Abstracts

Therapeutic Drug Monitoring (TDM) of anticonvulsants is an important tool in the management of patients with epilepsy. An analytical method has been developed which enables the simultaneous quantitation of 14 different antiepileptic compounds by high performance liquid chromatography electrospray ionization tandem mass spectrometry (LC/MS/MS) from dried capillary blood spots that are collected on filter paper. This collection method allows samples to be obtained by relatively untrained caregivers or patients at critical time points, eliminating the need for phlebotomy. Two 3/16 inch saturated filter paper circles are punched and the sample is resolubilized into a solution of acetonitrile and water. Chromatographic resolution is obtained using standard reverse phase liquid chromatography. Analytes are detected and quantified by monitoring their specific molecular fragmentation reactions on a triple quadrupole mass spectrometer. The complete panel of analytes are assayed as two separate injections of the extract, one in negative ionization mode and one in positive ionization mode. Run time for each injection is approximately 3.5 minutes. Characteristics of the method are presented in Table 1. [table1] This analytical methodology provides a full spectrum, precise analysis of commonly prescribed anticonvulsants across typical therapeutic ranges. The collection of capillary blood spots on filter paper is minimally invasive, easy to perform, and temporally relevant. The ability of patients and caregivers to collect capillary samples in close proximity to an ictal or a toxic event without the need to find phlebotomy services not only reduces patient perceived inconvenience of performing TDM testing, but also increases the amount of useful information obtained by providing the physician with precise drug levels at time points most critical to managing an individual[apos]s epilepsy. (Supported by MEDTOX Laboratories, Inc.)