Enhancement of dichloromethane-induced carboxyhemoglobinemia by isoniazid pretreatment.

Pretreatment of rats with isoniazid (8 x 0.36 mmol/kg i.p. or 1 x 0.36 mmol/kg i.p.) produced dichloromethane-induced carboxyhemoglobin concentrations in the blood which are 2.6 and 1.8 times higher than carboxyhemoglobinemia after administration of dichloromethane per se. Simultaneous administration of both compounds reduced the dichloromethane metabolism to carbon monoxide as measured by carboxyhemoglobin level in the blood.