 This can also allow lower total doses in some such people.The analgesic activity is shorter than the pharmacological half-life; dosing for pain control usually requires multiple doses per day normally dividing daily dosage for administration at 8 hour intervals.The main metabolic pathway involves "N"-demethylation by CYP3A4 in the liver and intestine to give 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP).