The formation of 3-MI toxic metabolites in pulmonary cells that leads to AIP is due to intracellular cytochrome P450 (CYP450) enzymes metabolizing 3-MI to 3-methyleneindoline (3-MEIN). Pulmonary pneumocyte CYP450 enzymes can catalyze metabolism of other substrates, one of which is ethyl carbamate . The metabolism of ethyl carbamate in pulmonary cells by CYP450 enzymes produces its toxic metabolites . Its pathogenesis is very similar to 3-MI toxicity .