50 GENERAL ACTION OF DRUGS 



(b) Antigalactagogues. — Belladonna is the only efficient drug less- 

 ening the secretion of milkj applied locally or given internally. It 

 paralyzes the peripheral secretory nerve-endings and is useful in mam- 

 mitis by diminishing the circulatory activity in the mammary gland. 



DRUGS INFLUENCING METABOLISM. 



(1) Alteratives. — The term "alterative" is a vague, indefinable 

 word used to describe the action of certain drugs modifying tissue change 

 and improving nutrition in some disorders. The word is simply a cloak 

 for ignorance and should be dropped. The value of alteratives has been 

 discovered by clinical experience. The following are often classed as 

 alteratives : 



Arsenic and its preparations Phosphoric acid 



Mercury and its salts Colchicum 



Iodine and its salts Sarsaparilla 



Cod liver oil Sulphur 



Uses. — Alteratives are employed in those diseases in which experi- 

 ence has proved them to be beneficial. 



Tonics. — The word "tonic" is another term even more vague and 

 all-embracing than "alterative," and, therefore, impossible to define pre- 

 cisely. Tonics improve the general nutrition and health, and, as ordi- 

 narily understood, refer to drugs promoting appetite and digestion (bitter 

 tonics, as gentian) ; the state of the blood (hematinics, as iron and 

 arsenic); or the condition of certain organs (heart tonics, as digitalis; 

 nervines, as strychnine). Strychnine is the best example of a tonic. 

 "Tone" is largely due to reflex activity (response to stimulation) which 

 is preeminently stimulated by strychnine. 



Tonics are indicated in the treatment of debility (general or special) 

 and anemia. 



DRUGS INFLUENCING BODILY HEAT. 



Antipyretics are drugs lowering the temperature of the body in 

 fever. The mechanism concerned with temperature changes is' as follows : 



1. Heat Production. There are centres for heat-production at the 

 base of the brain (tuber cinereum and corpus striatum), and less im- 

 portant heat-producing centres in the upper part of the spinal cord. 



2. Heat Loss. There are centres for heat loss in the cerebrum 

 (cruciate and sylvian), and also at the base, in the tuber cinereum, in- 

 creasing the frequency of respiration. Then the vasomotor and respira- 

 tory centres in the medulla and the sweat centres (probably also situated 

 in the medulla) all contribute to heat loss. This follows from the loss 

 of heat through evaporation of sweat, by the dilatation of the superficial 

 vessels in the absence of sweating, and through the more rapid exchange 

 of air caused by increased frequency of respiratory movements. Heat is 

 also lost in the passage of urine and feces. 



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