The bioavailability and pharmacokinetics of morphine after intravenous, oral and buccal administration in healthy volunteers.
1. The absolute bioavailability of morphine from oral aqueous solution, a controlled release oral tablet (MST-Continus) and a controlled release buccal tablet has been investigated in six healthy volunteers. 2. Analysis of plasma samples for morphine and its active metabolite morphine-6-glucuronide (M6G) was by means of a differential radioimmunoassay technique. Absolute bioavailability for morphine was estimated to be 23.9% after oral solution, 22.4% after MST-Continus and 18.7% after the buccal tablet. Maximum plasma morphine concentrations were seen at 45 min (oral solution), 2.5 h (MST) and 6 h (buccal). 3. There was no difference in the amount of M6G appearing in plasma after intravenous, oral or buccal administration but the mean ratio of AUCs for M6G: morphine in plasma after intravenous morphine was 2 : 1 compared with 11 : 1 after oral and buccal morphine.
Hoskin
P J
PJ
Continuing Care Unit, Royal Marsden Hospital, Sutton, Surrey.
Hanks
G W
GW
Aherne
G W
GW
Chapman
D
D
Littleton
P
P
Filshie
J
J
D000278:Administration, Buccal; D000284:Administration, Oral; D000328:Adult; D001682:Biological Availability; D001711:Biotransformation; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D011863:Radioimmunoassay
D009020:Morphine