Determination of the anti-inflammatory agent carprofen, (D,L)-6-chloro-alpha-methylcarbazole-2-acetic acid, in blood by high-pressure liquid chromatography.

A rapid, sensitive, and specific high-pressure liquid chromatographic (HPLC) assay was developed for the determination of (D,L)-6-chloro-alpha-methylcarbazole-2-acetic acid (carprofen) in blood. The assay involves extraction into diethyl ether from blood buffered to pH 6. The overall recovery of carprofen from blood is 97.3 +/- 5.3% (S.D.), and the sensitivity limit of detection is 100-200 ng/ml of blood using a fluorescence detector with excitation at 240 nm and emission at wavelengths greater than 350 nm. The HPLC assay is amenable to rapid routine analysis of clinical specimens, and the data obtained using this assay showed an excellent correlation coefficient (0.99) compared with a previously published spectrofluorometric assay. The method was used to monitor the blood level-time fall-off profiles in four subjects following single and multiple dose administration of carprofen.