Acidum Lacticum

Lactic Acid

Lactic acid; acide lactique, Fr.; Milchsäure, Ger.

Properties

It is an acid, sirupy liquid, which contains 75 per cent of absolute lactic acid, and has a pale wine-color. Specific gravity, 1·212. It mixes in all proportions with water, alcohol, and ether.

Incompatibles and Antagonists

Alkalies and the mineral salts.

Synergists

Pepsin, sodium chloride, vegetable acids, chlorhydric acid, etc.

Dose

Fifteen minims to 3 ss in water before or after meals, according to the conditions present.

Physiological Action

As lactic acid is a frequent constituent of the gastric juice, it has undoubtedly an important function in connection with digestion. Used medicinally, it promotes the appetite and facilitates digestion. In large doses (3 j) it gives rise to epigastric pain, flatulence, and loss of appetite. As lactic acid is one of a series of homologous acids, containing butylactic, valerolactic, and leucic acids, it is not improbable that some of these may result from its oxidation when administered in excess. It probably combines with bases and forms lactates, for it displaces not only the volatile but some of the mineral acids from their combinations. Chemical investigations have indeed confirmed this, for, besides free lactic acid, lactates have been found in the gastric juice. It is not known definitely whether , free lactic acid occurs in the blood in the healthy state, but it certainly does in some morbid conditions. According to Lehmann, lactates are rapidly converted into carbonates in the blood. Free lactic acid, as was long ago shown by Berzelius, is found in muscular fluid, and has also been detected in the spleen by Scherer. Although it is not always a constituent of normal urine, yet, when the supply of lactates to the blood is considerably beyond the oxidizing power of the blood, it has been found (Lehmann). Scherer has shown also that lactic acid is present in the exudates of puerperal fever.

Lactic acid has the power to dissolve a considerable quantity of freshly-precipitated phosphate of lime.

The suggestion made by Prout, of a relation between an excess of lactic acid in the blood and rheumatic inflammation, received a remarkable confirmation in the experiments of Richardson, who produced endocardial inflammation by injecting lactic acid into the peritoneal cavity of dogs. Further confirmation of this connection has been afforded in the attacks of acute rheumatism which have occurred in subjects of diabetes treated by lactic acid.

Therapy

Solutions of lactic acid are of great utility as solvents of false membrane. Since the comparative demonstration of solvents made by Bricheteau and Adrian, it has been employed successfully by Dr. Weber, of Darmstadt, and Dr. Dureau, in croup, applied by means of a pulverisateur in the strength of thirty to forty drops to the ounce (Waldenburg), and is also advocated by Morell Mackenzie and Lennox Browne. The following is the formula used by Mackenzie at the London Throat Hospital : Rx Acidi lactici, 3 iijss ; aquae destil., oz χ. M. This may be used in a spray-producer, or be applied on a mop to the affected part. It is unquestionably an excellent solvent of the exudation of diphtheria, as the author has frequently observed. It may be used also as a gargle when the exudation does not extend beyond the tonsils and the pillars of the fauces. For this purpose sufficient acid may be added to water to give a distinctly sour taste. As the application is free from danger, it may be used as often as every half-hour. When used in the form of spray, care must be had to prevent the acid hurting the eyes.

Chiefly in atonic dyspepsia is lactic acid employed. In this condition it is, so to speak, a physiological remedy, being a constituent of the gastric juice ; therefore it is supplied artificially, because the stomach is unequal to the task of producing it. Generally, it is advisable to combine pepsin with it thus : Rx Liq. pepsinae, 3 xij ; acidi lactici, 3 iv. M. A teaspoonful three times a day after meals is a proper dose for an adult. In the apepsia of infants, characterized by the presence of undigested aliment in the discharges, this combination is an excellent remedy. If a marked degree of acidity exists, the acid should be omitted, or given before the milk, when it may prevent the excessive production of acid. In irritative dyspepsia, when the pain and suffering are due to slow and imperfect digestion, lactic acid will often give great relief, either alone or combined with pepsin. Cases of acidity and heartburn are often quickly relieved by lactic acid given before meals. When the presence of an excess of the phosphates, uric acid, and the urates, and of oxalate of lime, in the urine, is due to imperfect digestion and faulty assimilation, as is frequently the case, lactic acid is serviceable. Dr. Deecke advocates the use of lactic acid in chronic cystitis, as a means of arresting the ammoniacal decomposition of the urine, a condition in which he holds it to be very effective.

Lactic acid has been used with varying success in the treatment of diabetes. The object to be gained is the prevention of sugar formation from the starchy and other elements of the food. Dr. Foster reports some cases apparently decidedly benefited, and Dr. Ogle gives an account of two cases in which no good results were attained. Cases have been lately reported in which the patients were improved by the use of lactic acid, but, on the whole, the utility of this agent in diabetes must be held to be as yet subjudice, besides the danger of setting up an endocarditis, or other changes in the intima of the vessels, that might be even more serious than the malady for which prescribed

Authorities referred to above :

Bricheteau, Dr. Felix. Bulletin General de Thérapeutique, vol. lxxiv, p. 72.

Butler, Dk. N. L. Treatment of Croup by Lactic-Acid Spray. The Practitioner vol. vii. p. 1S9.

Dureau, Dr. Bulletin General de Tliérapeutique, vol. lxxxiii, p. 45.

Jaffé, Dr. Die Diphtherie. Schmidt's Jahrbücher der gesammten Medicin, vol. cxlix, p. 321.

Ogle, Dr. John W., and Dr. Balthazer Foster. British Medical Journal.

Lehmann, Prof. Dr. C. G. Physiological Chemistry, American edition, vol. i, p. 85, et seq

Mackenzie, Dr. Morell. The Pharmacopoeia of the Hospital for Diseases of the Throat, London, 1872.

Nothnagel, H. Handbuch der Arzneimittellehre, Berlin, 1870, p. 376.

Ranke, Prof. Dr. J. Grundzüge der Physiologie des Menschen, zweite Auflage, Leipzig, 1872, p. 248.

Waldenburg, Dr. L. Die locale Behandlung der Krankheiten der Athmungsorgart, Berlin, 1872, p. 403.