Parathyreoidin

PARATHYREOIDIN (Parathyreoidin), a general name for preparations made from the parathyroid glands (glandulae parathyreoideae). For a long time, the production of these preparations was carried out without regard for their specific activity due to the lack of appropriate research methods. In most cases, Parathyreoidin or similar preparations under other names were prepared according to the type of ordinary dry organotherapeutic preparations, which are dried, ground, defatted, and dehydrated glands. Only in 1925 did Collip provide a formula for obtaining a preparation from the parathyroid glands, the specific activity of which was confirmed by the elimination, with its help, of the phenomena of tetany that occur following the removal of these glands. As a reference point in the course of his research, Collip focused on the influence of the extracts he obtained on the Ca content in blood serum. The amount of the latter in a normal human and most laboratory animals is 10-12 mg per 100 cm³ of blood serum. After extirpation of the glands in dogs, the Ca content in the serum drops to 6-7 mg per 100 cm³. The extract, which proved capable of equalizing the Ca content in the blood of parathyreoprivic dogs, at the same time provided complete elimination of all symptoms of parathyreoprivic tetany. The preparation, according to Collip, is prepared in the following way: extraction of the glands with 3-5% hydrochloric acid while heating, removal of fat, treatment of the extract with alkali in the cold, precipitation of ballast protein substances in the cold by their coagulation in a weakly acidic medium (pH=5.5) and their removal; saturation of the filtered and strongly acidified with hydrochloric acid extract with table salt leads to the salting out of the active principles, which float to the surface; the floated substances are collected and, after dissolution in a weak acid, are additionally purified by repeated precipitation at the isoelectric point (pH=4.8). The protein fraction isolated in this way is a preparation that, for clinical use, is dissolved in weak hydrochloric acid and preserved with antiseptics or passed through a Berkefeld filter. The preparation is quite stable with respect to acids, alkalis, and temperature, but is destroyed by treatment with pepsin and trypsin. The activity of the solutions is established by biological standardization on dogs. 1 unit of action (U) is taken as 1/100 of the amount capable, upon simultaneous subcutaneous injection into healthy dogs (weighing about 20 kg) that have fasted for 18-24 hours, of causing an increase in the serum Ca content of 5 mg per 100 cm³ 15-18 hours after injection. The preparation is used primarily in cases of functional insufficiency of the parathyroid glands (e.g., in spasmophilia of early childhood, hypertonic states of the muscular system, disorders after removal of the thyroid gland, etc.), often in combination with Ca salts. In addition, success is noted in a number of diseases accompanied by a decrease in the Ca content in the serum; such are some cases of ulcerative processes on the gastric mucosa, some forms of bronchial asthma and whooping cough, lead poisoning, and aphthae tropicae (sprue). The preparation is administered subcutaneously in doses of 20 to 100 U. Commercial preparations usually contain 20 U in 1.0 cm³. The most well-known is the American preparation Parathormone. In the USSR, a similar product is produced by the Institute of Experimental Endocrinology of the People's Commissariat of Health in Moscow under the name parathyreocrin.