How common stems work
In the International Nonproprietary Name (INN) system, special frequency segments are used to group drugs, also referred to as common stems (in English, common stems). The official INN lists are regularly supplemented with directories of such elements in Latin and English.
The main task of these segments is to show the specialist that a drug belongs to a specific category. The choice of a particular stem is based on strict criteria. It must reflect:
- Pharmacological action of the substance;
- Features of its chemical structure;
- The source from which the drug was obtained.
Interestingly, there is a strict rule when creating names: words must not associate in patients' minds with anatomy, physiological processes, specific diseases, or direct therapeutic effects. Examples of common stems: the drug Vinblastinum contains the stem vin-, indicating its origin (alkaloid from the periwinkle plant — Vinca), while Pinazepamum contains the element -azepamum, reflecting its structure (a diazepam derivative).
Enzymes, analgesics, and antispasmodics
Frequency segments allow for the unmistakable recognition of drugs used for pain relief, spasmolysis, and the regulation of enzymatic reactions.
| Stem (Lat.) | Drug group | Note |
|---|---|---|
| -cainum | Local anesthetics | Local anesthetics |
| -adolum | Analgesics | Analgesics. In the example: Betamethadolum |
| -verinum | Antispasmodics | Have a papaverine-like effect |
| -as- | Enzymes | Indicates enzymes |
| -stat- | Enzyme inhibitors | Inhibit processes (from Lat. inhibeo — to restrain) |
Antibiotics and antimicrobials
A vast layer of pharmaceutical names is associated with the treatment of infections. Here, common stems often indicate the chemical group or the source of origin of the antibacterial substance.
- -cef- (or -ceph-) — unites antibiotics belonging to the cephalosporin group.
- -cillinum — a marker for classic penicillin-class antibiotics.
- -cyclinum — indicates belonging to tetracyclines and oxytetracyclines.
- -mycinum — historically denotes antibiotics produced by actinomycetes (primarily Streptomyces strains). Later, this base began to be used for other natural or synthetic antibiotics.
- -sulfa- — anti-infective antimicrobial sulfonamides (in INN lists they also appear as sulfonamides).
- vir — a short stem used to designate antiviral drugs.
Hormones, metabolic regulators, and diagnostics
The names of hormonal and metabolic agents are built according to the same systematic rules. Male sex hormones (androgenic steroids) are marked with the stems -andr-, -stan-, or -ster-. Estrogenic drugs, i.e., female sex hormones, must contain the element -(o)estr-. Corticosteroids are recognized by the stem cort, though it is important to remember that this rule does not apply to prednisolone derivatives. Active biogenic compounds — prostaglandins — include the stem prost.
Drugs affecting metabolism, such as blood glucose-lowering hypoglycemic sulfonamides, contain the element gly- (or gli-). Antihistamines are easily recognized by the stem -astinum.
Radiopaque agents are used in diagnostic radiology, and radiopharmaceuticals in therapy. If they contain iodine in their composition, their names include the characteristic stems -iod- or -io-.
Many stems are connected to Latin and Greek roots. For example, -adolum is easy to remember via the Latin dolor (pain) — these are analgesics, while -astinum (antihistamines) can be remembered via the Greek histos (tissue).
Class and exam questions
What do common stems reflect in the INN system?
They indicate the pharmacological action of the drug, the features of its chemical structure, or its natural source.
What should not be present in a drug name according to INN rules?
It is recommended to avoid direct references to anatomical organs, pathological conditions, physiological processes, or direct therapeutic effects in drug names.
How do the stems -cainum and -adolum differ?
The stem -cainum indicates local anesthetics (substances numbing a specific area), while -adolum indicates analgesics (drugs systematically relieving pain).
What else to study on this topic
- Features of the classification of actinomycetes in the isolation of -mycinum group antibiotics
- Exceptions in corticosteroid nomenclature: why prednisolone derivatives do not contain the stem cort
- Substances that delay the course of physiological or physicochemical processes
- Etymology and origin of the name histamine from the Greek word histos
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