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Biased estimates of nonrenal clearance
1Department of Clinical Pharmacology, Berlex Laboratories, Inc., 300 Changebridge Road, P.O. Box 1000, Montville, New Jersey 07045-1000, USA. peter_hinderling@berlex.com
Journal of Pharmaceutical Sciences
|July 18, 2001
Summary
Published oral nonrenal clearance values often overestimate true drug clearance. This systematic bias, influenced by bioavailability and renal function, can lead to false conclusions about drug metabolism in patients with kidney impairment.
Area of Science:
- Pharmacokinetics
- Drug Metabolism
- Renal Function Assessment
Background:
- Accurate assessment of drug clearance is crucial for effective dosing.
- Oral nonrenal clearance is a key parameter in pharmacokinetic studies.
- Existing methods for estimating oral nonrenal clearance may be flawed.
Purpose of the Study:
- To critically evaluate published oral nonrenal clearance values.
- To assess the dependence of oral nonrenal clearance on renal function.
- To identify potential overestimation in current estimation methods.
Main Methods:
- Derivation of pharmacokinetic equations.
- Computational analysis of drug clearance data.
- Evaluation of varying renal function and bioavailability.
Main Results:
- Published oral nonrenal clearance values systematically overestimate true oral and intravenous nonrenal clearances.
- This overestimation occurs in subjects with both normal and impaired renal function.
- The bias is most significant for renally excreted drugs with low bioavailability.
Conclusions:
- Apparent oral nonrenal clearance values can lead to misinterpretation of drug metabolism.
- A false diagnosis of decreased nonrenal clearance may occur in renal impairment.
- Bioavailability and renal clearance significantly impact the accuracy of oral clearance estimates.