Adverse effects of trimethoprim-sulfamethoxazole in a child with dihydropteridine reductase deficiency.

A child with dihydropteridine reductase (DHPR) deficiency developed signs of dopamine insufficiency after being given trimethoprim-sulfamethoxazole (TMP-SMX). She recovered function after the antibiotic was stopped, which suggests that it adversely influenced dopamine metabolism in the CNS. The authors speculate that TMP, a dihydrofolate reductase inhibitor, was the major cause of the patient's deterioration, and suggest that it and other dihydrofolate inhibitors, notably methotrexate, are contra-indicated for patients with DHPR deficiency.