LECITHIN PREPARATIONS OMITTED FROM N. N. R.
Report of the Council on Pharmacy and Chemistry
The following report was sent to the manufacturers of the various lecithin preparations mentioned therein. As the replies of the manufacturers were obviously written from the commercial point of view and did not affect the Council’s conclusion that lecithin, when indicated, would be given more advantageously in the form of yolk of egg than in the less pure manufactured product, the Council directed that the report be published, together with extracts from the replies of the manufacturers.
W. A. Puckner, Secretary.
Commercial lecithin preparations are at best very impure substances; all are more or less altered from the original composition. Even with great care, the methods of extraction and drying always produce considerable decomposition; and in some cases the phosphorus and nitrogen contents bear but little relation to the theoretical values. (Long, J. H.: Jour. Am. Chem. Soc., xxx, 881. McLean, Hugh: Chem. Abstracts, May 20, 1915). There is not the slightest reliable evidence that commercial lecithin has any advantage over the lecithin contained in natural foods; the weight of probability is on the other side.
The doses recommended, moreover, are absurdly small; and the amount thus administered is without practical value. Why administer a few milligrams of a more or less decomposed lecithin when it is possible to give a far larger weight of a purer substance in the form of yolk of egg?
In view of these considerations the Council voted that the following proprietary products be omitted from the next edition of N. N. R.:
Glycerole of Lecithin
Lecibrin
Lecithin Solution
Lecithol
Neuro-Lecithin-Abbott
and that the general article on “Lecithin Preparations” be transferred to the annual Council Reports as a matter of record.
The report was submitted to the manufacturers. Their replies were evidently based on commercial consideration, and called for no modification in the report.
The referee recommended that the preceding report be published together with the following extracts from the replies of the manufacturers:
From Armour and Company:
“We are selling a good deal of Lecithol and it seems to be giving satisfactory results in some quarters.... We shall continue to advertise Lecithol along the lines we have employed heretofore.”
From the Abbott Laboratories:
“We can assure you of our confidence in the therapeutic value of Neuro-Lecithin. This has been attested by the reports of favorable results sent us by many physicians, as well as by the periodical literature of the last few years which contains a considerable number of very encouraging references to lecithin therapy.”
From Fairchild Bros. & Foster:
“We would like simply to say that the physician and the Council must be aware of the circumstances and the purposes which actuated us in placing lecithin at disposal, viz., the studies—research—of lecithin and the properties attributed to it and which led to inquiry for and consideration of it. The quantities proposed for medicinal use were not suggested by us; the suggestion of lecithin in small quantities as a therapeutic agent was obviously directed by those who proposed it.... The question whether lecithin, per se, has therapeutic properties in contrast to lecithin as naturally contained in food substances, is something we do not undertake to decide. The Council, on purely theoretical grounds, decides in the negative notwithstanding clinical experience—internal and hypodermic—and thus would deny lecithin the status of a new and nonofficial remedy, worthy of at least tentative progressive clinical consideration. We can only say that we offered bona fide lecithin and that we did not make the investigation of lecithin a pretext for the sale of all sorts of lecithin ‘jumbles’ with lecithin in small proportions, taking their name and making their bid on lecithin.”
Below appears the general article which has been omitted from N. N. R.:
Lecithin Preparations
Lecithins are fat-like bodies belonging to the group of phosphatides. They all consist of glyceryl esters containing two fatty acid radicals and the phosphoric acid radical in which one of the residual hydrogens is replaced by the choline group. The fatty acid may be palmitic, oleic or stearic and various combinations are known to exist; for example, distearyl lecithin, stearyl palmityl lecithin and so on. The commercial lecithins usually include the closely related kephalins.
On saponification the lecithins split more or less readily into choline, the fatty acids and glycerophosphoric acid, and by fusion with alkali nitrate and carbonate they yield alkali phosphate. They occur, free or in combination as lecithoproteins, most abundantly in certain animal tissues, but there are also vegetable lecithins. The lecithins of commerce are obtained usually from yolks of eggs or from calves’ or sheep’s brains.
Numerous processes have been devised for the preparation of lecithin from egg-yolk or animal tissue. From egg-yolk it may be obtained by making an alcoholic extract and precipitating by cadmium chloride. The precipitate is washed with alcohol and ether, mixed with 80 per cent. alcohol and warmed with the proper amount of ammonium carbonate to remove the cadmium. After filtering hot and concentrating the filtrate the lecithin is thrown down by cooling to a low temperature—10 C. or below. The precipitate is taken up in chloroform and reprecipitated by acetone.
From tissues it is obtained by extracting with warm alcohol and ether, concentrating the extract, precipitating with acetone and repeating the operations.
Pure lecithin is white, but the commercial preparations are yellowish-brown wax-like solids, which are not soluble in water but form milky emulsions which exhibit the myeline figures under the microscope. The solubility in cold alcohol or ether is slight, but heat aids it. Lecithins are not soluble in acetone. They are hygroscopic and the water mixtures undergo decomposition on standing. They darken on exposure to air and light.
The alcoholic solution is precipitated by platinum or cadmium chloride. It is decomposed by alkalies with the formation of choline and trimethylamine. The ash contains phosphoric acid. The different lecithins contain from 3.84 to 4.12 per cent. of phosphorus and 1.73 to 1.86 per cent. of nitrogen. The ratio of nitrogen to phosphorus should be at 1 to 2.21.
Lecithin is incompatible with alkalies; it should be kept in well-stoppered bottles and should be protected from the light.
The content of lecithin (plus kephalin) in tissues is about as follows:
| Per Cent. | ||
Egg-yolk | 8 to | 12 |
Egg-white | 0.1 to | 0.2 |
Liver | 2.0 to | 3.0 |
Kidney | 2.0 to | 3.6 |
Lung | 2.0 to | 3.0 |
Pancreas | 2.0 to | 3.0 |
Actions and Uses.—The lecithin preparations have been recommended in many pathologic conditions, especially in malnutrition and sexual debility. Moderate doses are said to bring about a marked retention of nitrogen and phosphorus, but satisfactory proof of this is lacking. It is extremely unlikely that the small doses which have been recommended in pill or tablet form or in emulsions can have any perceptible action, in view of the fact that many of our natural foods contain much greater weights of available lecithins than the medicinal doses provide. There is no good basis for the statement that the free lecithin has a greater food value or is more readily assimilated than is the substance as found in eggs or tissue. The reverse proposition is much more likely to be true, especially when it is considered that the commercial preparations are usually somewhat altered or decomposed in the process of separation.
Dosage.—Given by the mouth in the form of pills, tablets or glycero-alcoholic emulsions. The amount of actual lecithin ingested in this way is usually small because of the doubtful purity of the original preparation. Several doses, as commonly administered, would be required to furnish the amount of lecithin present in a small egg.—(From Reports of Council on Pharmacy and Chemistry, 1915, p. 122.)