title: A validated, sensitive HPLC-MS/MS method for quantification of cis-para-methyl-4-methylaminorex (cis-4,4'-DMAR) in rat and human plasma: application to pharmacokinetic studies in rats.
abstract: 4,4'-DMAR is an analogue of the known psychostimulants 4-methylaminorex and aminorex. In the light of reports of deaths associated with its abuse, and the easy access from Internet vendors, the EU Council recently decided on control measures across member states. Here we describe a validated method for measuring plasma levels of cis-4,4'-DMAR, crucial for preclinical studies and analysis in human plasma. Chromatographic separation was done by gradient elution on a Kinetex C18 column with 0.1% formic acid in water and 0.1% formic acid in acetonitrile at 0.2 mL/min. Detection was by positive electrospray ionization (ESI+) in multiple reaction monitoring mode monitoring the quantifier transitions m/z 191.4 → m/z 148.3 for cis-4,4'-DMAR and m/z 259.3 → m/z 194.2 for carbamazepine (internal standard). Protein precipitation with 1% of formic acid in acetonitrile was used in cis-4,4'-DMAR extraction from plasma; recovery was high (>93%) with a negligible matrix effect. This method provides an accurate, precise, and sensitive method for cis-4,4'-DMAR quantification in human and rat plasma, following European Medicine Agency guidelines for bioanalytical method validation. Pharmacokinetic studies were conducted in rats. After an intravenous dose of 1 mg/kg, plasma levels declined rapidly (≥80% in 4 h), followed by a slow elimination phase (t1/2of 5.14 ± 0.65 h). Absorption was rapid after intraperitoneal injection (tmax= 15 min) with a rapid decline thereafter; Cmaxand AUC0-240minshowed dose-proportionality over the dose range 1-10 mg/kg. This method was successfully applied to investigate pharmacokinetic properties in rats and could be used to quantify cis-4,4'-DMAR levels in human plasma. Copyright © 2016 John Wiley & Sons, Ltd.
authors: Department of Biochemistry and Molecular Pharmacology, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors: Jacopo
authors: J
authors: Lucchetti
authors: Department of Neuroscience, IRCCS -Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors: Claudio M
authors: CM
authors: Marzo
authors: Department of Neuroscience, IRCCS -Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors: Angelo
authors: A
authors: Di Clemente
authors: Department of Neuroscience, IRCCS -Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors: Luigi
authors: L
authors: Cervo
authors: Department of Biochemistry and Molecular Pharmacology, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors: Marco
authors: M
authors: Gobbi
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D013287:Illicit Drugs / Q000097:blood*; D057230:Limit of Detection; D008297:Male; D010080:Oxazoles / Q000097:blood*; D011619:Psychotropic Drugs / Q000097:blood*; D051381:Rats; D017208:Rats, Wistar; D015813:Substance Abuse Detection / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D013287:Illicit Drugs; D010080:Oxazoles; D011619:Psychotropic Drugs; C000598109:para-methyl-4-methylaminorex
keywords: HPLC-MS/MS; new psychoactive substances; para-methyl-4-methylaminorex; pharmacokinetics; plasma