Metabolic disposition of methyldopa in hypertensive and renal-insufficient children.

The serum levels of methyldopa and its principle metabolites were assessed in 22 hypertensive children, of whom 13 had impaired renal function. A significant correlation was found between the magnitude of the renal dysfunction and the serum levels of methyldopa, alpha-methyldopa-sulfate, alpha-methyldopamine, and alpha-methyldopamine-sulfate. The patients were divided into 2 groups: those with normal (serum creatinine less than or equal to 1.0 mg/100 ml) and those with abnormal (serum creatinine greater than 1.0 mg/100 ml) renal function. The serum level of alpha-methyldopa-sulfate and not of methyldopa was elevated in those with renal dysfunction. The serum levels of alpha-methyldopamine and, in particular, its 3-0 sulfate conjugate were markedly elevated in patients with renal disease. These data suggest that the enhanced sensitivity to methyldopa in patients with impaired renal function may be due in part to alpha-methyldopamine.