682 ADRENALIN 



and keeps well in weak acidulated solution, but neutral 

 solutions slowly undergo alteration. Adrenalin chloride 

 solution (1 : 1000), containing one part adrenalin chloride and 

 five parts chloretone in a thousand parts of normal salt 

 solution, is generally used in veterinary practice. This 

 preparation should be kept in well-stoppered bottles, in a 

 cool, dry place, as exposure to air and light, by inducing 

 oxidation, gradually destroys its value. 



ACTIONS AND USES. Solution of adrenalin chloride has 

 little or no action on the unbroken skin. When applied 

 to abraded surfaces or mucous membranes, or when injected 

 subcutaneously, it causes local constriction of the arterioles 

 and capillaries, with the result that the part becomes pale 

 and bloodless. 



Internally, when injected intravenously, even in minute 

 doses, it causes a general constriction of the smaller blood- 

 vessels throughout the body, with the exception of those 

 of the lungs and brain. This action is believed to be due 

 partly to the excitation of the sympathetic nerves of the 

 part, and partly to direct action on the muscle fibres in the 

 walls of the vessels. Adrenalin also slows and strengthens 

 the heart's action, and causes an extremely rapid rise of 

 blood-pressure, much in the same way as does digitalis. 

 This rise of blood-pressure is chiefly due to the action of 

 the drug in stimulating the sympathetic vaso-constrictor 

 nerves, in constricting the muscular coats of the peripheral 

 arterioles, and to its tonic effects on the heart muscle, 

 strengthening the systole. A very small amount injected 

 intravenously will increase the blood-pressure immediately, 

 but its action is very transient, and the dose requires to 

 be repeated at short intervals. On the other hand, little 

 or no systemic effect is to be expected from its administra- 

 tion orally or per rectum, as it becomes quickly oxidised 

 in the tissues. Besides its effects on the circulatory appar- 

 atus, adrenalin affects several other forms of involuntary 

 (unstriated) muscle. Thus, intestinal and stomach move- 

 ments are inhibited, whilst the ureters, vesiculse seminales, 

 uterus and vagina all show contractions. Again, the pupil 

 of the eye is dilated, the membrana nictitans is retracted, 

 and the eyeball protruded. All these effects can be ob- 



