Effect of docarpamine, a novel orally active dopamine prodrug, on the formation of free and sulfoconjugated dopamine in patients who underwent cardiac surgery.
To evaluate the clinical efficacy of orally active dopamine prodrug, docarpamine [N-(N-acetyl-L-methionyl)-O,O-bis (ethoxycarbonyl) dopamine], we examined its effect on the formation of free and sulfoconjugated dopamine in patients who underwent cardiac surgery. The preoperative values of free and sulfoconjugated dopamine in patients were 216 +/- 52 pg/ml and 4,930 +/- 820 pg/ml, respectively. The plasma level of free dopamine increased to 95.3 +/- 28.3 ng/ml by dopamine infusion after the operation and was sustained at a high level (87.7 +/- 26.5 ng/ml) by concomitant administration of docarpamine in spite of tapering of dopamine infusion. After stopping dopamine infusion, plasma level of free dopamine was 24.5 +/- 17.6 ng/ml maintained by oral administration of docarpamine alone. From these results, docarpamine may be a useful alternative to intravenous dopamine after cardiac surgery. Sulfoconjugated dopamine in plasma increased to 267 +/- 120 ng/ml after the start of dopamine infusion and increased further after oral docarpamine administration to 2,060 +/- 610 ng/ml. Since sulfoconjugated dopamine is thought to be a possible precursor of active free dopamine in plasma, orally administered docarpamine might be stored as a reserve pool for free dopamine in patients who undergo cardiac surgery.