Plasma concentration and acute clinical effects of docarpamine, orally active dopamine prodrug, in infants.

Currently, there are no data available on the optimal doses and efficacy of docarpamine in infants. In the present study, three doses of docarpamine, 15.0-20.4 (19.0 +/- 1.9; mean +/- SD) mg/kg per dose every 8 h to 10 infants suffering heart failure. Age and bodyweight were from 1 to 4 (1.4 +/- 1) months and 2960-5160 (3350 +/- 872) g, respectively. In all infants, plasma concentrations of free dopamine were measured 1, 2 and 3 h after the first administration. Heart rate and systolic blood pressure were examined before and at the same time as the first administration. In seven infants, the 24 h urinary output and urinary excretion of electrolytes and creatinine before and during docarpamine were measured. Peak plasma concentration of free dopamine (ng/mL) was achieved after 1 or 2 h of administration, 0-163.1 (37.9 +/- 47.2) and 0-105.0 (37.8 +/- 39.3), respectively. The concentration had decreased rapidly by 3 h to 0-34.2 (12.4 +/- 11.0). Both heart rate (b.p.m.) and blood pressure (mmHg) tended to increase from 120-154 (140 +/- 15) and 56-90 (76 +/- 11) to a peak of 124-162 (148 +/- 14) and 70-92 (79 +/- 8), respectively (P = 0.197, P = 0.289). There were no significant changes in urinary output or excreta. Oral docarpamine of 15-20 mg/kg per dose can achieve plasma free concentrations of dopamine that increase heart rate and systolic blood pressure.