A 50-year-old man is brought to the emergency department by ambulance. His respirations are shallow and infrequent, his pupils are constricted, and he is stuporous. He was noted to have suffered a grandmal seizure in the ambulance. Which of the following drugs is this man likely to have overdosed on?

Severe opiate intoxication is associated with respiratory depression, stupor or coma, and sometimes pulmonary edema. Less severe intoxication is associated with slurred speech; drowsiness, and impaired memory or attention. Early on, the pupils are constricted, but they dilate if the patient becomes 'anoxic due to the respiratory depression. BP is typically. Meperidine intoxication in a chronic user is often complicated by delirium or seizures due to the accumulation of nor meperidine, a toxic metabolite with cerebral irritant properties.