Pharmacokinetics of morphine in cerebrospinal fluid and plasma after epidural administration in man.

The morphine concentration in serum as well as in cerebrospinal fluid (CSF) after epidural administration of 0.1 mg/kg morphine to 10 patients undergoing aortic abdominal surgery, was determined. Model independent pharmacokinetic parameters in serum and CSF i.e. mean residence time (MRT), clearance (Cl) and apparent volume of distribution were calculated from the concentration time curves using a non-linear square regression fitting programme. Peak concentration of morphine in serum (86 ng/ml) and in CSF (2610 ng/ml) was reached after 10 min respectively 40 min of epidural injection.