High performance liquid chromatography coupled with mass spectrometry for simultaneous determination of rivastigmine and its metabolite in rat plasma

Several studies on the pharmacokinetic parameters of antidementia drugs have reported that plasma concentration is linked to the drugs' efficacy and adverse effects. At present, there is no quantitation method that is highly sensitive and can be applied to simultaneous monitoring of the pharmacokinetics of rivastigmine and its metabolites (NAP 226-90) in rat plasma. No methods fulfilling the assay validation requirements of the US Food and Drug Administration and the European Medicines Agency was also established. Therefore, this study developed a quantitative method for measuring rivastigmine and NAP 226-90 concentrations using high-performance liquid chromatography and tandem mass spectrometry, examining plasma samples after rivastigmine administration. Rat plasma samples were pre-pared via the protein precipitation method. The methods for measuring rivastigmine and NAP 226-90 concentrations showed good fit over wide ranges of 1-100 ng mL(-1) and 0.5-50 ng mL(-1), with lower limits of quantification at 1 ng mL(-1 )and 0.5 ng mL(-1), respectively. The plasma concentrations of rivastigmine and NAP 226-90 in six healthy rats were successfully determined, demonstrating the feasibility of applying the developed method. Thus, this research has successfully developed a sensitive, selective method, to simultaneously quantify rivastigmine and NAP 226-90 concentrations in rat plasma and be applicable to a pharmacokinetic study.