Seizures Reported With Tramadol

To the Editor. —Tramadol hydrochloride (Ultram, McNeil Pharmaceutical, Spring House, Pa) is a centrally acting, synthetic, opioid analgesic that was approved for marketing in the United States in March 1995 for the treatment of moderate to moderately severe pain. The recommended adult dosage is 50 mg to 100 mg every 4 to 6 hours, not to exceed 400 mg/d.1 Within the first year after marketing approval in the United States, the Food and Drug Administration (FDA) received 83 reports of seizures among patients using tramadol. This led to labeling changes and issuance of a "Dear Doctor" letter.2During tramadol's second year on the market, the FDA received more than 200 reports of seizures. We describe the clinical features of seizure cases reported for tramadol. From the FDA's database of adverse drug events,3we retrieved all domestic US reports for tramadol coded for seizures that the FDA had