Oleum Morrhuae. U. S., Br. Cod Liver Oil.
Ol. Morrh. [Oleum Jecoris Aselli]
"A fixed oil obtained from the fresh livers of Gadus morrhua Linné and of other species of Gadus (Fam. Gadidae). Preserve it in a cool place, in well-closed containers, which have been thoroughly dried before filling." U. S. "Cod-liver Oil is the oil expressed from the fresh liver of the cod, Gadus morrhua, Linn., at a temperature not exceeding 85° C. (185° F.), and from which solid fat has been separated by filtration at about -5° C. (23° F.)." Br.
Oleum Hepatis Morrhuae; Cod Oil; Huile da Foie de Morue, Fr. Cod.; Huile de Morue, Fr.; Oleum Jecoris Aselli, P. G.; Leberthran, Stockfischleberthran, Dorschleberthran, Kablianleberthran, G.; Olio di fegato di merluzzo, It.; Aceite de higado de bacalao, Sp.
Gadus morrhua, Linn.; Morrhua vulgaris Storer.—The common cod is between two and three feet long, with brown or yellowish spots on the back. The body is moderately elongated and somewhat compressed, and covered with soft, rather small scales, being quite conspicuous also on the head. Of the fins, which are soft, there are three on the back (dorsal), two anal, and a distinct caudal, and the fin (ventral) under the throat is narrow and pointed. The jaws are furnished with pointed irregular teeth, in several ranks. The gilla are large, with seven rays. This species of cod inhabits the cold waters of the Northern Atlantic, and is especially abundant on the Banks of Newfoundland, where it finds food adapted to its wants.
Besides the common cod, several other species of Gadus, frequenting the seas of Northern Europe and America, contribute to furnish the cod liver oil of commerce. Among these De Jongh mentions Gadus callarias, or dorsch (Morrhua americana of Storer), G. molva, or ling, G. carbonarius, or coal fish, and G. pollachius, or pollack, as affording the oil on the coast of Norway, where from 17,000,000 to 35,000,000. of codfish are annually taken. For an account of the mode of fishing for cod and of preparing the oil practised in Norway and Denmark, see P. J., April, 1877, p. 810; N. R., March, 1878; Ph. Ztg., 1900, 261; Ph. Era, 1904, 111; C. D., 1904, 21.
On the American coast, in addition to the pollack above mentioned, it is obtained also from the hake (G. merluccius. and the haddock (G. aeglefinus.. It is produced on our coast north of Boston. The oil is also largely produced in Newfoundland, Great Britain, Norway, and to some extent in Iceland.
Preparation.—Fishermen were for a long time in the habit of collecting this oil, which was largely consumed in the arts, particularly in the preparation of leather. Upon the coasts of Newfoundland, Nova Scotia, and New England, the boats which fish near the shore, being small, soon obtain a load, and, running in to land, deliver their cargoes to persons whose business it is to cleanse and salt the fish. The oil was formerly prepared in the huts of the fishermen, but is now prepared more largely at establishments to which the livers are conveyed in quantities. These are put into a boiler with water, and heated until they are broken up into a pultaceous mass, which is thrown upon a strainer covering the top of a cask or tub. The liquid portion passes, and upon standing separates into two parts, the oil rising to the surface of the water. The oil is then drawn off, and, having been again strained, is prepared for the market. Another and improved method, which has come into use since the extensive employment of the oil as a medicine, is to heat the livers in a wooden butt by means of low pressure steam. The pultaceous mass resulting is drained as before mentioned—the livers themselves containing, besides oil, a considerable portion of aqueous fluid, which passes off with it in the form of emulsion and separates on standing. In the case of the finest American varieties, the oil, which is made only in the winter months, is drawn off by taps from the bottom of the cooking butt, and then put into a cooling house to freeze. The solid frozen mass is put into canvas bags, and submitted, while at a low temperature, to severe pressure, whereby the pure liquid oil is forced out, leaving a whitish, tallow-like mass, composed of stearin and liver debris. This residue is sold to the soap makers, and the oil bottled without further process. The oil thus variously procured was called shore oil, and is the purest kind. The manufacture of refined oil by improved processes is developing rapidly in Newfoundland. (See West. Drug., 1897, 13.)
Formerly the crews of the larger boats, which fish upon banks far from land, cleansed the fish on board, and, throwing the offal into the sea, put the livers into barrels or other receptacles, where they underwent a gradual decomposition, the oil rising to the surface as it escaped from the disintegrating tissue. From this was obtained the so-called "Straits oil" and "banks oil." The method is, however, no longer in vogue and these form's of the oil are unknown in commerce. For further details see U. S. D., 19th edition, p. 857, and A. J. P., xxiii, 97; xxvi, 1. Large quantities of Norwegian cod liver oil are sold in the United States; the method of extraction depending on the action of steam does not differ greatly from that used in America. Another oil is made by the cold process and B. Rauitz, Ph. Ztg., 1900, 261, furnishes the following account: The fresh livers, separated from the gall-bladder, are placed in a wooden tub, 5 feet in height by 7 feet in diameter, until the tub is nearly full, which is then left exposed to the action of the sun, shining day and night in these high latitudes. After about three weeks the extraction is completed, and, owing to the favorable atmospheric conditions' and the evident absence of germs in this far polar region, not the slightest evidence of decomposition manifests itself during this process. The oil runs off pure and simply has the odor characteristic of cod liver oil, and while the "steam cod liver oil" requires refining, that obtained by the "cold process" described is ready for the market as run off from the tubs. This explains why in more southerly latitudes it is impossible to prepare a satisfactory cod liver oil; the cold process is not available, while the steam process does not yield a desirable oil.
