SFC-MS/MS method for simultaneous determination of nimodipine and 3-n-butylphthalide in beagle plasma: application to pharmacokinetic interaction study.

Aim: Nimodipine and 3-n-butylphthalide are co-administered to treat vascular dementia, but the pharmacokinetic interaction between the two drugs is still unknown. Therefore, a robust, high-throughput and economical supercritical fluid chromatography-ESI-MS/MS method has been initially developed to simultaneously determine nimodipine and 3-n-butylphthalide in beagle plasma, in order to study the safety of co-administration. Materials & methods: After a simple protein precipitation procedure, isocratic elution with mobile phase of CO2 and methanol (containing 0.3% formic acid and 2 mM ammonium acetate) was applied to minimize run time and facilitate sensitive and high-throughput bioanalysis. The method was fully validated according to US FDA Guidance. The validated method was then successfully applied in a pharmacokinetic interaction study. Results: The results indicated there is no significant pharmacokinetic interaction between the two drugs.