Liquid dosage forms: oily solution in ampoules
When prescribing hormonal drugs, liquid forms are often used, in particular, solutions for injections. Let's consider an example of prescribing an oily solution.
In the Designatio materiarum section (listing of substances), the physician is obliged to indicate the following parameters:
- The name of the drug itself (in this case, it is desoxycortone acetate solution).
- The nature of the solvent used. For this hormonal drug, the solvent is oil, so the solution is classified as oily (rather than aqueous or alcoholic).
- The dosage of the drug, which is expressed through concentration. In our example, it is 0.5%.
- The volume of a single ampoule, which is equal to 1 ml.
The next block is Subscriptio (instructions to the pharmacist). Here, the physician gives clear dispensing instructions: it is necessary to dispense 10 such doses. The type of packaging must also be specified — the drug must be dispensed in ampoules.
The prescription ends with the Signatura (designation). This is a special place in the prescription intended exclusively for indicating the method of administration of the drug by the patient (or medical staff) themselves, rather than for information about the shelf life or dosage.
Solid undosed dosage forms: medicinal herbal teas
A medicinal herbal tea (Species) represents a solid undosed dosage form. Most often, herbal teas are prescribed as a mixture of medicinal plant raw materials, which is subsequently used to prepare aqueous extracts — infusions or decoctions (but not suspensions, emulsions, or alcoholic tinctures).
The structure of Designatio materiarum when prescribing a herbal tea has a complex multi-component character:
- Basis (main substance). This is the main active component. In our example, this role is played by St. John's wort herb in the amount of 20.0 g.
- Adjuvans (auxiliary or additional substance). Enhances or complements the action of the basis. Here, these are sage leaves in a volume of 30.0 g.
- Corrigens (correcting substance). Used to improve taste or odor. In this herbal tea, these are peppermint leaves — 10.0 g.
In the Subscriptio section for an undosed herbal tea, the physician prescribes a technological operation for the pharmacist: "Mix." This is followed by the target indication of the form: "let a herbal tea be made." The block ends with the standard command for dispensing the drug — "Dispense."
The Signatura section in the case of herbal teas performs a dual function: here is the place to indicate not only the method of administration, but also a detailed method for the patient to independently prepare the infusion at home.
Solid dosed dosage forms: compound powder
If a drug is prescribed in divided (dosed) portions and contains more than one component, such a form is called a compound powder. Let's consider a prescription example where the active substance requires the addition of a filler to create the required mass.
In the Designatio materiarum block, two key elements are indicated:
- Basis (active substance). In this case, it is bendazol. Since the powder is dosed, the exact single dose is indicated — 0.005 g.
- Constituens (form-forming substance or filler). Since the mass of the basis is too small for convenient administration, a filler is used, the role of which is played by sugar in the amount of 0.3 g per single dose. The filler is not a solvent, ointment base, or corrigent.
In the Subscriptio part, the physician again gives an instruction for the technological operation: "Mix, let a powder be made" (not "strain" and not "infuse"). Then the exact number of doses that the pharmacy must prepare and hand over to the patient is indicated: "Dispense such doses in the number of 20."
Finally, in the Signatura part, space is traditionally left to indicate the detailed administration scheme of the finished powders by the patient.
General patterns of prescription structure
Based on the analyzed examples, a strict sequence of prescription design can be distinguished:
- Listing of substances (Designatio materiarum) — describes what the drug consists of, determines the roles of the components (Basis, Adjuvans, Corrigens, Constituens) and their amount or concentration.
- Instruction to the pharmacist (Subscriptio) — contains command verbs (mix, dispense), determines the target dosage form (powder, herbal tea) and the type of packaging (ampoules).
- Designation (Signatura) — translates medical instructions into an instruction on preparation and drug administration scheme that is understandable to the patient.
Briefly: answers to topical questions
How are standard commands to the pharmacist written in Latin in the Subscriptio section?
In the Subscriptio section, standard commands to the pharmacist are written in Latin in the imperative or subjunctive mood. For example: Misce, fiat pulvis — mix, let a powder be made; Misce, fiat unguentum — mix, let an ointment be made; Misce, fiant species — mix, let a herbal tea be made. The command to dispense the drug is written as Da, for example, Da tales doses numero 20 — dispense such doses in the number of 20. The type of packaging may also be indicated, for example, in ampullis — in ampoules.
In which case are the names of drugs and plants written in Designatio materiarum?
In the Designatio materiarum section, the names of drugs and plants are written in the genitive case (Genitivus), except for cases of using abbreviated prescriptions of a complex composition, where the dosage form is written in the accusative case, and the active agents in the instrumental case. In standard structures with a dosage form, the name of the main substance or plant follows the name of the form in the genitive case with a capital letter.
What standard prescription abbreviations are used in the Subscriptio part?
In the Subscriptio part, standard generally accepted abbreviations of prescription formulations are used, for example, D.S. (Da. Signa. — dispense, designate), D.t.d. (Da tales doses — dispense such doses) and M.f. (Misce, fiat — mix, let be made).
What liquid dosage forms exist?
Educational materials highlight various liquid dosage forms intended for internal, external, or parenteral use. These include solutions, including oily and alcoholic ones, medicinal syrups, which are a concentrated solution of various sugars, as well as liquid extracts. In addition, heterogeneous liquid dosage forms are considered, such as suspensions, which are dispersions of insoluble solids in water, oil, glycerin, or alcohol, and emulsions, which are dispersions of oil in water.
To remember the roles of substances in a complex prescription (like in a herbal tea or powder), use the BACF acronym: Basis (base), Adjuvant (addition), Corrigent (taste correction), Former (Constituens — creation of mass).
Class and exam questions
What is a medicinal herbal tea (species) prescribed for?
Medicinal plant raw material in the form of a herbal tea is prescribed so that the patient can independently prepare an infusion or decoction from it.
What role does sugar play when prescribing bendazol in powders?
Sugar in a complex dosed powder plays the role of Constituens — a form-forming substance (filler), since the single dose of bendazol itself is very small (0.005 g).
What commands are written in the Subscriptio when prescribing a herbal tea?
In the instruction to the pharmacist, the technological operation "Mix", the target form "let a herbal tea be made", and the dispensing command "Dispense" are indicated.
What else to study on this topic
- Rules for converting percentage concentration into mass fractions when prescribing
- Differences in prescribing aqueous, alcoholic, and oily solutions
- Technology for preparing infusions and decoctions from herbal raw materials
- Rules for selecting excipients (Constituens) for various dosage forms
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