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The pharmacokinetics of oxypurinol in people with gout
Author(s) -
Stocker Sophie L.,
McLachlan Andrew J.,
Savic Radojka M.,
Kirkpatrick Carl M.,
Graham Garry G.,
Williams Kenneth M.,
Day Richard O.
Publication year - 2012
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.2012.04207.x
Subject(s) - probenecid , allopurinol , pharmacokinetics , gout , pharmacology , medicine , renal function , dosing , concomitant , hyperuricemia , uric acid
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Response to allopurinol in patients with gout is often suboptimal due to large variability in pharmacokinetics. • The sources of the variability in oxypurinol pharmacokinetics have not been systematically identified and quantified. • A therapeutic target 15–23 mg l −1 for oxypurinol concentrations has recently been established. WHAT THIS STUDY ADDS • Renal function and concomitant diuretic/probenecid use significantly influence oxypurinol pharmacokinetics. • This model provides a tool to achieve target oxypurinol plasma concentrations, thereby optimizing the effectiveness and safety of allopurinol therapy in gouty patients with various degrees of renal impairment. • Model predictions show a failure to reach target oxypurinol concentrations using suggested allopurinol dosing guidelines. AIMS Our aim was to identify and quantify the sources of variability in oxypurinol pharmacokinetics and explore relationships with plasma urate concentrations. METHODS Non‐linear mixed effects modelling was applied to concentration–time data from 155 gouty patients with demographic, medical history and renal transporter genotype information. RESULTS A one compartment pharmacokinetic model with first order absorption best described the oxypurinol concentration–time data. Renal function and concomitant medicines (diuretics and probenecid), but not transporter genotype, significantly influenced oxypurinol pharmacokinetics and reduced the between subject variability in the apparent clearance of oxypurinol (CL/ F m ) from 65% to 29%. CL/ F m for patients with normal, mild, moderate and severe renal impairment was 1.8, 0.6, 0.3 and 0.18 l h −1 , respectively. Model predictions showed a relationship between plasma oxypurinol and urate concentrations and failure to reach target oxypurinol concentrations using suggested allopurinol dosing guidelines. CONCLUSIONS In conclusion, this first established pharmacokinetic model provides a tool to achieve target oxypurinol plasma concentrations, thereby optimizing the effectiveness and safety of allopurinol therapy in gouty patients with various degrees of renal impairment.