OFFICIAL PREPARATIONS ..^ 63 



Pharmaceutical Preparations. 



The "United States Pharmacopeia" is an authoritative bookj includ- 

 ing the drugs in most common use, with a description of their properties, 

 tests for their purity, and methods for making their preparations. It is 

 revised each decade by a convention of representative delegates from 

 medical schools and societies, schools of pharmacy and pharmaceutical 

 associations, with the collaboration of medical officers of the army, navy 

 and public health service. The last edition dates from September 1, 

 1916. All matter occurring in the "Pharmacopeia" is said to be accord- 

 ing to the U. S. P., or official. That occurring in the "British Pharma- 

 coJ)eia" is marked B. P. The dispensatories in the United States are 

 three: The United States, National and Kings, which contain all matter 

 in the Pharmacopeia and much besides pertaining to materia medica and 

 therapeutics. The National Formulary is published by the American 

 Pharmaceutical Society and contains important formulae not included in 

 the U. S. Pharmacopeia. 



OfRcial Preparations. ■ 



I. — Preparations Whose Solvent Is Water. 



Decqctum, pi. decocta. — Decoctions are solutions of crude drugs in 

 water, obtained by boiling. Unless specified otherwise, their strength is 

 5 per cent., and the boiling is conducted fifteen minutes. Decoctions 

 tend to undergo rapid decomposition, and are suitable only in case of 

 those drugs whose active principle is soluble in water. They are unsuit- 

 able when the active principle of a drug is volatile, decomposed by heat, 

 or when it contains much starch, which would form an easily decompos- 

 able, thick mass. 



Drugs containing hard, woody substances, especially albumin, which 

 coagulates in boiling and remains in the crude drug, are those especially 

 adapted for this method. 



Infusum, pi. infusa. — Infusions are aqueous solutions of drugs made 

 by maceration in cold or boiling water, without the aid of ebullition. 

 Maceration is done for half an hour, and the strength is 5 per cent., 

 unless otherwise ordered. The same disadvantages apply in the case of 

 infusions as with decoctions, in addition to the longer time . required for 

 their preparation. Some drugs, as digitalis or ergot, which yield their 

 active principles to water and are more powerful when freshly made, are 

 suitable for this process. 



Liquor, pi. liquor es. — Solutions are preparations holding active non- 

 volatile principles in solution in water. They have no uniform strength. 



Aqua, pi. aquae. — Waters are aqueous solutions of volatile principles. 

 They have no uniform strength and are mostly solutions of volatile oils 

 or gases. 



Mistura, pi. misturae. — Mixtures are compounds consisting of a com- 

 bination of fluid preparations or compounds in which solid substances 

 are dissolved or held in suspension by an appropriate vehicle. The term 

 is thus very comprehensive, including most prescriptions for fluids used 



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