Renal dose dopamine does not alter the response to beta-adrenergic stimulation by isoproterenol in healthy human volunteers

Comparison of Systemic and Renal Effects of Dopexamine and Dopamine in Norepinephrine-Treated Septic Shock

OBJECTIVES

Vasopressor-induced vasoconstriction may compromise renal and splanchnic blood flow in patients with septic shock, resulting in secondary organ failures. The authors compared the effects of the vasodilatatory agent dopexamine against renal-dose dopamine and placebo in patients with norepinephrine therapy and septic shock, using 24-hour serum creatinine clearance (C(crea)) as a major endpoint. The primary hypothesis to be tested was that dopexamine is more effective than dopamine and that dopamine shows better effects than placebo regarding organ failures and C(crea).

DESIGN

A prospective, randomized, controlled, double-blinded study.

SETTING

Intensive care unit in a tertiary care university hospital.

PARTICIPANTS

Sixty-one patients with septic shock defined according to established criteria.

INTERVENTIONS

Patients received either dopexamine (2 microg/kg/min, n = 20), dopamine (3 microg/kg/min, n = 21), or placebo (n = 20).

RESULTS

The trial groups were similar in terms of baseline characteristics. The authors found no significant differences among the dopexamine, dopamine, and placebo groups with regard to a comprehensive number of renal function parameters including C(crea) and organ-failure scores. There was a significant increase in heart rate after dopexamine infusion; other hemodynamic parameters remained unchanged in the dopexamine group. In a post hoc analysis that included only patients with renal impairment at study inclusion (n = 28), patients who received dopamine showed significant improvements in C(crea) when compared with placebo. Dopexamine was not effective in this subgroup.

CONCLUSIONS

Dopexamine is no more effective than dopamine or placebo regarding renal function in patients with septic shock requiring norepinephrine. Both therapies do not influence organ-failure scores.

Fenoldopam mesylate and renal function in patients undergoing liver transplantation: a randomized, controlled pilot trial

To test the relative effects on serum creatinine (CRE), blood urea nitrogen (BUN), and urine output of small-dose dopamine and fenoldopam in patients undergoing liver transplantation, we randomized 43 patients to 1 of 2 continuous infusions over 48 h, starting with anesthesia induction: fenoldopam, 0.1 microg . kg(-1) . min(-1) or dopamine, 2 microg . kg(-1) . min(-1). We used predetermined hemodynamic and intravascular volume goals (intrathoracic blood volume index 800-1000 mL/m(2), extravascular lung water index <7 mL/kg) to manage patients with an algorithm for use of mannitol and furosemide to maintain urine output >1 mL . kg(-1) . h(-1). At postoperative day 3, the median CRE increase was 0.2 mg/dL (interquartile range [IQR] -0.2-0.5) with fenoldopam and 0.5 mg/dL (IQR 0.3-0.9, P = 0.004) in the dopamine group. The BUN increase was median 2 mg/dL (IQR -2-8) versus 8.5 mg/dL (IQR 5-12, P = 0.01), respectively, with fenoldopam versus dopamine. Urine output was similar; however, significantly fewer fenoldopam patients required furosemide compared with dopamine patients (median 1 [IQR 0-3] versus 3 [IQR 2-4], respectively, P = 0.003). The hemodynamic effects of dopamine and fenoldopam were similar. Compared with dopamine, in the setting of liver transplantation, fenoldopam is associated with better CRE and BUN values.

The therapeutic potential of dopamine modulators on the cardiovascular and renal systems

In the periphery, physiological dopamine increases renal blood flow, decreases renal resistance and acts on the kidney tubule to enhance natriuresis and diuresis. The loss of dopamine function may be involoved in the deterioration in kidney function associated with ageing and may have a role in the pathogenesis of hypertension and diabetes. Intravenous dopamine is used as a positive inotrope in the treatment of acute heart failure and cardiogenic shock and as a diuretic in renal failure. The clinical uses of dopamine are limited, as it must be given intravenously, and also has widespread effects. The levels of peripheral dopamine can be increased by the administration of L-dopa to increase synthesis, prodrugs to release dopamine (docarpamine, glu-dopa) or by inhibiting the breakdown of dopamine (nitecapone). Preliminary clinical trials suggest that docarpamine may be useful in patients with low cardiac output syndrome after cardiac surgery and in refractory cirrhotic ascites. Ibopamine is an agonist at dopamine D1 and D2 receptors, which may retard the progression of chronic renal failure. Glu-dopa is selective for the kidney, thus avoiding widespread side effects. The early clinical studies with ibopamine as a diuretic in heart failure were favourable but the subsequent large mortality study showed that ibopamine increased mortality. Fenoldopam is a selective dopamine D1 receptor agonist. Intravenous fenoldopam may be useful in the treatment of hypertension associated with coronary artery bypass surgery or in hypertensive emergencies. Although our understanding of physiological and pathological roles of peripheral dopamine has been increasing rapidly in recent times, we still need more information to allow the design of clinically useful drugs that modify these roles. One priority is an orally-active selective dopamine D1 receptor agonist.