Plasma concentrations of morphine in children with chronic pain--comparison of controlled release and regular...

Comparative plasma concentrations of morphine in two children with chronic pain who received controlled-release and regular morphine sulphate tablets are described. The controlled-release tablets were given every 12 h and regular tablets every 4 h. At steady-state, the maximum morphine plasma concentration (Cmax) was 24.1 ng/ml at 45 mg and 18.7 ng/ml at 30 mg of controlled-release morphine sulphate tablets. The Cmax was 17.6 ng/ml at 15 mg and 31.4 ng/ml at 20 mg dose of the regular tablets. The maximum concentration occurred at 2.0 and 2.5 h after controlled-release and 0.25 and 1.5 h after regular tablets. The minimum morphine plasma concentrations and the area under the plasma concentration-time curve normalized for dose were comparable for the controlled-release and regular tablets. These data indicate that controlled-release morphine sulphate may be well absorbed in relation to the regular tablets. If these results are confirmed in a large group of patients, the controlled-release morphine sulphate tablets may offer a convenient (less frequent) dosing compared with regular tablets in children suffering from chronic pain due to malignancy.