, the greater benefit for medical prac­tice lies in the logic of Inter­na­tional Nonpro­prie­tary Names (INNs). These are not only unified iden­ti­fiers, but also convey phar­ma­co­lo­gical infor­ma­tion – a kind of ‘lingu­i­stic coding’.
Clas­si­fi­ca­tion by name stems
Many INN endings have a signal­ling func­tion and make orien­ta­tion easier:
‑olol = beta blockers (meto­prolol, bisoprolol)
‑pril = ACE inhi­bi­tors (enalapril, lisinopril)
‑sartan = AT1 antago­nists (vals­artan, losartan)
‑mab = mono­clonal anti­bo­dies (adali­mumab, trastuzumab)
‑tinib = tyro­sine kinase inhi­bi­tors (imat­inib, osimertinib)
Parti­cu­larly in the case of onco­lo­gical agents, where new subs­tances are approved every year, this syste­matic struc­ture is an important tool for clas­si­fying the mecha­nism of action at least roughly. Of course, the full thera­peutic context must be further differentiated.
Diffe­ren­tia­tion and pitfalls
However, the nomen­cla­ture is not always intui­tive. Suffixes such as ‑ximab (chimeric mAbs) or ‑zumab (huma­nised mAbs) repre­sent subtle struc­tural diffe­rences that are clini­cally rele­vant, for example in terms of immu­no­ge­ni­city. The situa­tion regar­ding ‑tinibs is similar: not every tyro­sine kinase inhi­bitor attacks the same target, even if the name suggests that the subs­tances are closely related.
In addi­tion, similar-sounding names carry risks: hydralazine versus hydro­xy­zine, cele­coxib versus Celexa® (citalo­pram, USA). Inter­na­tional autho­ri­ties such as the EMA and FDA ther­e­fore strictly check for possible confu­sion, but in clinical reality, ‘look-alike, sound-alike drugs’ remain an issue – with docu­mented medi­ca­tion errors.
Bene­fits in ever­yday medical practice
Espe­ci­ally in hospital settings, where trade names can vary depen­ding on the country or even the hospital form, orien­ta­tion via INN endings is often the more reliable stra­tegy. A ward doctor imme­dia­tely reco­g­nises that a drug ending in ‑pril or ‑sartan belongs to anti­hy­per­ten­sive therapy – even if he has never encoun­tered the brand name before.
Lingu­i­stic balance
A recur­ring topic in WHO expert commit­tees is the tension between precision and prac­ti­cality. Tongue twis­ters such as ‘obinu­tu­zumab’ are scien­ti­fi­cally correct, but not very user-friendly in ever­yday life. This is where the balan­cing act comes in: as much infor­ma­tion as neces­sary, as concise as possible.
When names make a big impres­sion: Tall Man lettering
A some­what uncon­ven­tional but very effec­tive trick in drug nomen­cla­ture is Tall Man lette­ring. This involves deli­bera­tely capi­ta­li­sing certain letters in an active ingre­dient name – for example, pred­ni­SONE and predn­iSO­LONE. The emphasis is intended to make similar-looking names more distin­gu­is­hable and thus prevent medi­ca­tion errors.
And why is it called ‘Tall Man’? Quite lite­rally: the large letters ‘stand out’ like tall people in a crowd – they are not easily over­looked. This is intended to help doctors and phar­macists reco­g­nise more quickly in ever­yday life that these are two diffe­rent substances.
Conclusion
For doctors, drug names are more than just labels – they are tools for orien­ta­tion. Name stems enable quick clas­si­fi­ca­tion, endings often reveal the mecha­nism of action, and diffe­rences in syll­ables can have clinical rele­vance. Those who are fami­liar with the system have an advan­tage: in reco­g­nising new subs­tances, avoi­ding confu­sion and quickly trans­fer­ring guide­lines into prescrip­tion prac­tice. And if neces­sary, CAPI­TA­LI­SA­TION helps…