Journal of Applied Pharmaceutical Science Vol. 5 (07), pp. 122-129, July, 2015 Available online at http://www.japsonline.com DOI: 10.7324/JAPS.2015.50719 ISSN 2231-3354 Application of Bromocresol Green and Bromothymol Blue for the Extractive Spectrophotometric Determination of Anti-hypertensive Drugs Akram M. El-Didamony1, Sameh M. Hafeez2, Ahmed A. Saad1 1 Chemistry Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt. 2 Ismailia Chemical Laboratory, Forensic Medicine Authority, Justice Ministry, Egypt. ABSTRACT ARTICLE INFO Article history: Simple, selective and highly sensitive spectrophotometric methods are proposed for the rapid and accurate Received on: 10/04/2015 determination of anti-hypertensive drugs namely telmisartan (TEL), propranolol (PRO), bisoprolol (BIS) and Revised on: 02/05/2015 carvedilol (CRV) in tablets and biological fluids using bromocressol green (BCG) and bromothymol blue (BTB). Accepted on: 16/06/2015 The developed methods involve formation of stable yellow colored dichloromethane extractable ion-pair Available online: 27/07/2015 complexes of the amino derivative of four antihypertensive drugs such as TEL, PRO, BIS and CRV with two sulphonphthalein acid dyes, namely; BCG and BTB in acidic buffer. The effect of optimum conditions via pH on Key words: the ion-pair formation, reagent concentration, time and temperature and solvent was studied. The composition of Antihypertensive drugs, the ion-pairs was found 1: 1 by Job’s method. The established methods having high sensitivity and good Extraction spectrophotometry, selectivity could be applied to the determination of the studied drugs in pharmaceutical, urine and blood serum BCG and BTB dyes; Ion-pair samples with satisfactory results. The results obtained are good agreement with experimental data. The reaction complex, Pharmaceutical mechanism was also discussed. formulations. INTRODUCTION arrhythmia and so on (Sweetman, 2002). Its structure is shown in Fig.1. Several methods for the analytical determination of PRO in Telmisartan (TEL, Fig. 1a) is a highly selective pharmaceutical formulations have been reported in the literature, angiotensin II type 1 receptor antagonist, widely used in the by spectrophotometry (El-Didamony, 2010; Basavaiah et al., 2004; treatment of hypertension and heart failure (Yusuf et al., 2008; Zahálka et al., 2013), spectrofluorometry (Rekhi et al., 1995) and Pitt and Konstam, 1998). It can selectively block the angiotensin HPLC (Šatínský et al., 2013; Salman et al., 2010; El-Sahart, 2003; type 1 receptor without affecting other receptor systems involved Abdel-Hamid, 2000). Carvedilol (CRV, Fig. 1c) is a non-selective in cardiovascular regulation. Literature survey reveals several and β-adrenergic antagonist with no intrinsic sympatomimetic methods for determination of TEL individually in biological activity and is widely used to treat essential hypertension and fluids and formulation like LC (Babu et al., 2012; Gupta et al., angina pectoris (Anderson, 2002; Moffat et al., 2004). 2011; Rao et al., 2011; Jyothi and Nalluri, 2012), HPLC (Seelam Carvedilol is also indicated for the treatment of mild to et al., 2010; Zhang et al., 2009), voltammetry (Alarfaj, 2013), severe chronic heart failure, Left ventricular dysfunction following spectrophotometry and derivative spectrophotometry (Ilango and myocardial infarction in clinically stable patients and hypertension. Kumar, 2012; Qin et al., 2009). Propranolol (PRO, Fig. 1b) is β-blockers affect the heart and blood circulation (Flanagan, 1998). one of common β-blockers, which is widely used in clinical Analytical methods such as HPLC (Belal et al., 2013; Machida et treatment of cardiovascular diseases such as angina, hypertension al., 2003; Zarghi et al., 2007), differential pulse voltammetry (Dogan and Ozkan, 2005) and spectrofuorimetry (Önal, 2011; * Corresponding Author Cardoso et al., 2007) have been used for the determination of Akram M. El-Didamony, Chemistry Department, Faculty of Science, CRV. Zagazig University, Zagazig, Egypt. Email: [email protected] © 2015 Akram M. El-Didamony et al. This is an open access article distributed under the terms of the Creative Commons Attribution License -NonCommercial- ShareAlikeUnported License (http://creativecommons.org/licenses/by-nc-sa/3.0/). El-Didamony et al.. / Journal of Applied Pharmaceutical Science 5 (07); 2015: 122-129 123 Bisoprolol (BIS, Fig. 1d) is a second-generation selective solutions of pure TEL, PRO, CAR and BIS were beta-blocker without intrinsic sympathetic activity. It is effective prepared separately by dissolving accurately weighed 20 in reducing blood pressure (Dubach et al., 2002). Several mg of each drug in a 100 ml calibrated flask. Working analytical methods have been studied for the determination of BIS solutions of lower concentrations were freshly prepared in biological fluids. by appropriate dilution