RAPID, SOLID-PHASE EXTRACTION TECHNIQUE FOR THE HIGH-THROUGHPUT ASSAYOF DARIFENACIN IN HUMAN PLASMA

A novel method has been developed for the rapid solid phase extraction of drugs and metabolites from biological fluids, prior to further ana lysis. The newly designed, 96-tube micropreparation block facilitates high throughput by enabling the extraction of 96 samples simultaneousl y. The system is described, linked to HPLC/APCI-MS/MS, for the determi nation of darifenacin in human plasma. The resulting procedure, using deuterated darifenacin as internal standard, is validated over the con centration range 25-2000 pg/mL; accuracy (0.6-4.6%) and precision (3.6 -18.8%) are considered acceptable and overall recovery was determined to be similar to 50%.