Prescription line

Grammar and construction logic

The basis of the prescription line, or designatio materiarum (designation of substances), is a strict grammatical dependency. The logic of construction relies on a sequential chain of subordination. First, the physician addresses the pharmacist with the word Recipe (abbreviated as Rp. — take), which serves as the start of the line.

Directly related to this verb is the specified quantity of the drug (dose). It answers the question "how much?". Next comes the name of the medicinal substance itself. It grammatically depends on the dosage number, answers the question "of what?", and is therefore always placed in the genitive case — Genetivus.

There are strict capitalization rules: each new medicinal product must be prescribed on a separate, new line and with a capital letter. Within the line itself, only the names of medicinal substances and plant names are capitalized.

Rules for dosing solid and liquid forms

The approach to indicating the quantity strictly depends on the physical state of the drug and complies with established standards:

• Solid and soft medicinal forms (e.g., ointments, powders) are always prescribed in grams. The key rule here is that the word "gram" is completely omitted, and the number is formatted as a decimal fraction. Examples: 3.0; 2.5; 0.015. In a prescription, this looks like: Recipe: Unguenti Zinci 30.0 (Zinc ointment) or Recipe: Anaesthesini 0.3 (Anesthesin).
• Liquid medicinal forms are indicated predominantly in volume units, i.e., in milliliters (ml), although prescribing in grams is occasionally permitted. Examples of liquid form formatting: Recipe: Olei Vaselini 30 ml or Recipe: Extracti Crataegi fluidi 20 ml.
• Antibiotics have their own specifics — their dosage is usually indicated not in grams or milliliters, but in biological units of action, denoted by the standard abbreviation IU (e.g., Recipe: Benzylpenicillini-natrii 250,000 IU).

Specifics of prescribing drops

If the volume of the prescribed liquid agent is very small and amounts to less than 1 ml, it is dosed not in milliliters, but in drops. In this case, special grammatical and numerical rules apply.

First, the case changes. The word "drop" itself must be in the accusative case — Accusativus. Second, the grammatical form directly depends on the quantity:

• If exactly one drop is prescribed, the singular form is used — guttam. Example: Recipe: Solutionis Adrenalini hydrochloridi 0.1% guttam I.
• If there are several drops, the plural form is used — guttas. Example: Recipe: Olei Menthae piperitae guttas V.

Third, the numerical designation of the number of drops is always indicated exclusively with a Roman numeral, which is placed after the word guttam or guttas.

Identical dosages and line wrapping

Often in a prescription, two or more medicinal substances are prescribed consecutively in absolutely identical quantities. To avoid repeating the same number, the dose is indicated only once — strictly after the name of the last drug in this list. Before this number, the word ana (translated as "of each") must be placed. Example: Tincturae Valerianae, then on a new line Tincturae Convallariae ana 7.5 ml (tincture of valerian and tincture of lily of the valley, 7.5 ml of each).

It is also important to format long entries correctly. If the name of the drug or the entire entry does not fit on one line, it is wrapped to the next. The main rule when wrapping: an indent from the beginning of the line must be made so that the dosage designation is always clearly positioned on the right side of the prescription.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Genetivus endings for different declensions in Latin.
• Formatting the Signa section (signature) and patient instructions.
• Standard prescription abbreviations: what is permitted and what is prohibited.
• Specifics of prescribing complex mixtures and herbal preparations.

Other topics in the section "Accusativus and Ablativus. Prepositions. Prescription. Prescription Line"

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