The oil is sometimes procured by expression. Donovan recommends the following plan, which affords a very fine oil. The livers, perfectly sound and fresh, are to be placed in a clean iron pot over a slow fire, and stirred until they assume the condition of a pulp, care being taken that the mass be not heated beyond 88.9° C. (192° F.). When this temperature is attained, the pot is to be removed from the fire, and its contents introduced into a canvas bag, through which water and oil will flow into a vessel beneath. After twenty-four hours, the oil is to be decanted and filtered through paper. In this state it is pale yellow, with little odor, and a bland not disagreeable taste.
The chemical composition of the glycerides in cod liver oil is very complicated. Palmitic and stearic acids are present. But the so-called "stearin" separating from cod liver oil on cooling contains some unknown unsaturated compounds, as the cod liver stearin has a very high iodine value (113.4, Heyerdahl; 94, Lewkowitsch). The glycerides of the lower fatty acids, such as acetic, butyric, valeric, and capric acids, stated by various authors to occur in cod liver oil, are according to Salkowski and Steenbuch, secondary products due to the putrefaction of the livers. The researches of Heyerdahl (Cod Liver Oil and Chemistry, P. Moller, London, 1895) give as present in the mixed fatty acids about 4 per cent. of palmitic acid, 20 per cent. of jecoleic acid, C19H36O2, and 20 per cent. of therapic acid, C17H26O2, morrhuic acid, C9H13O3N, and asellic acid, C17H32O2, have also been reported. The former is a nitrogenous compound and is supposed to be identical with a basic substance named gaduine which had been reported. Heyerdahl states that in the fresh state cod liver oil contains no hydroxy-acids.
A characteristic constituent of cod liver oil is cholesterol, which can be isolated by saponifying the oil and exhausting the soap with ether. The quantity of cholesterol, according to Alien and Thomson, is from 0.46 to 1.32 per cent. By reaction with ammonia in distillation the oil yields a volatile alkaloid, trimethylamine, C3H9N, which has a strong pungent odor, recalling that of herring pickle, of which the same alkaloid is an ingredient. No other official fatty oil yields a similar product. (See A. J. P., xxiv, 343.) Gautier has obtained from cod liver oil the leucomaines butylamine, iso-amylamine, hexylamine, and dihydrolutidine, and two fixed bases, aselline, C25H32N4, and morrhuine, C19H27N3. Aselline was found by its discoverer to be relatively feeble physiologically; morrhuine, of which about 2 milligrammes are believed to exist in a tablespoonful of ordinary cod liver oil, is affirmed to have the properties of exciting the appetite and acting as a powerful diuretic and diaphoretic. Besides these bases, an acid containing nitrogen has been found. This acid, morrhuic acid, CeHiaNOa, is probably identical with De Jongh's gaduine. Some have been disposed to ascribe the virtues of cod liver oil to its iodine and bromine, but these are in too small proportion for any effect, and the oil has produced results which have never been obtained from iodine and bromine themselves. The presence of iodine cannot be detected by the usual tests. It is necessary to convert the oil into a soap, and to carbonize this, before it will give evidence of iodine. The proportion never exceeds 0.05 per cent., or 1 part in 2000, and it is by no means certain that iodine is always, if ever, present in pure oil. The proportion of iodine present has been investigated by E. C. Stanford (P. J. , xiv, 353), who found it to be extremely minute, ranging from 0.00138 to 0.00433 per cent., with an average of 0.00322 per cent. The oil is capable of dissolving a larger proportion of iodine, and, if any specimen contain more than 0.05 per cent., there is reason to suspect that iodine has been added. Cod liver oil becomes rancid so easily that it contains varying amounts of free fatty acids, frequently showing their presence, even when freshly rendered. Medicinal oils, however, should not show more than from 0.3 to 0.7 per cent. of free add, calculated as oleic acid.
The so-called active principles of cod liver oil which are found in the market under various names indicative of their origin are usually made by alcoholic extraction of the oil or of the livers themselves. They consist almost entirely of crude fatty acids, no iodine, bromine or phosphorus is detectable, the bases which are sometimes present are in very minute amount, and are probably of the ptomaine type, derived from partly decomposed products. These so-called alcoholic extracts or active principles are themselves scarcely soluble in diluted alcoholic' menstrua, such as are used in preparing the so-called "tasteless" preparations of cod liver oil, so that such preparations can possess little or no activity due to cod liver products.
