The relation of hydrogen ion concentration to the action of the local anæsthetics / J.W. Trevan and E. Boock.

  • Trevan, J. W. (John William)
Date:
[1927?]
Catalogue details

Licence: In copyright

Credit: The relation of hydrogen ion concentration to the action of the local anæsthetics / J.W. Trevan and E. Boock. Source: Wellcome Collection.

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    similarity of such dissimilar substances as novocain and cocaine. Changes in both will generally result from any structural change. But Gray’s attempt to augment the physiological activity of cocaine by the substitution of the benzyl and phenyl ethyl group, which were shown by Macht (1918) and Hjort and Eagan (1919) to have some anaesthetic action of their own, has resulted in two compounds for which the molecular anaesthetic value is considerably higher than that for cocaine, while in the case of the benzyl compound the dissociation constant is not appreciably altered. One interesting point which comes out is that the anaesthetic action of /3-eucaine, when reckoned as concentration of free base necessary to produce the effect, is even greater than that of cocaine. CONCLUSIONS. (1) The effect of a series of local anaesthetics on the rabbit’s cornea at different hydrogen ion concentrations is given. (2) Plotting the logarithms of the concentration of the minimal effective concentrations against pH is shown to give lines which for all the mono-acidic local anaesthetics are straight and parallel between pH 5 and pH 8. (3) It is shown that this relationship is consistent with the view that the only active constituent of a solution of local anaesthetic is the free base and not the ion or the undissociated salt. (4) The relationship between the anaesthetic action and pH for a diacidic base, conessine, is shown to confirm this view. (5) Further evidence that the influence of pH is due to dissociation of base is drawn from the fact that variations of pH have no influence on the anaesthetic activity of benzyl alcohol on the cornea. It is shown that variations in the dissociation of the basic anaesthetics do not account for the whole of the difference between them, and that therefore there must be some other relationship between the actual molecular structure of the base itself and its anaesthetic powTer. REFERENCES. Brown, H., and Henry, T. A.—(1923) Trans. Roy. Soc. Trop. Med. and Hyg., 17, 61. Copeland, H. S., and Notton, IT. E.—(1925) Brit. Med. J., 2, 547. Gray, W. H.—(1925) J. Ghem. Soc., 127, 1150. Gros, 0.—(1910) Arch. f. Exp. Path, and Pharm., 03, 80.—-(1912) Ibid., 87, 126. Hjort, A., and Eagan, J. T.—(1919) J. Pharm. and Exp. Ther., 14, 211. ITerridge, P.—(1926) J. of Scientific Instruments, 3, 12. Kolthoff, J. M. — (1925) Biochem. Zeitschr., 182, 289. Macht, D.—(1918) J. Pharm. and Exp. Ther., 11, 263. Regnier, J.—(1924) Bull, des Sci. Pharm., 31, 513.—(19251) Ibid., 32, 271.—(19252) Ibid., 32, 513. Trevan, J. W.—(1925) Biochem. J., 19, 1111. ADLARD AND SON, LIMITED, LONDON AND DORKING. 2
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