Convulsions from excessive dosage of nalidixic acid: a case report.

A 4-year-old girl who developed convulsions after an accidental ingestion of excessive dosage (50 mg/kg) of nalidixic acid, while treated with the drug (50 mg/kg/day) over 30 days for a urinary tract infection, was reported. Thirty minutes after ingestion, vomiting, tonic-clonic seizures, and abnormal movements were supervened. After ninety minutes, the serum levels of nalidixic acid and hydroxynalidixic acid were 146.1 and 48.9 microgram/ml, respectively. In controls, the mean levels of nalidixic acid and hydroxynalidixic acid were 7.8 +/- 6.8 (SD) and 3.02 +/- 2.6 microgram/ml, respectively.