Discussion.

Ferrous carbonate is on the market only in the form of its preparations. The mass is used for capsules, and contains about 35 per cent. of the salt, so 6 grains would be required for each capsule. The average dose of strychnine sulphate is 1/40 grain, of arsenic trioxide is 1/30 grain; 60 doses would require sixty times these amounts, or

60x1/40 or 60/40 equals 1 1/2 grains strych. sulphate.

60x1/30 or 60/30 equals 2 grains arsenic trioxide.

60x6 or 360 grains mass of ferrous carbonate.

Using the rule for transposing (see p. 336) we would have about as follows:

Name of patient, etc.

Date,

Appendix Problems And Blackboard Exercises Part 4 1537

Strychninae Sulph............

100

Arseni Trioxidi.............

130

Mas. Ferri Carb.................

24

000

M. ft. cap. no. lx.

Sig

One after each meal

Signature.

(22) How much actual ferrous iodide in the U. S. P. average dose of the syrup ?

Discussion.

As the syrup contains 5 per cent. of the salt, 1 minim contains about 1/20 of a grain; 15 minims (the average dose) contains 15/20 or 3/4 grain.

(23) A common vehicle is chloroform water in tablespoonful doses. How much chloroform to each dose?

Discussion.

As chloroform is soluble in about 200 parts of water and the official chloroform water is a saturated solution, 200 minims of the water would contain 1 minim of chloroform, 240 minims (1 tablespoonful) would contain 240/200 or 1 1/5 minims of chloroform.

(24) In treating certain gastro-intestinal pains, the spirit of chloroform is recommended in 1/2 teaspoonful doses. How much chloroform to each dose?

Discussion.

As the spirit of chloroform is a 6 per cent. solution, and a half tea-spoonful is 30 minims, the answer is obtained by finding 6 per cent. of 30. 30x0.06=1.80 (minims of chloroform).

(25) A doctor orders a spray of 2 fluidrachms of the solution of hydrogen dioxide to each 6 fluidrachms of water (each fluid-ounce of the finished prescription). What percentage of H2O2 in the preparation, and how many volumes of available oxygen?

Discussion.

Two fluidrachms to the fluidounce gives a 25 per cent. solution. The official preparations contain 3 per cent. of H2O2, so the prescription would contain 25 per cent. of 3 per cent., or 0.25 x 0.03 equals 0.0075 or 0.75 per cent. The official preparation contains 10 volumes of available oxygen. If the prescription contains 25 per cent. of the solution, it would contain 25 per cent. of as many volumes of oxygen-25 per cent. of 10 = 0.25 x 10 = 2.50 (2 1/2 volumes of available oxygen).

(26) How much ether in a teaspoonful of Hoffmann's anodyne?

Discussion,

As the preparation contains 32.5 per cent. of ether, 60 minims (1 teaspoonful) would contain 32.5 per cent., of 60 minims of ether-0.325 x 60 = 19.500 (minims of ether).

The approximate amount may be found as follows:

As the spirit is about 1/3 ether and a teaspoonful is about 60 minims, 1/3 of 60 is 20 (minims of ether).

(27) How much tartar emetic in 2 teaspoonfuls of the compound syrup of squills?

Discussion.

As the preparation contains 0.2 per cent. of the salt, and 2 teaspoonfuls is 120 minims it would contain 0.2 per cent. of 120, or 120 x 0.002 = 0.240 (or about 1/4 grain).

(28) Through error a patient swallowed a teaspoonful of a mixture of equal parts of tinctures of iodine and aconite. How much actual iodine did the patient get?

Discussion.

As the tincture of .iodine is a 7 per cent. solution, and a teaspoonful (60 minims) of the preparation was taken, and it was half tincture of iodine, the patient received 30 minims of tincture of iodine containing about 7 grains to each 100 minims-7 per cent. of 30 = 30x0.07 = 2.10 (grains of iodine).

(29) Write a prescription calling for 2 ounces of an ointment containing 1 per cent. phenol and 5 per cent. zinc oxide-use the ointment of zinc oxide instead of the salt.

Discussion.

An ounce by weight is 480 grains (apothecaries), so the amount of phenol to make 1 per cent. in 1 ounce is 1 per cent. of 480 or 4.8 grains. Five per cent. would be five times that much, or 5x4.8 or 24 grains. For a 2 ounce ointment, twice as much would be required, or 9.6 grains phenol and 48 grains zinc oxide. Zinc oxide is hard to properly incorporate, so the U. S. P. 20 per cent. ointment should be employed. If the ointment contains 20 per cent. of the salt, each 5 parts of the ointment contains 1 part of the salt. If 48 grains of the salt is required, five times that much of the prepared ointment would be nece'ssary-48x5 or 240 grains, or 4 drachms.

Name, etc.

Date,

Appendix Problems And Blackboard Exercises Part 4 1538

Phenolis...........

gr. x

Ung. Zinci Ox..........

3iv

Petrolati................

q. s.Appendix Problems And Blackboard Exercises Part 4 1539

M.

Sig

Apply as directed.

(Over)

Signature.

Directions may be given on back of prescription to melt the phenol and petrolatum and incorporate while hot, or the necessary amount of the U. S. P. phenol ointment may be ordered.

(30) Write a prescription for an office solution containing about 1 per cent. cocaine and 3 per cent. of antipyrine.

Discussion.

A fluidounce of water weighs about 450 grains, so the amount of a salt required to make a 1 per cent. solution in 1 fluidounce is 1 per cent. of 450 or 4.5 grains. Three per cent. would require three times 4.5 or 13.5 grains. Approximate quantities are usually employed. As the solution does not keep well, a small quantity is usually ordered.

Heading showing address, registry number, etc.

Name. etc.

Date,

Appendix Problems And Blackboard Exercises Part 4 1540

Cocainae Hydrochl.........

gr. v

Antipyrinae.............

gr. xv

Aquae Dest,................

q. s.Appendix Problems And Blackboard Exercises Part 4 1541

M.

Sig

Formula.

Signature.

(31) A physician wished a patient to use a 1 to 500 quinine solution to irrigate the colon in the treatment for pinworms. Write the prescription necessary.

Discussion.

Quinine alkaloid, sulphate or tannate would not dissolve in this strength. The hydrochloride would answer well. One grain to the fluidounce makes a little more than a 1 to 500 solution, so about 15 grains to the pint, or 60 grains to the half gallon, would be required.