 After IM or SC injections, morphine plasma levels peak in approximately 20 min, and, after oral administration, levels peak in approximately 30 min.Morphine is metabolised primarily in the liver and approximately 87% of a dose of morphine is excreted in the urine within 72 h of administration.Morphine is metabolized primarily into morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) via glucuronidation by phase II metabolism enzyme UDP-glucuronosyl transferase-2B7 (UGT2B7).