In the following pages are given some problems and exercises such as are met every day in the practice of medicine. No attempt is made to cover the entire field, but it is hoped that enough and' sufficient variety is given to be of advantage in the study of materia medica and prescription writing. They are also so arranged as to amount to a quiz on many important points in posology, toxicology, metrology and other phases of the subjects. The author begs to acknowledge his rather remote acquaintance with arithmetic, and the discussions, from this standpoint, may seem rather crude and void of system to better scholars, but the effort was made to illustrate different methods of reasoning out the desired results, and the reader can make his choice or be led to improve on any of the lines suggested. In teaching medical students, the urgent need of exercises of this character has been thoroughly demonstrated.

The common preparations of opium,-tincture of opium, tincture of deodorized opium, camphorated tincture of opium and powder of ipecac and opium,-are made from the powdered or granulated opium, which now contains about 10 per cent. of morphine. In giving opium, or its preparations, a smaller dose is employed than the morphine content would indicate, for it must be remembered that there are other active ingredients, particularly codeine.

(1) How much opium; how much morphine, in:

(a) 5 drops of laudanum?

(b) 10 drops of paregoric?

(c) 5 grains Dover's powder?

Discussion.

(a) Laudanum, as most other tinctures, gives about 2 drops to the minim-usually a little more than 2 drops. One minim of laudanum represents about 0.1 (Mo) grain of opium, or 0.01 (Moo) grain of morphine. Five drops, which would be a little more than 2 minims, would represent a little more than 1/5 grain of opium and 1/50 grain of morphine.

(b) Paregoric represents 0.4 per cent. of opium, or about 0.04 per cent. of morphine. One minim would, therefore, represent about 0.004 grain opium, or 0.0004 grain morphine. Ten drops would be about 4 minims, and would represent about 0.016 (1/60) grain opium, or 0.0016 (1/600) grain morphine, or

Paregoric represents 4 parts of opium to 1000, or 1 to 250; 1 minim would, therefore, represent 1/250 of a grain, and 4 minims would represent 4/250 (1/60) of a grain; 1/10 of this (1/600) would be morphine.

(c) Dover's powders contain 10 per cent. of opium, so 10 grains would contain 1 grain of opium, or 5 grains would contain 1/2 grain of opium; 1/10 of this would be morphine- 1/10 of 1/2 is 1/20 (grain of morphine).

(2) How much morphine in:

(a) 2 grains powdered opium?

(b) 1/2 grain extract of opium?

Discussion.

(a) Powdered opium contains about 10 per cent. of morphine, so Mo of it is morphine. If 1 grain of opium contains Mo grain of morphine, 2 grains contain 2/10 (1/5) grain morphine.

(b) Extract of opium contains about 20 per cent. of morphine-20 per cent. of 1 grain would be 1/5 grain; 20 per cent. of 1/2 grain would be 1/10 grain; or-20 per cent. is 20 to the 100-100 grains of the extract contain 20 grains of morphine, so 1 grain of the extract contains 1/5 grain of morphine and 1/2 grain of the extract contains 1/2 that much, or Mo grain.

(3) A man phones that his wife has swallowed a tablespoonful of laudanum.

(a) How much opium did the patient get?

(b) How much morphine?

(c) Relation of amount to average dose?

Discussion,

(a) A tablespoonful is about 4 fluidrachms or 240 minims. If laudanum represents 10 per cent; of opium, 240 minims of the tincture would represent 24 grains of the drug.

(b) If opium contains 10 per cent. of morphine, 24 grains of opium contains 1/10 as much, or 2.4 (24/10) grains of the alkaloid.

(c) As the dose of opium is 1 grain and morphine 1/8 grain, this patient received over twenty times the average dose.

(4) A lady phoned that a child 2 years old had been given a tea-spoonful of paregoric by mistake, and what should she do till medical attention arrived?

(a) How much opium had the child received?

(b) How much morphine?

(c) Relation of morphine received to an average dose for a child that age?

Discussion.

(a) Paregoric contains 4 parts of opium to the 1000; therefore, 1 minim contains 1/250 grain of opium; 60 minims (1 teaspoonful) contains sixty times as much, or 60/250, or about 1/4 grain opium.

(b) As opium contains about 10 per cent. of morphine, 1 grain opium contains 1/10 grain morphine, and 1/4 grain opium contains 1/40 grain of the alkaloid.

(c) A child 2 years old would usually receive 1/7 of the adult dose (Young's rule). If the dose of morphine is 1/8 grain, this child would take 1/7 as much, or 1/7 of 1/8 = 1/56. So the morphine received is to the average dose as 1/40 is to 1/56, or about 1/3 more than the average. It should be remembered that opium contains other active agents, so the child received equal to about twice an average dose of morphine, but hardly a toxic quantity.

(5) Through error the tincture of deodorized opium was ordered in place of paregoric in what was intended to be this prescription:

(Adult)

Date,

M.

Sig

Tablespoonful every four hours. (Shake-label.)

How much opium per dose did patient get? How much morphine? Relation to average dose?

Discussion.

As the tincture of deodorized opium represents 10 per cent. of the drug, 3 fluidrachms (180 minims) would represent about 18 grains of opium, or about 1.8 grains morphine.

Three fluidounces contain 6 tablespoonfuls, so the patient would receive in each dose about 3 grains opium or about 0.3 ( 1/3) grain morphine.

This would be about three times the average dose, but hardly a toxic quantity under ordinary circumstances, unless repeated.

(6) Write a prescription for suppositories that will contain a sufficient amount of some preparation of opium to give about 15 mg. of morphine to each suppository.