For the past two years the literature, more especially that in German, has brought forth the study and evaluation of new anesthetics for local and subcutaneous use. During the first part of 1932 the Hoffmann\x=req- LaRoche Company sent me a quantity of larocaine for trial. During the progress of my study, various authors, to be cited later, have published articles concerning this anesthetic. Therefore, this paper will be presented as a confirmation and substantiation of previously published findings, together with additions which will make the American reader acquainted with the product. Larocaine, a synthetic product, is the p-aminobenzoyl ester of 2,2-dimethyl-3-diethylamino-1-propanol. It is supplied in the form of a hydrochloride, a white crystalline powder soluble in water up to 50 per cent. Chemically, it is akin to procaine hydrochloride and tutocaine. It is stated that the lethal dose for the mouse is 0.3 Gm. per kilogram of body weight by subcutaneous injection, compared with 0.1 Gm. of cocaine, while the lethal dose for the rabbit is 0.15 Gm., compared with 0.07 Gm. of cocaine. These statements have been corroborated in my experiments. The initial pharmacology of larocaine was worked out by Fromherz.1 The chemical formula was found to be (C2H5)2N. CH2C (CH3)2. CH2 OOC. C6 H4NH2. HCl. Fromherz evaluated the drug on the rabbit's cornea and the spinal cord of frogs and found it to be twice as efficient as cocaine in the former, and to have twice the power of procaine hydrochloride in the latter. It was much less toxic on the exposed frog's heart than cocaine. A sublethal dose was excreted in forty-five minutes and could be followed by a like dose at that time without any signs of an accumulated effect. Dietrichs 2 found larocaine to be more rapidly excreted than most of the other benzoyl esters. Epinephrine increased the length of the anesthesia produced by larocaine. In an excellent review and history of the pharmacology of local anesthetics,
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