Inhibition of hepatic azo-reductase and aromatic hydroxylase by radiopharmaceuticals containing tin

Mice given single i.v. doses of some radiopharmaceuticals containing stannous chloride as a reducing agent, showed significant inhibition of hepatic azo-reductase and aromatic hydroxylase activity at dose levels which contained as little as 0.2 mg/kg of stannous chloride. Cytochrome P-450 content was also reduced significantly. Some of the above radiopharmaceuticals would have to be injected at approx. 10 times the maximum recommended human dose to reach a 0.2 mg/kg dose level of stannous chloride in man, provided other sources of stannous ion were excluded.