Designation of doses in prescriptions

Grammar in Prescription Writing: Two Paths of a Single Command

Traditionally, prescriptions use two completely equivalent grammatical structures to convey instructions to the pharmacist. The choice between them depends on established practice, but functionally they are equivalent.

1. Imperative Mood (Imperativus). Represents a direct, clear command. A classic example of such a formulation is Misce, da, signa, which translates as "Mix, dispense, label".
2. Subjunctive Mood (Conjunctivus). In this case, a passive construction is used, translating with the word "let". Example: Misceatur, detur, signetur, which means "Let it be mixed, dispensed, labeled".

Analysis of the Phrase "Dispense Such Doses"

One of the most frequent phrases in prescription writing is the instruction to dispense a specific quantity of a drug. This phrase also follows the rule of two moods.

• If the imperative mood is used, the phrase sounds like Da tales doses (Dispense such doses). Here, the verb da is in the direct command form.
• If the subjunctive mood is used, the phrase changes to Dentur tales doses (Let such doses be dispensed). In this construction, the verb dentur is in the passive voice (Passivum).

Important rule: the verb dentur strictly agrees with the word doses (doses) in the plural.

Structure of the Subscription and Designation

Any prescription consists of several mandatory blocks. After listing the ingredients and their quantities (in grams, milliliters, or drops), two important parts follow:

• Subscription (Subscription). This is the instruction for the pharmacist on what dosage form to prepare and how many doses to dispense.
• Signatura (Designation). This is the instruction for the patient indicating the method of administration. In prescriptions, this part is often abbreviated to the word "Label" or "Sign".

Drafting Solid Dosage Forms

When prescribing complex divided powders (e.g., containing platyphylline hydrotartrate, sodium bromide, and caffeine-sodium benzoate, or belladonna extract, bismuth subnitrate, and phenyl salicylate), the subscription must indicate the manufacturing process: "Mix to form a powder". Only after this is "Let 12 (or 10) such doses be dispensed" written.

For capsules and tablets, the mixing process is usually not indicated. The dosage form is added to the quantity:

• For lincomycin hydrochloride: "Dispense 20 such doses in capsules".
• For paracetamol or complex tablets with calcium glycerophosphate and lactate: "Dispense 10 (or 20) such doses in tablets".
• For pentoxyl tablets, it must be specified that they are film-coated.

Drafting Liquid, Soft Forms, and Suppositories

Liquid and soft forms require their own formulations:

• Mixtures. Active substances (e.g., sodium salicylate, potassium iodide), drops (5% alcoholic iodine solution — 6 drops), and solvent (distilled water up to 200 ml) are listed. The subscription looks concise: "Mix. Dispense. Label".
• Liniments. For mixtures (e.g., of castor oil, xeroform, and vinylin), the subscription requires specifying the form: "Mix to form a liniment. Dispense".
• Suppositories. Suppositories (e.g., with methyluracil) are prescribed simply: the name, dosage, and the phrase "Dispense 10 such doses" are indicated.

Variants of Manufactured Forms

The construction "Mix to form..." is universal for extemporaneous compounding (medicines prepared in the pharmacy). Depending on the ingredients, the pharmacist may be instructed to prepare different forms. Possible translation variants include:

• let a powder be formed;
• let a liniment be formed;
• let a solution be formed;
• let an ointment be formed;
• let an infusion be formed.

The choice always depends on the starting components. For example, castor oil and xeroform will yield a liniment, while belladonna extract and bismuth nitrate will yield a powder.

Class and exam questions

What else to study on this topic

• Rules for translating complex divided powders into Latin
• Features of prescribing film-coated tablets
• Grammar for drafting liquid dosage forms (mixtures and liniments)
• Specifics of indicating drops and percentages in prescription formulas
• Prescribing finished dosage forms using suppositories as an example

Other topics in the section "Prescription abbreviations. Frequency stems"

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