The cytochrome P450 isoform that is primarily involved in the metabolism of the antipsychotic lurasidone is CYP3A4. Drugs that inhibit or induce this enzyme would then be expected to increase or decrease serum concentrations of lurasidone, respectively. Atazanavir, an HIV-1 protease inhibitor, has demonstrated to be an inhibitor of CYP3A4 and would be expected to increase the exposure of any drug metabolized by this enzyme. We report a case of an atazanavir-precipitated drug–drug interaction that led to elevated serum concentrations of lurasidone and associated clinical symptoms of drug toxicity.
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