Dopamine Adjustment Difficulties in Special Pathophysiological Conditions
Abstract
Dopamine is a commonly used drug but its biology and cellular action is not well known, its bizarre actions in neonates back to different pattern of receptors on vascular and metabolic excretion rate especially in preterm babies.[1] Dopamine’s physiological action is dose dependent and give maximum diuresis and natriuresis at the dose of 2 micrograms/kg/min compared to 4 micrograms/ kg/min in neonates.[2] Such physiological properties back to immature norepinephrine stores that halt inotropic effects and longer elimination half time related to age that accentuate side effects of dopamine such as tachycardia.[3] Such side effects may accentuate in renal and hepatic deficiency because of lower clearance of dopamine and risk of toxicities in usual doses administration.[4] The other challenging factor for easy administration of dopamine is various inter individual pharmacokinetics property of dopamine especially in seriously ill patients.[5] Cochran study in small sample of selected asphyxiated neonate cases showed low dose dopamine as low as 2.5 micrograms/kg/min cannot decrease mortality and morbidity compared to placebo[6] and doses as low as 7 micrograms/kg/min make pulmonary vasoconstriction in critically ill case and infusion rate of 5 micrograms/kg/min cannot bring target hemodynamic indices in a great proportion of patients (9 of 25) inspite of tachycardia occurred in them as a side effect without increase in stroke volume and modest reduction in systemic vascular resistance.[7-8] Dopamine, efficacy, decrement during lactic acidosis is another challenge in spite of the plasma norepinephrine level was elevated dramatically during severe lactic acid acidosis in compared to normal acidosis.[9]
