Drug names

Main rule: drugs in -um (second declension)

The vast majority of International Nonproprietary Names (INN) of medicinal substances in Latin have a standardized ending -um. Grammatically, these terms belong to the second declension and are neuter (indicated in dictionary entries by the letter n — neutrum).

The dictionary form of such drugs always specifies the genitive case ending (Genetivus) — -i. This largest group includes antibiotics, alkaloids, carbohydrates, hormonal agents, and synthetic drugs. Here are typical representatives of this class from the lexical minimum:

• Aethylmorphinum, i n — ethylmorphine;
• Atropinum, i n — atropine;
• Benzylpenicillinum, i n — benzylpenicillin;
• Codeinum, i n — codeine;
• Ephedrinum, i n — ephedrine;
• Glucosum, i n — glucose;
• Lincomycinum, i n — lincomycin;
• Morphinum, i n — morphine;
• Oleandomycinum, i n — oleandomycin;
• Phenobarbitalum, i n — phenobarbital;
• Phenoxymethylpenicillinum, i n — phenoxymethylpenicillin;
• Pilocarpinum, i n — pilocarpine;
• Platyphyllinum, i n — platyphylline;
• Rutinum, i n — rutin;
• Streptocidum, i n — streptocide;
• Strychninum, i n — strychnine;
• Synoestrolum, i n — synestrol;
• Theophyllinum, i n — theophylline;
• Thiaminum, i n — thiamine;
• Vinylinum, i n — vinylilin;
• Mentholum, i n — menthol (genitive case — Mentholi).

Also within the second declension, there is an important orthographic feature: some substances end in -ium. In this case, the genitive ending is -ii. A prime example of this rule is Chloroformium, ii n (chloroform).

Exceptions: first declension drugs in -a

Despite the fact that most agents are neuter, medical practice features drugs whose names traditionally end in -a. They grammatically follow the rules of the first declension and are feminine (f — femininum).

A classic example of this category is Camphŏra, ae f — camphor. In the genitive case, the ending predictably changes to -ae (Camphorae). Knowing this exception is critical when writing prescriptions, as the agreement of adjectives and other prescription line components will strictly follow feminine gender rules. The root word for one of the vegetable oils follows the same word-formation model — Oliva, ae f (olive).

Nomenclature of complex salts and esters

The formation of complex salt names requires special attention to the genitive case. In such chemical constructions, anion names often function as masculine third-declension nouns (designated in dictionaries as m — masculinum).

If an anion has the ending -as in the nominative case (Nominativus), it always transforms into -atis in the genitive. Let us examine key examples from chemical nomenclature:

• Methylii salicylas (methyl salicylate) transforms in the genitive case to Methylii salicylatis;
• Phenylii salicylas (phenyl salicylate) changes to Phenylii salicylatis;
• Calcii pantothenas (calcium pantothenate) shifts to Calcii pantothenatis;
• Oleandomycini phosphas (oleandomycin phosphate) becomes Oleandomycini phosphatis.

Pharmaceutical terminology also actively uses other third-declension anion names following a similar rule: glycerophosphas, atis m (glycerophosphate), hydrotartras, atis m (hydrotartrate), and thiosulfas, atis m (thiosulfate).

Combined salts written with a hyphen deserve separate mention. For example, Coffeinum-natrii benzoas (caffeine-sodium benzoate). When declining such constructions, the respective components change: Coffeini-natrii benzoatis.

For other types of salts (e.g., halides or cyanides), the basic second declension applies: Thiamini bromidum (thiamine bromide, genitive — Thiamini bromidi), Hydrargyri oxycyanidum (mercury oxycyanide, genitive — Hydrargyri oxycyanidi).

Oils, solutions, and dyes

Liquid dosage forms and various oils frequently appear in prescriptions. For oils, the noun oleum (oil, neuter, second declension) is always used, followed strictly by the plant name or source substance in the genitive case.

Basic examples of oils:

1. Sunflower oil — oleum Helianthi (in the genitive case of the entire construction, the word oleum changes: olei Helianthi).
2. Olive oil — oleum Olivarum (derived from the plural noun for olives).
3. Vaseline oil — oleum Vaselini (genitive case — olei Vaselini).

When referring to solutions, the word Solutio is used, followed by the active substance name also in the genitive case. For example, Solutio Glucosi (glucose solution, genitive case of the phrase — Solutionis Glucosi).

Certain substances have compound names including adjectives. The well-known dye methylene blue is translated as Methylenum coeruleum (in the genitive case, both words decline according to the second declension: Methyleni coerulei). Prescriptions may also use the adjective isotonicus, a, um (isotonic), which belongs to the 1st-2nd declension and always agrees with the modified noun in gender, number, and case.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Orthographic features of writing Latin alkaloids and antibiotics.
• Full chemical nomenclature: oxides, acids, and halides in medical prescriptions.
• Rules of grammatical agreement of adjectives with pharmaceutical form names (e.g., isotonicus).
• Declension of multi-component drugs and complex chemical compounds.
• Differences between the first and second declension nouns in basic pharmaceutics.

Other topics in the "Salt Names" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.