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ACE: angiotensin-converting enzyme

CAS: Chemical Abstract Service

CSA: Controlled Substances Act

DEA: Drug Enforcement Agency

DO: doctor of osteopathy

DTC: direct-to-consumer

FDA: Food and Drug Administration

IOM: Institute of Medicine

ISMP: Institute for Safe Medication Practices

MD: doctor of medicine

NDC: National Drug Code

PA: physician’s assistant

RN: registry number

USAN: U.S. Adopted Name

USP: U.S. Pharmacopeia

USP MERP: U.S. Pharmacopeia Medication Errors Reporting Program

USP/NF: USP/National Formulary


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. Non utuntur Latini.

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.

Who Can Prescribe Medicines?

Prescription writing in the U.S. is regulated by state boards of pharmacy. In many states, healthcare practitioners other than MD and DO physicians can write prescriptions, although in some cases narcotics are excluded. Licensed dentists, podiatrists, PAs, nurse practitioners, pharmacists, and clinical psychologists can prescribe medications under various circumstances.

Current Practice

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). 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.

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/d (1.4 mg/kg/d), whereas for treatment of congestive heart failure, the dose of this angiotensin II receptor antagonist generally should not exceed 50 mg/d. 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.

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