Oleum Morrhuae

Cod-liver Oil

Cod-liver oil. Huile de morue, Fr.; Leber-thran, Ger. A fixed oil obtained from the fresh livers of Gadus mor-rhua, or of other species of Gadus.

Composition

Cod-liver oil contains a peculiar principle, gaduin, and yields, by distillation with ammonia, propylamin. It also differs from the fats and oils above described in containing various biliary principles and traces of iodine, bromine, phosphorus, sulphuric and phosphoric acids, lime, magnesia, soda, and iron. It agrees with the other oils in being composed for the most part of olein and margarin. It is the latter constituent which gives the white cloudiness of cod-liver oil in cold weather, and which is, by the "British Pharmacopoeia," directed to be separated by artificial cooling. According to Winkler, cod-liver oil does not yield glycerin, but oxide of propyl, when saponified. There are three varieties of oil, due, not to differences in composition, but to modes of preparation: the pale, the light-brown, and the dark oil. The pale oil is freest from the products of decomposition and empyreuma, is the best for internal administration, and is the official preparation.

In order to obtain more positive therapeutical results, certain medicinal substances are frequently added artificially to the cod-liver oils of commerce. Iodine, bromine, phosphorus, and iron, are thus added. Not only are such compounds bad, chemically considered, but the addition of such ingredients gives great opportunities for sophistication, and impure brown and other fish-oils may be substituted for the pure cod-liver oil. Besides, these combinations possess no therapeutical advantage.

It has been supposed that any oil or fat, even glycerin, may be used in place of cod-liver oil, and cream has been prescribed in this belief. Linseed-oil has been considered to have some special efficacy in wasting diseases, more particularly in phthisis, because of the large amount of vegetable albumen which it contains. These notions are erroneous. Cod-liver oil has special therapeutical virtues because it contains gaduin, propylamin, the constituents of bile, iodine, phosphorus, bromine, etc., in addition to the ordinary ingredients of an animal fat.