Cod-liver oil (Oleum Jecoris Aselli) is extracted from the fresh liver of the cod, Gadus Morrhua, Linn. (Order Teleostei), and other species of Gadus (U.S.P.) by the application of low-pressure steam at a temperature not exceeding 82°, after which it is cooled to -5°, and the frozen mass submitted to pressure in canvas bags, the purified oil being forced through the canvas, and a whitish tallow-like mass, of so-called "stearine" and liver debris, being left in the bags. The product is known as "non-freezing" oil, because it does not readily become turbid when exposed to low temperatures. It occurs as a pale yellow, thin, oily liquid, with a slight fishy, but not rancid, odour, and a bland, slightly fishy taste. Inferior or old oils are liable to be dark coloured, acrid or bitter, unduly acid, and more or less rancid. Specific gravity, 0.920 to 0.930 (0.915 to 0.925 at 25°); refractive index, 1.480 to 1.483; iodine value, 155 to 173; saponification value, 179 to 192. The acidity calculated as oleic acid and determined by titration with decinormal alcoholic potash, should not exceed 1.5 per cent. On distillation with ammonia, cod-liver oil yields trimethylamine, being thus distinguished from other fixed oils used in medicine. It is stated in the B.P. that cod-liver oil may be distinguished from seal oil or vegetable oils by the violet colouration produced by the addition of a drop of sulphuric acid (specific gravity, 1.843) to a few drops of the oil on a porcelain slab, the presence of cholesterol being thus indicated, but the colour is not always produced. Adulteration with other fish oils or vegetable oils is shown by the separation of solid fat on cooling to 0° for two hours. Oils from other species of Gadus have analogous properties to cod-liver oil, and are difficult to detect when mixed with it, being distinguishable only by odour and taste. Adulteration with mineral oil is readily ascertained by the determination of the saponification value, and of unsaponifiable matter, which should not exceed 1.5 per cent. Cod-liver oil absorbs a considerable amount of oxygen on exposure to the air, and becomes thicker, though without drying. Hence the presence of any notable quantity of linseed oil would be indicated by the film test. If 5 centimils (0.05 milliliters) of cod-liver oil be dissolved in 1 mil of chloroform, and the solution shaken with 5 centimils (0.05 milliliters) of sulphuric acid, it will acquire a violet-red tint, rapidly changing to rose-red, and finally, brownish-yellow. If about 1 decimil (0.1 milliliters) of fuming nitric acid be allowed to come gradually into contact with about 5 decimils (0.5 milliliters) of the oil contained in a watch-glass, a red colour will be produced where the liquids meet. On stirring the mixture with a glass rod, this colour becomes bright rose-red, soon changing to lemon-yellow (distinction from seal oil, which shows at first no change of colour, and from other fish oils, which become at first blue and afterwards brown and yellow).
Very slightly soluble in alcohol, readily soluble in chloroform or carbon bisulphide, soluble in ether (1 in 2), acetic ether (about 1 in 4).
Constituents.—The chief constituents of the oil are jecolein and, therapin, the glycerides of jecoleic acid, C19H36O2, and therapic acid, C17H26O2; other constituents are palmitin, the glycerides of one or more unknown acids, and traces of cholesterol, alkaloidal bodies (aselline, morrhuine, etc.), bile acids and iodine, while the glycerides of acetic, butyric, valeric, and capric acids sometimes occur as secondary products in oil of inferior quality, owing to putrefaction of the livers. Jecoleic acid is a very unstable compound belonging to the same series as oleic acid, and is probably isomeric with doeglic acid. Minute quantities of iron, manganese, magnesium, calcium, and sodium have been identified in the oil.
Action and Uses.—Cod-liver oil is a food rather than a drug, and is the most easily assimilable of all fats. It increases weight and improves the general condition of the patient, being often well borne by those who are unable to digest other fats. It is employed to improve nutrition in all wasting diseases, such as tuberculosis, scrofula, and rickets. In the malnutrition of children, small doses taken after each meal are of the greatest service. It is best given in the cold months of the year, as a distaste for the oil frequently arises in the summer months. It should not be given when there is diarrhoea. For young infants, the oil is sometimes applied by inunction with good results. On the now abandoned assumption that ready absorption of cod-liver oil was due to the large proportion of free acid present, substitutes consisting of vegetable oils with the addition of oleic acid have been suggested. Lipanin is a mixture of olive oil with 6 per cent. of oleic acid. Morrhuol is an alcoholic extract of cod-liver oil, containing the bases without the fatty glycerides. Morrsiccol is a pale buff-coloured powder containing 36.6 per cent. of cod-liver oil combined with mineral matter. Cod-liver oil may be administered in the form of emulsion, or as Extractum Malti cum Oleo Morrhuae, when the plain oil causes nausea. Emulsions are also prepared with the hypophosphites of calcium and sodium, for use in phthisis. Capsules of cod-liver oil are prepared, containing 1 to 4 mils (15 to 60 minims) in each.
Dose.—4 to 16 mils (1 to 4 fluid drachms).
- Emulsio Olei Morrhuae, B.P.C.—EMULSION OF COD-LIVER OIL. 1 in 2.
- Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsio Olei Morrhuae, C.F.—EMULSION OF COD-LIVER OIL, C.F.
- Cod-liver oil, 50; gum acacia, in fine powder, 12.5; solution of gluside, 0.7 (or tolu syrup, 10); flavouring to suit; distilled water, sufficient to produce 100.
- Emulsio Olei Morrhuae Composita, B.P.C.—COMPOUND EMULSION OF COD-LIVER OIL. 1 in 2.
