RESUMEN
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