Meperidine (Pethidine) is a fast-acting opioid analgesic drug. Meperidine is indicated for the treatment of moderate to severe pain, and is delivered as its hydrochloride salt in tablets, as a syrup, or by intramuscular or intravenous injection. It was synthesized in 1939 as an antimuscarinic agent(13). Meperidine exerts its analgesic effects by the same mechanism as morphine, by acting as an agonist at the ?-opioid receptor. Like other opioid drugs, meperidine has the potential to cause physical dependence or addiction. In addition to the adverse effects common to all opioids, such as constipation, dry mouth, light-headedness, twitchiness, muscular twitches, and nausea, the repeated administration of meperidine can lead to neurotoxic effects.