Determination of the R,R- and S,S-enantiomers of vamicamide in human serum and urine by high-performance liquid chromatography on a Chiral-AGP column.

An enantioselective liquid chromatographic assay for the determinations of the R,R- and S,S-enantiomers of vamicamide, a potent anticholinergic drug, in human serum and urine is described. Racemic vamicamide and internal standard were purified from biological fluids using a two-step extraction procedure involving diethyl ether and 0.1% phosphoric acid. The overall recoveries of racemic vamicamide and internal standard were greater than 80%. The purified samples were measured by high-performance liquid chromatography on a Chiral-AGP column with ultraviolet absorbance detection at 260 nm. The standard curves for the analytes were linear from 10 to 200 ng/ml in serum and from 0.25 to 50 micrograms/ml in urine. The quantification limit of both enantiomers was 10 ng/ml for serum and 250 ng/ml for urine. Both intra-day and inter-day accuracy and precision data showed good reproducibility of the method. The assay has been applied for the analysis of vamicamide enantiomers in serum and urine samples from a healthy volunteer.