Limitations on the physiologic interpretation of aminoglycoside body clearance derived from pharmacokinetic studies.

The interpretation of drug clearances derived from plasma pharmacokinetic analysis must take into account the specific physiologic limitations of this method. For aminoglycosides, this includes an insensitivity of total body clearance (C1B), calculated from plasma data alone, to post-filtration proximal renal tubular sequestration of drug. Only clearances utilizing urine excretion data will detect this event. Secondly, the interpretation of plasma and urine drug clearance data must assess the filterability of aminoglycosides at the glomerulus if correct inferences about the extent of tubular reabsorption are to be made.