Determination of thalidomide in plasma and blood by high-performance liquid chromatography: avoiding hydrolytic degradation.

Thalidomide was determined in plasma and blood by reversed-phase high-performance liquid chromatography with ultraviolet detection. The coefficient of variation of the assay was 1-2% over the 0.25-4.0 micrograms/ml concentration range. Hydrolysis of thalidomide during storage and work-up of the samples was avoided by the addition of an equal volume of citrate buffer, pH 1.5. The assay could be applied to the determination of blood concentrations of thalidomide in rats for at least 28 h after a single oral dose, with multiple blood sampling from the same animal.