Electrochemical determination of antihypertensive drug irbesartan in pharmaceuticals Vinod K. Gupta a,b,⇑ , Rajeev Jain c , Shilpi Agarwal c , Ritesh Mishra c , Ashish Dwivedi c a Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667, India b Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia c School of Studies in Chemistry, Jiwaji University, Gwalior 474011, India article info Article history: Received 21 September 2010 Received in revised form 9 November 2010 Accepted 12 November 2010 Available online 19 November 2010 Keywords: Irbesartan Voltammetry Method development Surfactants Quantitative analysis abstract A sensitive voltammetric method has been developed for the determination of irbesartan in a Britton– Robinson buffer medium. Irbesartan exhibited a well-defined cathodic peak over the entire pH range from 2.0 to 12.0. The mechanism of reduction was postulated on the basis of controlled potential electrol- ysis, coulometry, and spectral analysis. Under optimal conditions, a linear response of irbesartan was obtained in the range from 3.0  10 5 to 5.7  10 3 mol L 1 and with a limit of detection of 5.33  10 7 mol L 1 . The effect of cationic surfactant on the voltammetric reduction peak of irbesartan in Britton–Robinson buffer is also described. Ó 2010 Elsevier Inc. All rights reserved. Irbesartan is a potent, long-acting, nonpeptide angiotensin II receptor antagonist [1] having high selectivity for the AT1 subtype (angiotensin I). It is potentially safe and more tolerable than other classes of antihypertensive drugs. Irbesartan reduces the chances of cardiac failure, myocardial infarction, sudden death, and death from progressive systolic failure. Chemically, irbesartan is 2-bu- tyl-3-{[2 0 -(1H-tetrazole-5-yl)(1,1 0 -biphenyl)-4-yl]methyl}-1,3-dia- za spiro[4,4]non-1-en-4-one (Scheme 1) [2]. Irbesartan is officially listed in Martindale: The Extra Pharmaco- poeia [3]. Its assay procedure in pure and dosage form is not re- ported in any pharmacopoeia; therefore, the development of an analytical procedure for the determination of irbesartan in phar- maceutical preparations is of great significance. A survey of the lit- erature revealed that few methods have been reported for its determination such as high-performance thin layer chromatogra- phy (HPTLC) 1 [4], high-performance liquid chromatography (HPLC) [5], capillary zone electrophoresis (CZE) [6,7], and derivative spectro- photometry [8]. During the past decades, modern electrochemical techniques [9–46] have been widely used for the determination of pharmaceu- ticals and other analytes. Furthermore, determination of irbesartan using an electrochemical method is yet to be reported. The objec- tive of current work was to develop a voltammetric method for the determination of irbesartan and to investigate its reductive proper- ties in the presence of surfactant. Additions of surface-active agents have proven to be an effec- tive role in the electroanalysis of biologically active compounds and drugs. Aqueous micellar solutions and micro emulsions are surfactant-based self-organized systems [47] that can be used as less hazardous and versatile substitutes for organic solvents in vol- tammetry [48], HPLC separation [49], and catalysis [50]. The influ- ence of surfactant aggregates at the electrode–electrolyte interface in micelle solutions has been indicated. The use of surfactants as drug carriers makes necessary the study of the interaction of drugs with micellar systems, implying the elucidation of the nature of these interactions. Solubilization of electroactive compounds in aqueous solutions containing surfactant micelles provides a new medium for electrochemical studies. Materials and methods Irbesartan (99% pure) was a gift from Sunpharma Pharmaceuti- cals (Mumbai, India). A tablet form containing irbesartan (Irovel, 300 mg) was obtained from commercial sources. A stock solution of irbesartan (2.8  10 3 mol L 1 ) was prepared by direct dissolution in N,N 0 -dimethylformamide (DMF) and in 0003-2697/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.ab.2010.11.024 ⇑ Corresponding author at: Department of Chemistry, Indian Institute of Tech- nology Roorkee, Roorkee 247 667, India. E-mail addresses: vinodfcy@iitr.ernet.in, vinodfcy@gmail.com (V.K. Gupta). 1 Abbreviations used: HPTLC, high-performance thin layer chromatography; HPLC, high-performance liquid chromatography; CZE, capillary zone electrophoresis; DMF, N,N 0 -dimethylformamide; CTAB, cetyltrimethylammonium bromide; DPP, differential pulse polarography; DME, dropping mercury electrode; SCE, saturated calomel electrode; CV, cyclic voltammetry; PAR, Princeton Applied Research; LOD, limit of detection; LOQ, limit of quantitation. Analytical Biochemistry 410 (2011) 266–271 Contents lists available at ScienceDirect Analytical Biochemistry journal homepage: www.elsevier.com/locate/yabio