Absorption:Mean Tmax is 3.7h and mean Cmax is 9.9 to 27.4 ng/mL (dose dependent) for sustained-release form. Bioavailability is approximately 40%.
Distribution:Morphine distributes to skeletal muscle, kidneys, liver, intestinal tract, lungs, spleen, and brain; crosses the placental membrane and is found in breast milk.
Metabolism:Virtually all converted into glucuronide metabolites; small fraction is demethylated in the liver. Major metabolite is morphine-3-glucuronide (55% to 75%).
Elimination:The t½ is approximately 2 to 4 h.
Onset:Onset is 15 to 60 min (intrathecal/epidural).
Duration:Duration is 3 to 7 h.
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