Objective: The present study was undertaken to investigate the pharmacokinetics (PKs) of gabapentin as determined by traditional manual blood sampling and by using an automated dosing/blood sampling technique in awake and freely moving rats using combined liquid chromatography tandem mass-spectrometry (LC-MS/MS).
Materials and methods: PK comparisons were conducted by allocating rats into two groups; an automated dosing/blood sampling (ADI/ABS) group (IV study, n = 6 and intragastric study, n = 6) and a manual group (IV study, n = 6 and oral study, n = 6). A series of blood samples from carotid artery were taken at specified times and analyzed using a validated LC-MS/MS method. Various PK parameters like area under curve (AUC(inf)), maximum concentration, time to reach maximum concentration, terminal half life, distribution volume at the steady state, and total clearance were calculated and the two study groups were compared with respect to these parameters.
Results: Significant differences in PK parameters were observed between the manual group and the ADI/ABS group and respective bioavailability were measured (46.82 ± 19.45% and 61.54 ± 21.23%, respectively) which is 1.31-fold difference (P = 0.0051, P<0.05).
Conclusion: The described ADI/ABS method was found to be a useful drug development tool for accelerating the pace of preclinical in vivo studies and for obtaining reliable and accurate PK parameters even from single animals as it minimized interanimal and physiological variations.
Keywords: Automated dosing/blood sampling; LC-MS/MS; gabapentin; pharmacokinetics.