453 DRUGS OF ANIMAL ORI.GIN 



posity with dwarfism or acromegaly. Disease of the pituitary with that of other 

 glands, as the genitals, leads to enuchoidism, etc. 



Do«e.— Mares and Cows, 3i-iii, (4-12) ; Sows and Ewes, Tn.45, (3) ; Bitches, 

 Tll,xv, (1), as oxytocic. 



Actions. — Pituitrin somewhat resembles adrenalin in its effect upon 

 the body. The mechanism by which this effect is produced is different 

 in the case of the two agents. When injected intravenously pituitrin 

 causes a rise of blood pressure, which is rather less than that obtained 

 with adrenalin, but lasts longer (6 to 30 or even 60 minutes). The 

 heart's action is also slowed but not increased in strength. Experiments 

 show that pituitrin stimulates directly smooth muscle and this explains 

 its action on vessel walls, and also accounts for its influence in stimulating 

 intestinal peristalsis and uterine contractions of the pregnant organ. 

 Another important distinction between these glandular products: While 

 adrenalin fails to constrict the arteries of the lungs, brain and heart, 

 because of the absence of sympathetic constrictor fibres in the vessels of 

 these organs, pituitrin causes contraction of the pulmonary, cerebral and 

 coronary arteries by stimulating the muscular coat of these vessels. 



The arterioles of the spleen and kidney are dilated, and diuresis 

 follows the action of pituitrin from increased blood pressure. Pituitary 

 extract apparently increases the flow of milk and fat but only empties 

 out all the secretion by stimulation of smooth muscle. It lessens polyuria 

 in diabetes insipidus. It has no action on the non-pregnant womb. 

 Like adrenalin, the action of pituitrin is most marked after intravenous, 

 subcutaneous and intramuscular injection, arid is practically nil when the 

 extract is given by the mouth. Pituitary extract inhibits to a certain 

 extent the secretion of the thyroid, in hyperthyroidism, and also that of 

 the pancreas. Pituitrin is not especially toxic, since neither IS mils of the 

 extract by the mouth, nor 3 mils hypodermically, caused any poisonous 

 symptoms in 400 Gm. guinea pigs (Houghton). 



To summarize: Pituitrin (posterior lobe) stimulates smooth muscle 

 and hence the heart, vessel walls, uterus and intestines ; it increases cer- 

 tain secretion, as the urine; and causes contraction of the arterioles of 

 the lungs, brain and heart ; and increases carbohydrate metabolism. The 

 anterior part of the gland increases oxidation, stimulates growth of 

 skeletal and connective tissue, and aids development of the sexual organs. 



Uses. — The uses of pituitrin hang directly upon its known physio- 

 logical action. Thus it is given intravenously to constrict blood vessels 

 in shock. While its action is less powerful and sudden, its influence is 

 more permanent, than that of adrenalin. 



It has been largely employed to stimulate rhythmic contractions of 

 the parturient (human) uterus in inertia. Unless the os is fully dilated 

 the contractions produced by pituitrin are occasionally so violent as to 

 cause rupture of the uterus — ^which has occurred in several reported 

 cases, but it is a valuable drug in uterine inertia in bitches, cats and 

 sows. In tympanites — especially that due to atony of the intestines fol- 

 lowing surgical operations — pituitrin is sometimes immediately successful. 

 In flatulent colic of the horse pituitrin is worthy of trial. It appears to 

 be the most certain agency for rapidly evacuating the bowels in human 



Digitized by Microsoft® 



