Glycerin

GLYCERIN (Ph. VII), Glycerinum, CH₂OH.CHOH.CH₂OH, a trihydric alcohol, trioxipropane, propanetriol. Obtained from the decomposition of fats and fatty oils, which are glycerides, i.e., complex esters of glycerin and fatty acids. G. is a colorless, odorless, sweet-tasting, syrupy liquid of neutral reaction, specific gravity 1.225-1.235; dissolves in all proportions in water and alcohol, almost insoluble in ether, carbon disulfide, chloroform, fatty and essential oils, gasoline; highly hygroscopic. The German Pharmacopoeia permits commercial G. to contain 13-16% water. According to requirements Ph. VII, a 1:5 solution of G. should not give reactions to salts of Ca, Fe and other heavy metals, salts of sulfuric acid, or As; should not give a precipitate with a solution of calcium chloride (oxalic acid). G. should not contain acrolein, grape sugar and other reducing substances, ammonium salts, fatty acids. When G. is burned in a porcelain crucible, after calcining the crucible, no weighable residue should remain. The local action of G. on tissues is due to its ability to absorb water, which causes dehydration of tissues and thereby their irritation. The same is observed with intact skin when G. is applied per se. On abrasions (places devoid of epithelium), even diluted G. has a significant irritating effect, but this effect soon passes, and G. as an coating protects damaged tissues from external influences. G. also has a softening effect on the skin and the crusts formed on its surface. In high concentrations, G. possesses antiseptic properties, due to which it is used as a preserving medium (e.g., for brain preparations, muscle preparations, internal organs, as well as some medicinal substances). On mucous membranes, G. has a noticeable irritating effect, although when taken per os it is tolerated in large doses (over 100.0), sometimes with diarrhea observed. A significant portion of G., introduced per os, after absorption is synthesized with fatty acids into fats; the remainder is burned, and only a small amount of G. is excreted unchanged by the kidneys. When administered subcutaneously or intravenously, G. is already highly toxic and causes death in an animal at a dose of 9.0 per kg of body weight. At this, dissolution of red blood cells is observed (which is associated with G. removing water), hemoglobinuria, methemoglobinuria, infarcts in the kidneys. Additionally, animals first show signs of excitement, rapid pulse, accelerated respiration, increased temperature, trembling and convulsions, and then weakness, drowsiness and coma. The cause of death is paralysis of respiration. Introduction of G. into the rectum causes even in small doses irritation of the rectal mucosa, accompanied by increased peristalsis and diarrhea. G. is used externally per se or, to avoid irritation, with water (30-50% water), also with alcohol and in the form of ointments, often with vaseline and lanolin for softening the skin, with cracks on the lips, hands, etc.; internally - for trichinosis with tablespoons up to 150.0 pro die to cause paralysis in intestinal trichinae. Also in large doses (50.0-150.0) with water for urinary stones, the excretion of which supposedly in case of their small size occurs more easily and less painfully after taking glycerin; this effect, however, is denied by many authors (e.g. Cushny). In the form of small enemas of several cubic cm per enema and suppositories consisting of 35% G. and containing 1.0-2.0 G. in each suppository - for constipation. Prolonged use of G. is irrational, as the excitability of the mucosa gradually decreases and the effect disappears. To enhance uterine contractions, G. is introduced into the cervical canal. When large amounts of G. are introduced into the uterus, general poisoning is possible, similar to that observed when G. is introduced into the blood; G. is used as a solvent for various medicinal substances (extracts, alkaloids, tannin, phenol, water-soluble metallic salts), especially those used externally, for example a 10-15% solution of Ac. carbolici in anhydrous G. (ear drops). In such use, the therapeutic properties of G. itself are also important, mainly coating, which ensures protection of tissues and better adhesion of the drug to mucous membranes and skin when they are smeared, e.g. when using boric G.-Glycerinum boricum. Glyceritum Ac. tannici (amer.): Ac. tannici 20.0, Glycerini 80.0. G. lacto-carbolicum: a mixture of G., lactic acid and phenol. Used for smearing the larynx in its tbc, with a sequential increase in the concentration of carbolic and lactic acids: i

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