This application note presents the automated determination of carbamazepine, its metabolite carbamazepine-10,11-epoxide and gabapentin in dried blood spots (DBS) using the GERSTEL Dried Blood Spot Autosampler (DBS-A) coupled online to LC-MS/MS. The analysis method was employed to demonstrate the feasibility of pharmacokinetic studies with this type of instrumentation. Concentration vs. time curves were recorded for the analytes in real dried blood samples from a volunteer person after application of a single oral dose of each drug. Data generated were in agreement with pharmacokinetic data from scientific literature.
In the context of this application a novel DBS sampling device - HemaXis DB - for simplified collection of volumetric DBS by minimally trained users was employed. The sampling system proved reliable and delivered good precision. Relative standard deviations for repeat analyses after sampling of real blood with HemaXis DB were between 3.1 and 11% for the target compounds. Manual pipetting of spiked whole blood onto DBS cards and subsequent analysis resulted in similar relative standard deviations. Limits of quantification (LOQ) were estimated as 8 ng/mL for carbamazepine, 4 ng/mL for carbamazepine-10,11-epoxide, the major carbamazepine metabolite, and 2 ng/mL for gabapentin, respectively.
The GERSTEL Dried Blood Spot Autosampler (DBS-A) and the HemaXis DB device were found to be valuable tools for pharmacokinetic studies, helping to reduce cost of sampling and sample shipment while improving data quality since repeat or more frequent blood sampling is feasible without the need for healthcare professionals to perform the sampling.
Pharmacokinetic study on carbamazepine and gabapentin employing HemaXis DB, a novel device for convenient whole blood self-sampling, and the GERSTEL Dried Blood Spot Autosampler (DBS-A) coupled online to LC-MS/MS