PRESCRIPTION WRITING 73 



Yet one should -always lean to simplicity rather than complexity in the 

 number of ingredients. While it is difficult to avoid chemical antagonism, 

 how much harder is it to prevent untoward physiological combinations in 

 the body, which we can in no wise foretell. In olden times ignorance 

 led practitioners to try the effect of an enormous number of drugs, with 

 the hope that out of the charge one at least of the pellets in these shot- 

 gun prescriptions might strike the desired spot, if the others failed to do 

 so. But we now believe that the damage done by all the shot which miss 

 far surpasses the good accomplished by the successful missile. Four 

 hundred different remedies are included in one of these old formulae, 

 whereas now it is rare to find four in a prescription. 



In relation to the third part of the prescription (the directions to 

 the compounder), we find that a few regulation Latin phrases or words 

 express these directions. If one is unfamiliar with Latin, one can easily 

 memorize these words and phrases understandingly. The directions to 

 the attendant are heralded by the Latin signa, or signetur, meaning label, 

 or let it be labelled; abbreviated, "Sig." or merely "S.," and being for 

 the use of the attendant of the patient, are in English. The directions 

 should be very precise. One should not write: "Use as directed," or 

 "Give in water," but indicate exactly the quantity of medicine to be 

 administered, the precise amount of water with which it is to be diluted, 

 and the time at which it is to be given. For instance: "Give one table- 

 spoonful in half a pint of water three times daily after feeding." 



Poisons should be marked as such. It is well sometimes to indicate 

 that the prescription is "for a horse," in order to avoid mistakes and to 

 quell the qualms of the conscientious druggist. 



Preparations which are not to be used internally should be labelled 

 "external use." Under "signature" the name of the writer and date is 

 included. If desirable, one may inscribe "non repetatur," do not repeat. 

 Quantities used in prescription writing are indicated by the signs of the 

 apothecaries or troy system of weights for solids. For liquids, signs 

 representing units of the wine measure are employed. The troy grain 

 and ounce are used by apothecaries as units of weights in dispensing 

 prescriptions. In ordering large quantities (-as pounds) the avoirdupois 

 pound of 16 ounces is employed, and in buying ounces of drugs without a 

 prescription the avoirdupois ounce is also utilized. The avoirdupois ounce 

 contains 437 grains ; the troy ounce contains 480 grains. The grain is 

 of similar value in both systems. 



Troy or Apothecaries' Weight. 



Weight Sign Latin Name 



Pound ib Libra 



Ounce — ,^ Uncia 



Dram 3 Drachma 



Scruple 9 Scrupulum 



Grain gr. Granum 



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