Abstract
The purpose of this investigation was to determine whether any differences were to be observed in the relative anesthetic effects over widely different pH ranges, comparing a series of general anesthetics with a series of local anesthetics and a series of hypnotics. Alcohols such as allyl and isoamyl, and also general anesthetics such as chloroform, ether, chloretone, etc., do not form salts and consequently their distribution between oil and water is not markedly changed by a change in the (H+) concentration of the water phase.
Local anesthetics like neothesin, cocaine and butyn are lipo-soluble organic bases with relatively low solubility as free bases in water, but in the presence of acids they form water-soluble salts. Consequently the oil-water distribution coefficient shifts from a high oil-solubility and low water-solubility on the basic side, to a low oil-solubility and high water-solubility on the acid side.
In the case of the barbituric acid hypnotics exactly the reverse relation is found. The barbituric acids are lipo-soluble organic acids possessing very low water-solubility but on addition of alkali to the water phase water-soluble salts of the barbituric acids are formed. Consequently the distribution coefficient shifts from a high oil-low water solubility on the acid side, to a low oil-high water solubility on the basic side.
It follows from the above that if the induction of anesthesia is in any measure dependent upon the lipoid-water distribution coefficient of the anesthetic a shift from the acid or neutral to the basic side should exert little or no effect on the alcohols and general anesthetics, should increase the effect of bases like cocaine and decrease the effect of pseudo acids of the barbituric acid type.
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