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In writing prescriptions, use English (in the U.S.) or the dominant language of the patient. Latin is no longer the international language of medicine, but a number of commonly used abbreviations derive from obsolete Latin usage and persist in prescription writing. Avoid using them.

Some Latin seems firmly embedded in pharmacy practice. "Rx" is said to be an abbreviation for the Latin word recipere, meaning "take" or "take thus," as a direction to a pharmacist, preceding the physician's "recipe" for preparing a medication. The abbreviation "Sig" for the Latin Signatura, is used on the prescription to mark the directions for administration of the medication.


In many states in the U.S., healthcare practitioners other than M.D. and D.O. physicians can write prescriptions. Licensed physician's assistants (P.A.), nurse practitioners, pharmacists, and clinical psychologists can prescribe medications under various circumstances.


The prescription consists of the superscription, the inscription, the subscription, the signa, and the name and signature of the prescriber, all contained on a single form (Figure AI–1).

Figure AI–1

The prescription. The prescription must be accurately and legibly prepared to identify the patient, the medication to be dispensed, and the mode of drug administration. Avoid abbreviations and Latin; they lead to dispensing errors. Include the therapeutic purpose in the subscription (e.g., "for control of blood pressure") to prevent errors in dispensing. For example, the use of losartan for the treatment of hypertension may require 100 mg/day (1.4 mg/kg/day), whereas for treatment of congestive heart failure, the dose of this AngII receptor antagonist generally should not exceed 50 mg/day. Including the therapeutic purpose of the prescription also can assist patients in organizing and understanding their medications. Including the patient's weight on the prescription can be useful in avoiding dosing errors, particularly when drugs are administered to children.

The superscription includes the date the prescription order is written; the name, address, weight, and age of the patient; and the Rx (Take). The body of the prescription, or inscription, contains the name and amount or strength of the drug to be dispensed, or the name and strength of each ingredient to be compounded.

The subscription is the instruction to the pharmacist, usually consisting of a short sentence such as: "dispense 30 tablets." The signa or "Sig" is the instruction for the patient as to how to take the prescription, interpreted and transposed onto the prescription label by the pharmacist. In the U.S., prescriptions should always be written in English. Many physicians continue to use Latin abbreviations; e.g., "1 cap tid pc," will be interpreted by the pharmacist as "take one ...

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