Journal of Applied Pharmaceutical Science Vol. 10(04), pp 075-099, April, 2020 Available online at http://www.japsonline.com DOI: 10.7324/JAPS.2020.104012 ISSN 2231-3354 Forced degradation study of efonidipine HCl ethanolate, characterization of degradation products by LC-Q-TOF-MS and NMR Charu P. Pandya, Sadhana J. Rajput * Department of Pharmaceutical Quality Assurance, Faculty of Pharmacy, The Maharaja Sayajirao University of Baroda, Center of Relevance and Excellence in New Drug Delivery System, Government of India, Vadodara, Gujarat, India. ARTICLE INFO Received on: 23/09/2019 Accepted on: 24/12/2019 Available online: 04/04/2020 Key words: Forced degradation, efonidipine, preparative HPLC, LC-Q-TOF-MS, NMR and IR. ABSTRACT Efonidipine HCl Ethanolate is an antihypertensive drug with 1,4 dihydropyridine and phosphinane derivative. Forced degradation study was performed in Efonidipine as per the guidelines by International Conference on Harmonization (ICH) Q1A (R2). Extensive degradation and slight degradation were observed in alkaline and photolytic conditions, respectively, whereas acidic, oxidative, and thermal conditions did not show any degradation. Degradation products were separated on Thermo Hypersil BDS C18 column (250 × 4.6 mm, 5 µ), mobile phase in gradient mode using ammonium acetate buffer and acetonitrile with detection at a wavelength of 254 nm. Six degradation products in alkaline condition and four degradation products in photolytic condition were identifed by HPLC and characterized by mass spectrometry using LC-Q-TOF-MS, and degradation pathway was proposed. This is the typical case of degradation, where co-solvent methanol reacts with Efonidipine to form pseudo degradation products such as DP1, DP4, DP5, and DP6. Three degradation products DP1, DP3, and DP4 in alkaline condition were isolated by preparative HPLC and were characterized by LC-Q-TOF-MS, 1 H/ 13 C NMR, and IR techniques. By characterization with these techniques, DP1 is characterized as 3-2-(N-benzylanilino)ethyl 3-oxo-2,2-dimethylpropyl hydrogen 1,4-dihydro-2,6-dimethyl-4- (3-nitrophenyl) pyridin-3-yl-3-phosphonate, DP3 is characterized as 2-(N-benzyl-N-phenylamino) ethanol, and DP4 is characterized as 3-methoxy-2,2-dimethylpropyl hydrogen 1,4-dihydro-2,6-dimethyl-5-methyloxycarbonyl-4-(3- nitro)phenylpyridin-3-yl-3-phosphonate. The developed method was validated as per guidelines by ICH with respect to linearity, accuracy, precision, limit of detection, and robustness. INTRODUCTION Efonidipine HCL Ethanolate (EFO) is a new calcium channel blocker with dihydropyridine and phosphinane derivative. It blocks both T-type and L-type calcium channels (Hikaru and Koki, 2002; Masuda and Tanaka, 1994; Nakano et al., 2010). It has a slow onset and longer duration of action. In a patient with essential hypertension, it causes an increase in renal blood fow, a decrease in renal vascular resistance, and an increase in glomerular fltration rate. It chemically consists of 2-(N-benzylanilino) ethyl 5-(5, 5-dimethyl-2-oxo-1, 3, 2˄5}-dioxaphosphinan-2-yl)-2, 6-dimethyl-4-(3-nitrophenyl)-1, 4-dihydropyridine-3-carboxylate, ethanol, hydrochloride with molecular formula C 36 H 45 ClN 3 O 8 P, and molecular weight 714.19 g/mole (Pubchem, 2019). Efonidipine has pKa (basic) of 2.33 and log P is 5.35 (Drugbank, 2019). It was approved in 1995 as a brand name Landel ® . It is approved for marketing in India by Drug controller general India to Zuventus Pharma as Efnocar ® . The HPLC method development of EFO has been reported (Kumar et al., 2017). The LC-MS/MS method has been reported for the development of EFO in human plasma for pharmacokinetic applications and its stereospecifc determination (Liu et al., 2015; 2016). Literature has been reported on spectroscopic studies on the interaction of efonidipine with bovine serum albumin (Wang et al., 2008), and the development considerations * Corresponding Author Sadhana J. Rajput, Department of Pharmaceutical Quality Assurance, Faculty of Pharmacy, The Maharaja Sayajirao University of Baroda, Center of Relevance and Excellence in New Drug Delivery System, Government of India, Vadodara, Gujarat, India. E-mail: sjrajput @ gmail.com © 2020 Pandya and Rajput. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).