PHARMACOKINETICS OF MORICIZINE IN YOUNG-PATIENTS

Moricizine is a novel phenothiazine antiarrhythmic agent that depresse s the activity of ectopic foci, has a low incidence of adverse effects relative to other agents, and is useful in treating pediatric atrial ectopic tachycardia. A study was conducted to determine the pharmacoki netics of moricizine in children after oral administration. Moricizine was isolated from frozen serum obtained from four male patients (ages 7, 8, 9, and 18 years) receiving the drug for supraventricular tachyc ardia and analyzed by high-performance liquid chromatography with ultr aviolet detection according to an established protocol. Peak serum lev els were between 400 and 2000 ng/mL. Elimination of moricizine did not follow simple single-compartment pharmacokinetics. In three patients we observed an increase or slower decline in blood level occurring aft er 4 hours. Because of the paroxysmal nature of the tachycardias, decr eases in patient heart rate could not be correlated with moricizine bl ood level. These results suggest that the pediatric pharmacokinetics o f moricizine excretion are complex and may differ from those seen in a dults.