Plasma pharmacokinetics of morphine after epidural and intermuscular administration in children

ABSTRACT

Morphine concentrations were measured by high performance liquidchromatography with electrochemical detector in plasma of children injectedprior to the operation of hypospadias repair, with morphine sulfate eitherepidurally [50 ug/kg] or intramuscularly [0.1 mg/kg]. After administration,plasma morphine levels began to rise until reached its maximum value after 10min. While in intramuscular administration, the maximum plasma morphinelevels occurred after 5 min. post-injection and a similar disappearance ofplasma morphine was observed and extended for more than 240 min. In a comparison, there is significant decrease in maximum plasma morphine concentration [Cp max], absorption rate constant [Ka], volume of distribution [Vd] and terminal half-life [t 1/2] for children epidurally administered less than intramuscularly administered, while a high significant elevation of timemaximum concentration [t max] was observed in the former route. These datademonstrated the analgesic effectiveness of epidural morphine as compared withintramuscular morphine