Potentiometric Determination of Asenapine Maleate Using PVC Membrane and Carbon Paste Ion-selective Electrodes

Abstract

Asenapine maleate is a white to off-white non hygroscopic powder, slightly soluble in water (5.80 mg/mL) [1], sparingly soluble in 0.1 M HCl, soluble in methanol. The pH of a saturated asenapine solution in water is 4.2 at 23.5 0C, its pKa is 8.6. AS is atypical antipsychotic drug developed for the treatment of schizophrenia and acute mania associated with bipolar disorder [2]. It shows high affinity for numerous receptors like serotonin, adrenergic, dopamine, histamine [3]. Many methods have been mentioned in the literature for the determination of AS in pure form, in pharmaceutical formulation, as well as in biological fluids as, Titrimetric method [4], Spectrophotometric methods [5-8]. Gas chromatography [9], Liquid chromatography [10,11] and Thin layer chromatography [12]. Different HPLC methods using different mobile phases and detectors [13-24]. There were 5 stability indicating HPLC methods [25-29]. No electrochemical method was introduced for determination of asenapine. Ionselective electrodes have been used recently for quantitative determination of drugs as it has many advantages comparing to other sophisticated methods [30,31]. ISEs have low detection limit, good accuracy, wide concentration range and good applicability to turbid and coloured solutions. ISEs give high selectivity towards the drugs in the presence of different excipients. The proposed work introduces three different electrodes for the determination of asenapine maleate according to ICH guidelines [32]. The electrochemical sensitivity of the electrode is based on the incorporation of ion pair (AS-AR and AS–PTA) using PVC membrane and carbon paste (Figure 1). Figure 1: Chemical Structure of Asenapine Maleate.