Systemic availability of oral slow-release morphine in man.
In a within-patient crossover study on twelve patients we investigated plasma morphine concentrations for 48 hours after administration of intravenous morphine sulphate followed 24 hours later by oral MST Continus [MST]. Patients received either 10 mg i.v. morphine followed by 10 mg MST or 20 mg i.v. morphine followed by 2 X 10 mg MST tablets. Systemic clearance of morphine was low, being about 3 ml/min/kg after both intravenous and oral administration. The ratio of the areas under the concentration-time curve for MST relative to that for i.v. morphine was about 1:1 for 20 mg doses, but was significantly greater than 1:1 for 10 mg doses. The results suggest high oral systemic availability for morphine and low hepatic morphine metabolism.
D000284:Administration, Oral; D001682:Biological Availability; D003692:Delayed-Action Preparations; D006801:Humans; D007275:Injections, Intravenous; D008099:Liver / Q000378:metabolism; D009020:Morphine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D010146:Pain / Q000188:drug therapy
D003692:Delayed-Action Preparations; D009020:Morphine