Uses.—Dr. Owen T. Williams (P. J., 1912, p. 806), in discussing the subject of cod liver oil from the pharmacological and biochemic standpoint, states that the idea that the value of cod liver oil is due to the presence of infinitesimal amounts of constituents, such as sulphur, iodine, phosphorus, etc., is not true, but that its peculiar effectiveness in tuberculosis is intimately associated with its food value and is due to the fat itself, which being free from phosphates and consisting almost entirely of unsaturated fatty compounds is a different type of fat from those usually administered or found in foods of the oils on the market. He states that those have the greatest value which have been prepared under the most favorable conditions to prevent oxidation.
The questions of the way in which cod liver oil exercises its beneficent influence in morbid conditions, 'and to which of its numerous ingredients it owes its therapeutic value, are still matters of difference of opinion. Formerly many attributed its actions to the traces of iodine, phosphorus, or organic bases it contained. This view has, however, been generally abandoned; the extracts containing these principles separated from the oil have not yielded the same results. The therapeutic virtues, therefore, apparently reside in some of the constituents of the oil itself. Whether or not it acts simply as a foodstuff or whether it has some direct influence on the bodily metabolism, is open to dispute. It seems pretty well established that not only is cod liver oil absorbed from the intestinal tract better than any other fats, but that it actually increases the utilization of other forms of fatty foods. An interesting observation has been made by Osborne and Mendel that young rats who have been fed on a diet containing no form of fat but lard until their growth has ceased, will immediately recommence growing when cod liver oil is substituted for the lard. Williams (B. M. J., 1912, ii, p. 700) believes that the unsaturated fatty acids have -a direct inhibiting effect on the growth of the tubercle bacilli which may in part explain its action in tuberculosis.
Cod liver oil is used in all forms of malnutrition, especially, however, in various forms of tuberculosis. The old idea that it had a specific influence in this infection is probably incorrect, but in the reaction against its use the pendulum has swung too far and it is ofttimes neglected or even condemned in cases in which it might be well employed. It is often of service in those types of chronic rheumatism or gout which are associated with malnutrition, and has been highly lauded in rickets and other diseases of the bones. It is unique among the oils in that it is absorbable through the skin, at least by young infants, in sufficient quantity to have a perceptible influence upon nutrition.
Various measures have been recommended for overcoming the objectionable taste which is a great obstacle to the wider use of this remedy. None of these, however, are entirely successful. It is most frequently exhibited in the form of one of the numerous emulsions upon the market, of which that with malt extract is one of the best. It is sometimes given in flexible capsules, but these have the objection that they can only hold comparatively small doses. Dufourmantel (J. P. C., June, 1864) prepared a jelly by dissolving half a drachm of ichthyo-colla in as little hot water as possible, and them gradually mixing with it a fluidounce of the oil with four drops of the oil of anise, taking care-that the temperature should not rise above 24° C. (75.2° F.).
Phosphorized cod liver oil may be made by-dissolving one grain of phosphorus in four fluid-ounces of cod liver oil.
Glyconin Emulsion of Cod Liver Oil.—The formula proposed by Close, and at one time largely used 'by Andrews, Beard, and others, is as follows: Cod liver oil, 4 fluidounces; glyconin, 9 fluidrachms; aromatic spirit of ammonia, 1 fluidrachm; sherry wine, 2 fluidounces, diluted phosphoric acid, 4 fluidrachms, essence of bitter almond (made by dissolving 1 fluidrachm of the volatile oil in half a pint of alcohol) 2 fluidrachms. The cod liver oil is to be added very slowly to the glyconin with brisk stirring, and the other ingredients added in the order named. Glyconin or Glyceritum Vitelli is made by mixing 45 Gm. of fresh yolk of egg with 55 Gm. of glycerin.
The following is Carlo Pavesi's formula for deodorized cod liver oil. Cod liver oil, 1000 parts; ground roasted coffee, 50 parts; animal charcoal, 25 parts. Place the ingredients in a flask, which is to be well closed, and digest on a. water bath during the space of one hour; them set it aside for three days, occasionally shaking' the contents, and filter. This preparation has; a peculiar coffee flavor, and is quite pleasant to take, 'the only objection being the liability to cultivate in the patient a distaste for using coffee as a beverage. (N. R., Jan., 1876.)
The olein of cod liver oil has been recommended by Arthur Leared, when the oil itself disagrees with the stomach. He has found it to produce the same remedial effects, and to be borne much better. It may be given in the same dose. A solution of quinine in the oil may be made by heating the freshly precipitated alkaloid with the oil, in the proportion of two grains to a fluidounce, by means of a water bath, until the mixture becomes quite clear.
Dose, one to four fluidrachms (3.75-15 mils).
Off. Prep.—Emulsum Olei Morrhuae, U. S., Emulsum Olei Morrhuae cum Calcii Lactophosphate, N. F.; Emulsum Olei Morrhuae cum Calcii Phosphate, N. F.; Emulsum Olei Morrhuae cum Malto, N. F.; Emulsum Olei Morrhuae cum Hypophosphitibus, N. F.; Emulsum Olei Morrhuae cum Pruno Virginiana, N. F.; Emulsum Olei Morrhuae cum Vitello, N. F.