Dopamine Infusion in Man. Plasma Catecholamine Levels and Pharmacokinetics

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Abstract
Dopamine is widely used in the treatment of hypotensive conditions and/or impending renal failure, but the plasma levels of dopamine and other catecholamines in association with dopamine infusion are unknown. Plasma catecholamines and dopamine pharmacokinetics during and after dopamine infusion were studied in man. Two and 5 .mu.g/kg min of dopamine were infused for 30 min in 2 groups of 5 patients. Dose-dependent mean steady state levels with fairly large interindividual variations were reached within 5 min. Elimination of dopamine from plasma after termination of infusion had a biphasic course with t1/2 .alpha. [elimination half-life] around 1 min and t1/2 .beta. .apprx. 9 min in both groups. Noradrenaline [norepinephrine] plasma levels and blood pressure increased significantly in the 5 .mu.g group. Vasoconstriction with deleterious effects on tissue perfusion, seen in conjunction with high-dose dopamine infusion, may be due to increased noradrenaline levels.