Simultaneous determination of diclofenac sodium and its hydroxy metabolites by capillary column gas chromatography with electron-capture detection.

In humans, diclofenac sodium (Voltaren), a potent anti-inflammatory agent, is metabolized to a large extent by hydroxylation and conjugation to glucuronides and sulfates. This paper describes a procedure whereby unchanged diclofenac as well as all known hydroxylated metabolites (3'-hydroxy-, 4'-hydroxy-, 5-hydroxy- and 4',5-dihydroxy-diclofenac) are determined quantitatively in the same biological sample. The procedure is based on extractive alkylation and gas chromatography with capillary columns and electron capture detection. The method has been applied to analyse urine samples of volunteers treated with single doses of diclofenac sodium.