Rapid determination of plasma vigabatrin by LC-ESI-MS/MS supporting therapeutic drug monitoring in children with infantile spasms.

Vigabatrin is one of the second-generation anti-seizure medications (ASMs) designated orphan drugs by the FDA for monotherapy for pediatric patients with infantile spasms from 1 month to 2 years of age. Vigabatrin is also indicated as the adjunctive therapy for adults and pediatric patients 10 years of age and older with refractory complex partial seizures. Ideally, the vigabatrin treatment entails achieving complete seizure freedom without significant adverse effects, and the therapeutic drug monitoring (TDM) will make a significant contribution to this aim, which provides a pragmatic approach to such epilepsy care in that the dose tailoring can be undertaken for uncontrollable seizures and in cases of clinical toxicity guided by the drug concentrations. Thus, reliable assays are mandatory for TDM to be valuable, and blood, plasma, or serum are the matrixes of choice. In this study, a simple, rapid, and sensitive LC-ESI-MS/MS method for the measurement of plasma vigabatrin was developed and validated. The sample clean-up was performed by an easy-to-use method, i.e., protein precipitation using acetonitrile (ACN). Chromatographic separation of vigabatrin and vigabatrin-13C,d2 (internal standard) was achieved on the Waters symmetry C18 column (4.6 mm × 50 mm, 3.5 µm) with isocratic elution at a flow rate of 0.35 mL min-1. The target analyte was completely separated by elution with a highly aqueous mobile phase for 5 min, without any endogenous interference. The method showed good linearity over the 0.010-50.0 µg mL-1 concentration range with a correlation coefficient r2 = 0.9982. The intra-batch and inter-batch precision and accuracy, recovery, and stability of the method were all within the acceptable parameters. Moreover, the method was successfully used in pediatric patients treated with vigabatrin and also provided valuable information for clinicians by monitoring plasma vigabatrin levels in our hospital.