Drug, prescription: A drug
requiring a prescription, as opposed to an over-the-counter drug, which can be
purchased without one. The word "prescription" comes from the Latin
"praescriptus" compounded from "prae", before + scribere, to write =
to write before. Historically, a prescription was written before the
drug was prepared and
A prescription has several parts. There are:
- The superscription (or heading) with the symbol R or
Rx which stands for the word Recipe, meaning (in Latin) to take;
- The inscription which contains the names and
quantities of the ingredients;
- The subscription or directions for compounding the
- The signature which is often preceded by the sign s. standing for
signa, mark, giving the directions to be marked on the
Seen on a prescription, b.i.d. means twice
(two times) a day. It is an abbreviation for "bis in die" which in
Latin means, not too surprisingly, twice a day. The abbreviation
b.i.d. is sometimes written without a period either in lower-case
letters as "bid" or in capital letters as "BID". However it is
written, it is one of a number of hallowed abbreviations of Latin
terms that have been traditionally used in prescriptions to specify
the frequency with which medicines should be taken. Other examples
- q.d. (qd or QD) is once a day; q.d. stands for "quaque
die" (which means, in Latin, once a day).
- t.i.d. (or tid or TID) is three times a day ; t.i.d.
stands for "ter in die" (in Latin, 3 times a day).
- q.i.d. (or qid or QID) is four times a day; q.i.d.
stands for "quater in die" (in Latin, 4 times a day).
- q_h: If a medicine is to be taken every so-many hours, it is
"q_h"; the "q" standing for "quaque" and the "h" indicating the
number of hours. So, for example, "2 caps q4h" means "Take 2 capsules
every 4 hours."