Metabolism of haloforms to carbon monoxide. II. In vivo studies.

Administration of haloforms (trihalomethanes) to rats led to substantial elevations in blood carbon monoxide levels. The administration of 13C-bromoform led to the formation of similarly enriched 13CO. A dose-dependent relationship between bromoform dose and CO production was observed. It was found that phenobarbital, but not 3-methylcholanthrene, treatment increased the blood CO levels seen after the administration of bromoform as compared to saline-treated controls. Lower blood CO levels were found in rats given 2H-bromoform as compared to rats given bromoform. Furthermore, SKF 525-A significantly inhibited the in vivo metabolism of bromoform to CO. Administration of either diethyl maleate or D-penicillamine did not alter the blood CO levels produced in response to bromoform administration. The in vivo metabolism of haloforms to CO followed the halide order; thus, administration of iodoform yielded the highest blood CO levels, whereas chloroform yielded the lowest levels.