Pethidine Medication Description DescriptionPethidine, also known as meperidine and sold under the brand name Demerol among others, is a synthetic opioid pain medication of the phenylpiperidine class. Formula: C15H21NO2 Other names: Meperidine (USAN US) Metabolism: Liver Elimination half-life: 2.5–4 hours, 7–11 hours (liver disease) Dependence liability: High DrugBank: DB00454 Bioavailability: 50–60% (Oral), 80–90% (Oral, in cases of hepatic impairment)