The fate of ethyltin and diethyltin derivatives in the rat.

1. Ethyltin trichloride does not appear to be metabolized by the rat. When given orally excretion occurs almost entirely in the faeces, and when given intraperitoneally it occurs exclusively in the urine. Biliary excretion is almost negligible. 2. Di[1-(14)C]ethyltin dichloride has been synthesized. When given intraperitoneally it is excreted in the urine and faeces in the ratio about 1:2. Both the urine and faeces contain ethyltin(3+) and diethyltin(2+). Diethyltin is also excreted extensively in the bile. Di[(14)C]ethyltin is not converted into (14)CO(2) in the rat. 3. About 50% of the injected diethyltin dichloride is de-ethylated to ethyltin(3+). Since ethyltin and diethyltin are found in the urine and faeces after intraperitoneal injection of diethyltin dichloride and since only diethyltin is excreted in the bile, then the de-ethylation of diethyltin occurs in the body tissues and the gut. 4. The conversion of diethyltin into ethyltin has been demonstrated in a preparation of rat caecal contents, but not in liver homogenates. 5. The dealkylation of diethyltin(2+) to ethyltin(3+) in the rat is discussed and it is suggested that the ethyl group is lost as ethane.