Development and validation of a highly sensitive gradient chiral separation of pramipexole in human plasma by LC-MS/MS

Development of a high-sensitivity chiral LC-MS/MS method was required to evaluate a combination of pramipexole ( -PPX) and its enantiomer dexpramipexole ( -PPX) in a proposed clinical trial. The previously available methods suffered from low sensitivity for the ( )-enantiomer in the presence of the more abundant ( )-enantiomer. Based on the projected dosing regimen in the clinical trial, a 5000-fold improvement in sensitivity was required for the ( )-enantiomer. : Spiked human plasma samples were extracted by liquid-liquid extraction using ethyl acetate and injected onto a CHIRALPAK ID column under pH gradient conditions. An improved analytical method was developed and validated with a final LLQ for ( )-PPX of 0.1 ng/ml in the presence of 2000 ng/ml of ( )-PPX.