20 MATER r A ME DIG A AND THERAPEUTICS. 



intended to be the rational result of as accurate a 

 knowledge as can be gained of the disease which has 

 to be remedied, and of the means at our command of 

 doing so. How this choice is to be made will be 

 discussed under General Therapeutics in the third 

 part of the work. 



Idiosyncrasy. Before finally deciding, however, 

 on certain drugs, idiosyncracy must not be forgotten ; 

 that is, the peculiar susceptibility of some individuals 

 to the action of particular medicines, such as opium, 

 mercury, quinine, essential oils, and ipecacuanha. In 

 almost every instance such idiosyncrasy means in- 

 creased susceptibility ; unpleasant or even dangerous 

 results following an ordinary or even minute dose. 

 It is well, therefore, before ordering such drugs, to 

 enquire whether the patient has taken them pre- 

 viously, and if not, to use them cautiously at first. 



2. Selection of the preparation. The drug 

 having been selected, the particular preparation of it 

 will be selected in accordance with the considerations 

 discussed under the head of varieties of preparations. 

 The Pharmacopoeia affords abundant choice, according 

 to the channel by which it is to be administered. 

 This naturally leads us to consider the 



MODES OF ADMINISTRATION OF DRUGS. 



(a) By the skin, or mucous membrane continuous 

 with the skin, whether simply applied or rubbed in (lini- 

 ment, ointment) ; painted on (pigment) ; worn on the 

 skin (as a plaster) ; applied in a state of fine division 

 by fumigation, with or without sweating ; used as a 

 gargle, injection, or wash ; or insufflated on to a part. 

 The effect desired is usually local only, but it may be 

 general, many drugs being absorbed by the skin. 



(6) By the mouth, to act locally on the alimentary 

 canal, and to be absorbed from it, especially from the 

 stomach. 



