Mohamed D.Hegazy M.A.Elshahed M.S.Toubar S.S.Helmy M.I.Analytical Chemistry DepartmentFaculty of PharmacyHelwan UniversityCairoEgypt; Pharmaceutical Analytical Chemistry DepartmentFaculty of PharmacyOctober University for Modern Sciences and Arts6 October CityEgypt; Analytical Chemistry DepartmentFaculty of PharmacyCairo UniversityCairoEgypt2020-01-092020-01-09201814690667https://doi.org/10.1177/1469066718788800PubMed ID 30012017https://t.ly/3GXPdScopusAn efficient, selective, sensitive, and rapid ultra-performance liquid chromatography tandem mass spectrometry method was established and validated for the quantification of pramipexole dihydrochloride monohydrate and levodopa simultaneously in human plasma with the aid of diphenhydramine as an internal standard. A simple protein precipitation technique with HPLC grade acetonitrile was efficiently utilized for the cleanup of plasma. The analysis was performed using a Hypersil gold 50 mm � 2.1 mm (1.9 �m) column and a mobile phase of 0.2% formic acid and methanol (90: 10 v/v). The triple-quadrupole mass spectrometer equipped with an electrospray source operated in the positive mode was set up in the selective reaction monitoring mode (SRM) to detect the ion transitions m/z 212.15 ?153.01, m/z 198.10? 135.16, and m/z 255.75 ? 166.16 for pramipexole dihydrochloride monohydrate, levodopa, and diphenhydramine, respectively. The method was thoroughly validated according to FDA guidelines and proved to be linear, accurate, and precise over the range 100-4000 pg/mL for pramipexole dihydrochloride monohydrate and 60-4000 ng/mL for levodopa. The proposed method was effectively applied for monitoring both drugs in plasma samples of healthy volunteers. The Author(s) 2018.Englishdiphenhydraminehealthy volunteerslevodopaPramipexole dihydrochloridemonohydrateultra-performance liquid chromatography tandem mass spectrometryLiquid chromatographyMass spectrometryPlasma (human)DiphenhydramineHealthy volunteersLevodopaPramipexoleUltra performance liquid chromatographyDrug productsdopamine receptor stimulating agentlevodopapramipexolebloodchemistrydrug stabilityevaluation studyhigh performance liquid chromatographyhumanintravenous drug administrationprocedurestandem mass spectrometryAdministration, IntravenousChromatography, High Pressure LiquidDopamine AgonistsDrug StabilityHumansLevodopaPramipexoleTandem Mass SpectrometryArticlehttps://doi.org/10.1177/1469066718788800PubMed ID 30012017