Exacerbation of porphyria during treatment of pulmonary tuberculosis.

Several attacks of acute intermittent porphyria complicated the treatment of a patient with pulmonary tuberculosis. To determine whether the attacks were drug-induced, the ability of a variety of antituberculous drugs to induce (delta)-amino-levulinic acid synthetase activity in a rat liver model was assessed. Pyrazinamide was found to be capable of significantly inducing amino-levulinic acid synthetase activity; the other antituberculous drugs caused either slight or no induction of amino-levulinic acid synthetase. The data suggest that pyrazinamide was capable of causing an exacerbation of the patient's porphyria. Tuberculosis, by causing debility, may also have aggravated this patient's previously latent porphyria.