DƯỢC LÍ Goodman & Gilman's The Pharmacological Basis of Therapeutics 12th, 2010

Principles of Prescription Order
Writing and Patient Compliance
Iain L. O. Buxton
From the wrong drug prescribed to the wrong dosage or
administration schedule advised, dispensed, or administered,
the impact of medication misadventures is a costly
problem. Errors of these sorts occur because human
beings are involved, and such errors can be prevented
only by systems that make it difficult to do the wrong
thing. This appendix provides a primer on the proper
approach to the medication prescription and order
process and a resource for practitioners in effectively
providing pharmaceutical care for their patients.
THE MECH ANICS OF PRESCRIPTION
ORDER WRITING
History
Early medicines were made up of multiple ingredients
requiring complex preparation, and Latin was adopted
as the standard language of the prescription to ensure
understanding between physician and pharmacist and
consistency in pharmaceutical composition. Latin no
longer is the international language of medicine, but a
number of commonly used abbreviations derive from
old Latin usage. The symbol “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.
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. The subscription
is the instruction to the pharmacist, usually
consisting of a short sentence such as: “make a solution,”
“mix and place into 30 capsules,” or “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; for example, “1 cap tid pc,” will be interpreted
by the pharmacist as “take one capsule three
times daily after meals.” However, the use of Latin
abbreviations for these directions only mystifies the
prescription and is discouraged. This can be a hindrance
to proper patient-physician communication and is an
otherwise unnecessary source of potential dispensing
errors. Because the pharmacist always writes the label
in English (or, as appropriate, in the language of the
patient), the use of such abbreviations or symbols is
unnecessary. Many serious dispensing errors can be
traced to the use of abbreviations (Cohen, 2007).
The instruction “take as directed” is not satisfactory
and should be avoided by the physician. Such directions
assume an understanding on the part of the patient
that may not be realized and inappropriately exclude the
pharmacist from the pharmaceutical care process. Such
directions are inadequate for the pharmacist, who must
determine the intent of the physician before dispensing
the medication, and who shares the responsibility for the
patient’s safe and proper use of the medication. The best
directions to the patient will include a reminder of the