Determinants of the diuretic response to furosemide in infants with congestive heart failure.

A wide interindividual variation in the degree of diuresis produced following treatment with furosemide has been observed in infants with congestive heart failure. A method of pharmacokinetic analysis that separates drug disposition from renal response to furosemide was used to compare the effect of this agent in infants with congestive heart failure with the effect seen in infants with fluid retention secondary to noncardiac factors. No differences in the drug elimination rate, urinary drug excretion, or renal diuretic response between the 2 groups were seen. Infants in both groups exhibited a wide range in all variables examined. The marked interindividual variation in response originates from decreased delivery of furosemide to its site of action in some patients and a decreased responsiveness to the drug in others.