Validated UHPLC-MS/MS method for the simultaneous determination of pramipexole and ropinirole in plasma of patients with Parkinson's disease.

A simple and validated ultra high pressure liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of the dopaminergic agents pramipexole and ropinirole in plasma of patients with Parkinson's disease. Following liquid-liquid extraction with tert-butyl methyl ether from 250μL plasma, the separation of the analytes was achieved on a Gemini NX3 column using 10mM pH 6.0 ammonium formate and 10mM ammonium formate in methanol as binary gradient mobile phase at a flow rate of 0.3mL/min. The MS/MS ion transitions were 212.10→153.03 for pramipexole, 261.2→114.2 for ropinirole and 256.1→211 for the internal standard (lamotrigine). The lower limit of quantitation (LLOQ) for both analytes was 80pg/mL and the linearity was determined from 80 to 4000pg/mL for pramipexole and from 200 to 10000pg/mL for ropinirole. Mean recoveries were 94% for PRA and 73% for ROP. Both intra- and inter-assay precision and accuracy were ≤20% at LLOQ concentration and ≤15% at other concentrations. The proposed validated method was successfully applied to measure plasma concentrations of pramipexole and ropinirole in a series of patients with Parkinson's disease on chronic treatment. By grouping the two dopaminergic agents in the same assay, the method allows a large series of patient samples to be processed in a single analytical session.