Toxic effects of a new boron containing heterocycle: 4,4,8,8-tetraethyl-3,3a,4,8-tetrahydro 3a,4a,4-diazabora-S-indacene.

LD50 values in mice for 4,4,8,8-tetraethyl-3,3a,4,8-tetrahydro-3a,4a,4-diazabora-S-indacene (Myborin) were determined by the ip, po, and sc routes. The LD50 value for ip was 69.5 mg/kg found by the method of Litchfield and Wilcoxon, with upper and lower confidence limits of 77.8 and 62.1 mg/kg. Oral and sc LD50's were approximated after the method of Deichmann and LeBlanc and were found to be 180 mg/kg (po) and 420 mg/kg (sc). Each of these values has a confidence range of +/- 30%. Myborin induced convulsions, hyperreflexia, and death accompanied by tetany when given by either the ip or oral routes. Moreover, Myborin induced porphyria in animals surviving for 24 hr after these routes of administration and in virtually all animals dosed sc. Death by the sc route is probably a result of acute porphyria. Hepatomegaly and skin photosensitivity were demonstrated to be profound. Boron levels in the livers of mice were determined colorimetrically 24 hr after ip injections of Myborin and in untreated control mice. The quantity of boron found in the experimental group was 15.46 mug/g wet liver as compared to 8.11 mug/g wet liver for controls (P less than 0.01). The difference corresponds to 23% of the injected quantity of boron.