This section is from the book "Materia Medica: Pharmacology: Therapeutics Prescription Writing For Students and Practitioners", by Walter A. Bastedo. Also available from Amazon: Materia Medica: Pharmacology: Therapeutics: Prescription Writing for Students and Practitioners.
When there can be no possible mistake in meaning, abbreviations are allowable as follows:
I. Of Ingredients. - (a) In the name of the class of preparations, as elix., tinct., syr., pil., suppos., ungt. (or ung.). The abbreviation Tr. should not be employed for tincture, as in script form it has frequently been incorrectly read Fe i. e., fluidextract.
(b) In modifying adjectives, as esq. for aequalis, comp. for compositus, ppt. for praecipitatus, recent. for recentis, sat. for saturatus.
(c) In amounts - q. s. for quantum sufficiat (as much as may be required), āā for ana (of each), and the regular symbols of weights and measures.
(d) In prepositions - c for cum, s for sine.
II. In the Directions for Compounding. - (a) In nouns and adjectives, as each., chart., pil., suppos., tab., tab. trit., tab. hyp., troch., scat. (scatulam = a box), dos. tal. (doses tales = such doses).
To express the kind of coating for pills write argent, (argenti-ferus) = silver-coated, sacchar. (sacchariferus) = sugar-coated, and gelat. (gelatiniferus), or g. c. = gelatin-coated, after the term for pill. The terms "keratin-coated"- and "salol-coated" are best written in English. To order that powders should be put in waxed papers, write for chart. cerat. (chartas ceratas). Such are used for efflorescent or deliquescent drugs, and for the latter especially if the patient is to be at the seashore or aboard ship.
(b) In verbs - ft. for fiat or fiant (let it or them be made), div. for divide (divide), M. for misce (mix), S. or Sig. for Signa (label), bull. for bulliat or bulliant (let it or them boil).
An example of the use of these abbreviations might be: Ft. pil. argent. No. xij (Fiant pilula argentifera, numero duodecim) = let twelve silver-coated pills be made.
III. In the Directions for the Label. - (a) Relating to quantity - gtt. (drop), 3j (one teaspoonful), 3ij (one dessertspoonful), 3iv (one tablespoonful), cochl. parv., coch. mag. (cochlearia parva, magna = small or large spoon). The term cochlearia might properly be abandoned.
(b) Relating to the time of taking - h. (hour), min. (minute); stat. (statim = at once); a. c. (ante cibum = before eating), p. c. (post cibum = after eating); q. h., q. 2 h., q. 3 h., q. 4 h. (quaqua hora = every hour, every two hours, etc.); o. d., b. i. d., t. i. d., 4 i. d. (omne die, bis in die, ter in die = daily, twice a day, three times a day, etc.); o. m., o. n. (omne mane = each morning, omne nocte = each night); M. et N. (mane et nocte = morning and night; also written "mane nocteque," and "a. m. et p. m."); s. o. s., p. r. n. (si opus sit = if there is necessity; pro re nata = when required). In some circles a distinction is made, s. 0. s. referring to one dose only, and p. r. n. to any number, its interpretation being, "whenever needed."
(c) In aq. (in aqua = in water).
An example of the use of such directions would be:
Sig:- 3j in aq. t. i. d. 10 min. a. c. = a teaspoonful in water three times a day, ten minutes before meals.
Though it would certainly be the safest plan to write directions for the label in full English, it is not the custom to do so.
IV. Special abbreviations, usually placed at the top of the prescription blanks, are P.P. = poor patient, and ne rep. - ne repetatur (not to be repeated).
Observe that the proper abbreviation for drops is gtt. and not gtts., for grains is gr., for grams is gm., and for pill or pills is pil. not pill.