- Being free from sugar this emulsion is suitable for diabetic patients. Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsio Olei Morrhuae, cum Ferri Phosphato, C.F.—EMULSION OF COD-LIVER OIL WITH PHOSPHATE OF IRON.
- Cod-liver oil, 50; soluble ferric phosphate, 1.38; gum acacia, in powder, 12.5: syrup of orange, 6.25; syrup of tolu, 6.25; distilled water, sufficient to produce 100. A primary emulsion is made with the oil, gum, and 25 of the water, and the syrups are then added with constant stirring; the soluble ferric phosphate is next dissolved in 8.75 of water and added to the mixture, and finally sufficient distilled water to make 100.
- Emulsio Olei Morrhuae, cum Ferro, B.P.C.—EMULSION OF COD-LIVER OIL WITH IRON.
- Each fluid ounce contains 4 grains of iron and ammonium citrate, with emulsion of cod-liver oil. Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsio Olei Morrhuae, cum Glycerophosphatibus, B.P.C.—EMULSION OF COD-LIVER OIL WITH GLYCEROPHOSPHATES.
- Contains 50 per cent. of cod-liver oil with the glycerophosphates of calcium, iron, magnesium, potassium and sodium, glycerophosphoric acid, yolk of egg, and flavouring agents. Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsio Olei Morrhuae, cum Hypophosphitibus, B.P.C.—EMULSION OF COD-LIVER OIL WITH HYPOPHOSPHITES.
- Contains 50 per cent. of cod liver oil, emulsified with yolk of egg, with the hypophosphites of sodium and calcium, and flavouring agents. Used especially in phthisis. It is sometimes made with sherry instead of distilled water, and should then be distinguished as Emulsio Olei Morrhuae, cum Hypophosphitibus et Vino. Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsio Olei Morrhuae, cum Pepsino, C.F.—EMULSION OF COD-LIVER OIL, WITH PEPSIN. Syn.—Phosphatic Emulsion.
- Cod-liver oil, 144 fluid ounces; the yolks of twenty-four eggs; glycerin, 74 fluid ounces; refined sugar, 40 ounces; compound powder of acacia, 4 1/2 ounces; lime water, 75 fluid ounces; diluted phosphoric acid, 9 fluid ounces; essence of pepsin, 24 fluid ounces; flavouring, as required. The yolks are rubbed in a mortar (whites of half this number of eggs may be added with advantage) to a smooth paste, and the glycerin and compound powder of acacia added; the cod-liver oil is then added in portions of about 8 fluid ounces, and when emulsified the lime water containing the sugar in solution is stirred in vigorously; next, the diluted phosphoric acid, and, finally, the essence of pepsin, and vigorous stirring continued for fifteen minutes. The emulsion is allowed to stand for two hours, and strained through dairy cloth.
- Emulsio Olei Morrhuae Pancreatica, B.P.C.—PANCREATIC EMULSION OF COD-LIVER OIL.
- Contains 50 per cent. of cod-liver oil, emulsified with gum acacia, tragacanth, and solution of potassium hydroxide; with glycerin of pancreatin, stronger glycerin of pepsin, and flavouring agents. It is free from sugar and therefore suitable for diabetic patients. Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsio Olei Morrhuae Pancreatica cum Chondro, B.P.C.—PANCREATIC EMULSION OF COD-LIVER OIL WITH IRISH MOSS. Syn.—Cremor Olei Morrhuae Pancreaticus; Pancreatic Cod-liver Oil Cream.
- Contains 50 per cent. of cod-liver oil emulsified with Irish moss, with the addition of glycerin of pancreatin, stronger glycerin of pepsin, and flavouring agents. It is an easily assimilable emulsion. Dose.—8 to 30 mils (2 to 8 fluid drachms ).
- Emulsio Olei Morrhuae Pancreatica cum Malto, B.P.C.—PANCREATIC EMULSION OF COD-LIVER OIL WITH MALT EXTRACT. Syn.—Cod-liver Oil with Pancreatin and Malt.
- This emulsion contains 50 per cent. of cod-liver oil, emulsified with gum acacia, tragacanth, and saccharated solution of lime; with glycerin of pancreatin and extract of malt. The addition of extract of malt renders it a highly nutritive preparation. Dose.—8 to 30 mils (2 to 8 fluid drachms).
- Emulsum Olei Morrhuae cum Hypophosphitibus, U.S.P.—EMUSION OF CODLIVER OIL WITH HYPOPHOSPHITES.
- Cod liver oil, 50; gum acacia, in fine powder, 12.5; calcium hypophosphite, 1; potassium hypophosphite, 0.5; sodium hypophosphite, 0.5; syrup, 10; oil of gaultheria, 0.4 (or other suitable flavouring agent); water, sufficient to produce 100. Average dose.—8 mils (2 fluid drachms).
- Emulsum Olei Morrhuae, U.S.P.—EMULSION OF COD-LIVER OIL, U.S.P.
- Cod-liver oil, 50; gum acacia, in fine powder, 12.5; syrup, 10; oil of gaultheria, 0.4 (or other suitable flavouring); water, sufficient to produce 100. Average dose.—8 mils (2 fluid drachms).
- Vinum Olei Morrhuolis, C.F.—WINE OF MORRHUOL.
- Morrhuol (gaduol), 0 46; liquid extract of liquorice, 7.5; glycerin, 5; syrup of wild cherry, 10; liquid extract of malt, 20; compound syrup of hypophosphites, 10; fuller's earth, in powder, 1.5; sherry, sufficient to produce 100. The morrhuol is mixed with the glycerin, fuller's earth and the liquid extracts and syrup of wild cherry, and allowed to stand for twenty-four hours with occasional agitation. The product is filtered, the syrup of hypophosphites added, and finally, sufficient sherry to produce 100.
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.