HPTLC-Densitometric Analysis of Eperisone Hydrochloride and Paracetamol in Their Combined Tablet Dosage Form

A simple, precise, accurate, and reliable HPTLC method has been developed and validated for the analysis of EPE-Eperisone hydrochloride and PCM-Paracetamol in their combined dosage form. Identification and analysis were performed on 100？mm × 100？mm layer thickness 0.2？mm, precoated silica gel G60-F254 aluminum sheet, prewashed with methanol, and dried in an oven at 50°C for 5 min. Toluene : methanol : ethyl acetate : glacial acetic acid (4？:？3.5？:？2.5？:？0.05) (v/v/v/v) was used as mobile phase. Calibration plots were established showing the dependence of response (peak area) on the amount chromatographed. The validated calibration ranges were 200–700？ng/spot and 1300–4550？ng/spot for EPE and PCM with correlation coefficient (R2) 0.994 and 0.996, respectively. Average % recovery was between 98.61–100.94% and 99.18–100.57% for EPE and PCM, respectively. The spots were scanned at 248？nm in a reflectance mode. The proposed method was validated as per ICH guidelines and successfully applied to the estimation of EPE and PCM in their combined tablet dosage form. 1. Introduction EPE is chemically (2RS)-1-(4-ethylphenyl)-2-methyl-3-(1-piperidinyl)propan-1-one and hydrochloride (1？:？1) (Figure 1(a)) [1, 2]. Eperisone HCl is a centrally acting muscle relaxant; it acts at the level of spinal cord by blocking sodium channels and calcium channels. Eperisone HCl exerts its spinal reflex inhibitory action predominantly via a presynaptic inhibition of the transmitter release from the primary afferent endings via a combined action on voltage-gated sodium and calcium channels. Eperisone HCl increases the blood supply to skeletal muscles; this action is noteworthy since a muscle contracture may compress the small blood vessels and induce an ischemia leading to release of pain stimulating compounds [3]. EPE is official in Japanese pharmacopoeia [1]. Chemically PCM is N-(4-hydroxyphenyl)acetamide (Figure 1(b)). Paracetamol is a weak inhibitor of PG-Prostaglandin synthesis of COX-1 and COX-2. Cyclooxygenase serves as a pain activator, is responsible for the biosynthesis of prostaglandins, is used for the relief of headaches, fever, pains, and is a major ingredient in numerous cold and flu remedies [4]. Paracetamol is official in Japanese Pharmacopoeia [1], British Pharmacopoeia [5], United States Pharmacopoeia [6], and Indian Pharmacopoeia [7]. Figure 1: Chemical structure of (a) EPE and (b) PCM. The review of the literature revealed that analytical methods involving spectrophotometry [8], LC-ESI-MS [9], have been reported for EPE in single form and in combination with other