Quantification of Amiridine in Human Plasma by High-Performance Liquid Chromatography Coupled with Electrospray Tandem Mass Spectrometry

The aim of this study was to develop and validate a high-performance liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for analysis of the amiridine in human plasma. The analyte and internal standard (IS), zolpidem, were extracted from human plasma by solid phase extraction (SPE with SOLA cartridges) and separated on a Zorbax SB-C18 column using methanol and 0.2% formic acid in water as mobile phase. Detection was performed using an electrospray ionization source and mass spectrometric positive multireaction monitoring mode (+MRM) at a voltage capillary of +2000？V. The assay was linear over the concentration range 0.5–200？ng/mL with the lowest limit of quantification (LLOQ) of 0.5？ng/mL. The method also afforded satisfactory results in terms of the sensitivity, specificity, precision (intra- and interday %), accuracy, recovery, and the stability of the analyte under various conditions. The method can be successfully applied to pharmacokinetic studies. 1. Introduction Alzheimer’s disease (AD) is a devastating disease that results in the deterioration of memory, cognitive function, and the ability to care for oneself. AD, the most prevalent form of dementia, accounts for 50 to 70 percent of dementia cases and significantly impacts patients, families, caregivers, communities, and society as a whole [1, 2]. One of the most popular therapeutic strategies in AD is the control of cholinergic neurotransmission by the slow decline of neuronal degeneration or increasing cholinergic transmission [3]. Cholinesterase inhibitors are the mainstay treatment, yet they provide only limited and transient improvement in AD [1]. Amiridine (ipidacrine, neuromidin), 9-amino-2,3,5,6,7,8-hexahydro-H-cyclopenta[b]quinoline is a nonselective inhibitor of acetylcholinesterase and butyrylcholinesterase [4, 5]. The chemical structure of amiridine as shown in Figure 1 [6]. This circumstance stipulated using amiridine for the treatment of patients with mixed vascular and Alzheimer’s dementia of mild and moderate severity [7]. Figure 1: Chemical structure of amiridine. Appropriate analytical method is an urgent need to study amiridine’s pharmacokinetic properties. The HPLC-UV approach for content determination has been applied to a preclinic investigation of amiridine [8]. Unfortunately, this method was not sensitive enough for human pharmacokinetic studies of amiridine. LC/MS spectrometry based techniques are now the mainstay for such pharmacokinetic studies because of sensitivity, selectivity, speed, and cost effectiveness [9]. HPLC-MS/MS method for quantification of