An HPLC method for the determination of diclofenac (DCF) and four of i
ts metabolites (3'-hydroxydiclofenac, 4'-hydroxydiclofenac, 5-hydroxyd
iclofenac, and 3'-hydroxy-4'-methoxydiclofenac) in human urine is desc
ribed. Following base hydrolysis, the samples were neutralized and ext
racted. Evaporated extracts were reconstituted in mobile phase contain
ing ascorbic acid, and chromatographed, using flow-rate programming, o
n a reversed-phase column. Absolute recovery (average), was at least 7
8% for diclofenac and ranged from 75 to 85% for the four metabolites.
Standard curves showed linearity over the range of concentrations of 0
.2 to 40 ug/mL, using 0.25 mt of urine. Specificity was demonstrated b
y examining chromatograms of extracts of blank urine from 8 volunteers
and 24 study subjects. Good accuracy was observed for all compounds o
ver the concentration range of 0.2 to 40 ug/mL using 0.25 mt of urine.
Based on accuracy and precision criteria, the limit of quantitation f
or ah 5 analytes was 0.4 ug/mL, using 0.25 mt of urine. Analysis of ur
ine from subjects with normal and reduced renal function who received
diclofenac orally demonstrated that total diclofenac and metabolites e
xcreted in the urine represented approximately 31% and 4% of an oral d
ose of diclofenac, respectively.