This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Under the impression that lactic acid is ordinarily present in the gas-ric juice, that it is consequently the form of lactate which the ferruginous preparations introduced into the stomach generally assume, and that in this form they enter the circulation, MM. Gelis and Conte were induced to recommend the use of the lactate of iron in medicine, as more likely than other chalybeates to find its way readily into the blood, and to produce the required effects on the system. Some trials that were made confirmed their views as to the efficiency of the salt, and it was for a time con-siderably used; but further experience has shown that it is not superior to other salts of iron; and, from the experiments of Quevenne, it would appear that it is no less liable than others to undergo precipitation in the stomach.
It may be made either, as directed in the U. S. Pharmacopoeia, by di-gesting iron filings in lactic acid, or by double decomposition between lactate of lime and sulphate of iron. In the former case, the iron is protoxidized at the expense of the water, and then combines with the acid to form a lactate of the protoxide; in the latter, the same salt remains in solution after the precipitation of sulphate of lime. The lactate may be obtained from the solution in crystals in the ordinary mode, or in the form of scales by evaporating to the consistence of syrup, and then spreading thinly on glass or porcelain to dry.
Lactate of protoxide of iron is in greenish-white crystalline grains or crusts, of a mild ferruginous taste, little changed on exposure to the air, slowly and sparingly soluble in water, and scarcely soluble in alcohol. The watery solution becomes yellowish on exposure, in consequence of the partial sesquioxidation of the protoxide; and the dry salt is sometimes met with of the same colour, probably from the same cause, or from want of care, in its preparation, to avoid this source of impurity.
In its effects on the system, lactate of iron is not unlike the sulphate. but is less astringent. It is capable of exciting, and, in over-doses, of irritating the stomach, and may, therefore, be used as a gastric stimulant in dyspepsia, though less efficient than some others in diarrhoea, and hemorrhage from the mucous membrane of the primae viae. It may also be employed to produce the effects of iron on the system at large; but is inferior for this purpose to powdered iron, or the pill of the carbonate, or even to the milder soluble salts, as the tartrate of iron and potassa, and the tartrate or citrate of iron and ammonia, because more liable to irritate the stomach when freely administered,and consequently incapable of imparting so much iron to the circulation within a given time. The dose is one or two grains, three times a day, which may be gradually increased so as to amount to twelve grains daily. It may be given in powder, pill, or syrup.