Clinical analysis of tamoxifen, an anti-neoplastic agent, in plasma

Tamoxifen, a phenylstilbene derivative, is currently being used to treat metastatic breast cancer. We describe an analytical method for monitoring the parent drug and its 4-hydroxylated derivative in whole blood and plasma. After extraction from biological media, the analytes are converted to highly fluorescent products by ultraviolet irradiation, and then separated by liquid-chromatography on a muBondapak CN column, with spectrofluorometric detection of components. Detection limits for tamoxifen and its 4-hydroxy derivative are 1 and 2 microgram/liter of biological fluid, respectively. Conditions have been optimized so that the reaction proceeds fast enough for convenient sample handling without jeopardizing fluorescence yield due to the photocatalyzed degradation of the fluorescent product. Evidence suggests that the fluorophore being monitored is a phenanthrene derivative.