Iodobismitol in Experimental Syphilis

Abstract

In a previous report, 1 it was shown that iodobismitol (N.N.R.) exerts prophylactic and curative effects on the experimental syphilis of rabbits. Since then, confirmations of the antisyphilitic action in rabbits have been made by Levaditi, Vaisman, Manin and Schoen 2 and by Strandberg and Sjögren, 3 da Nova Gomes and de Oleveira, 4 and Carrillo, Schujman and Campos 5 in clinical syphilis, the latter authors agreeing with Mehrtens and Pouppirt. 6 These reports also contain confirmation of other claims for iodobismitol, namely, electronegativity of iodobismuthite, rapid absorption, sustained excretion, low toxicity and positive cerebrospinal penetration. The chemotherapeutic tests begun in this laboratory 7 years ago have been continued and this report submits the final results on the curative effects of iodobismitol together with some interesting comparisons.

The procedure was the same as that used previously, 1 except that during the past 2 years curative treatment with iodobismitol was given in 3 divided doses within 1 week, instead of 1 single dose. Since 1 week of a rabbit's life (expectancy about 8 years) is equal to about 8 weeks of a man's life (expectancy about 60 years), the treatment-period was the equivalent of clinical medication for 2 months, which is a fairly common initial period in practice. The iodobismitol was injected intramuscularly in a range of doses to permit determination of the minimum effective dose and “therapeutic index”, if possible. The virus was a strain of treponema pallida from a penile chancre, and, by this time, has had 37 passages through rabbits. Fully developed scrotal chancres containing treponema appeared in 3 to 4 weeks after inoculation of the virus. Lymph-node transfers were made 3 months after injection of the bismuth, using generally 3 rabbits, sometimes 4, for tests of lymph-node infectiousness. Virus infected but untreated rabbits were used as controls throughout. Examinations of all rabbits were made routinely in the usual manner. A total of 60 rabbits was used, at least 3 for each dose of iodobismitol. Inasmuch as the results with single and divided doses of the iodobismitol were the same, they were put together, and medians used for the curves in Fig. 1.