Pethidine is an opioid analgesic. It is regarded as weak opioid and its side-effects profile means that its use is deprecated in favour of using more efficacious opioids. Its dysphoric effects make it a popular request by intravenous drug abusers.
It was traditionally preferred in biliary colic and pancreatitis on the basis of early studies which suggested that it causes significantly less sphincter of Oddi spasm compared to morphine. Subsequent studies have demonstrated that all opioids cause some degree of increased sphincter pressure, including pethidine.
IV IM 50mg qds
Cautions and Interactions
- Seizures in accumulative toxicity . This is thought to due to its metabolite norpethidine which can cause dysphoria and lower seizure threshold. Norpethidine itself has a longer half-life than pethidine itself, which poses a danger of toxicity in repeated use.
- Nausea and vomiting
- Respiratory depression
- Hallucinations & Confusion