with water. ii. A 1.0×10-3 M of bromothymolol blue and bromcresol green (Aldrich Co., Ltd., Gillingham-Dorst, Germany), were prepared by dissolving accurate weight from each dye in 2 ml methanol then, add 20 ml distilled water and diluted to 100 ml in a calibrated flask with distilled water a- Telmisartan b- Propranolol to the mark. iii. Commercial dosage forms of TEL (Micardis 40mg, Boehringer Ingelheim Co., Germany), PRO (Inderal 10 mg, EIPICo 10th of Ramadan, Egypt), CRV (Carvid 7.5mg Multi-apex, Badr-city, Cairo) and BIS (10 mg/tablet Concor, product of Amoun Pharmaceutical c-Carvedilol d-Bisoprolol Co., El-Obour city, Egypt) . Fig. 1: Chemical structure of the studied drugs. iv. Series of buffer solutions of KCl-HCl (pH 1.0-2.2), NaOAc-HCl (1.99-4.92) and NaOAc-AcOH (3.4-5.6) pH Among these methods, HPLC (Joshi et al., 2010; Tutunji were prepared by standard methods. et al., 2009; Shaikh et al., 2008; Patel et al., 2006), LC–MS-MS (Peste et al., 2010; Ding et al., 2007; Caudron et al., 2004) have General Recommended Procedures been utilized for the determination of BIS. Some methods have Ion-pair Method Using BCG also been reported for the determination of BIS in pharmaceutical Into a series of separated funnels, accurately measured preparations. These articles include voltammetry (Goyal et al., aliquots of TEL, PRO, CRV and BIS in the concentration range 2008) and spectrophotometry (Sahu and Patel, 2006; El-Didamony shown in (Table 1) were pitted out. A volume of 2.0 ml of 1.0×10- et al., 2012; El-Didamony and Shehatab, 2014). 3M BCG was added. Then, 2.0 ml of the buffer solution of pH = 2 Hypertension is a major cause of morbidity and mortality for TEL or CRV and pH = 4 for PRO or BIS were added in each worldwide. Anti–hypertensive medication is effective in reducing case and the volume was completed to 10 ml with distilled water. blood pressure. Therefore, this paper proposes two simple and The contents were extracted with 10 ml dichloromethane and the sensitive extractive spectrophotometric methods for the organic layer was dried over anhydrous sodium sulfate. The determination of four antihypertensive drugs. The methods are absorbance of the yellow colored complexes was measured at 402 based on ion-pair complexes of drugs with dyestuffs such as against a reagent blank prepared similarly. Calibration plots were bromocresol green (BCG) and bromothymol blue (BTB) and drawn to calculate the amount of drugs in unknown analyte subsequent extraction into dichloromethane under reaction samples. conditions used. Ion-pair Method Using BTB MATERIALS AND METHODS Suitable aliquots of the stock solution of TEL, PRO, CRV and BIS in the concentration range shown in (Table 1) were Apparatus transferred into a series of 25 ml separated funnels. Then, 2.0 ml All the absorbance spectral measurements were made of the buffer solution of pH = 2 for TEL or CRV and pH 4 for using Shimadzu spectrophotometer model: 1800-240V, made in PRO or BIS were added in each case and the volume was Japan, spectral bandwidth 2.0 nm, with 10 mm matched quartz completed to 10 ml with distilled water. The contents were cells. The pH values of buffer solutions were measured using extracted with 10 ml dichloromethane and the organic layer was Jenway instrument pH-meter (combined electrode). dried over anhydrous sodium sulfate. The absorbance of each solution was measured at 402 nm against a reagent blank after 5 Reagents and Solutions min. A linear equation for each standard curve was calculated by All of the chemicals used were of analytical or linear regression. pharmaceutical grade and used without further purification. Double distilled de-ionized water was used to prepare all solutions. Procedure for Tablets i. Pharmaceutical grade of TEL, PRO, CRV and BIS Ten tablets of each commercial pharmaceutical certified to be 99.85% pure was obtained as gift were formulation for TEL, PRO, CRV and BIS were crushed, kindly supplied from Egyptian International Pharma- powdered, weighed out and the average weight of one tablet was ceutical Industries Company (EIPICo), Egypt. Stock determined. An accurate weight equivalent to 10 mg each drug and 124 El-Didamony et al.. / Journal of Applied Pharmaceutical Science 5 (07); 2015: 122-129 then active component was transferred into a 100 ml measuring hypsochromic shift was 28 nm. So 402 nm were chose as the flask. About 25 ml of distilled water was added and the mixture determination wavelength against dichloromethane. was shaken thoroughly for about 5 min. Then, it was diluted up to the mark with distilled water, mixed well and filtered using filter Optimization of the Reaction Conditions paper. An aliquot of this solution was diluted appropriately to A number of preliminary experiments established obtain the working concentrations and analyzed as described under optimum conditions necessary for rapid and quantitative formation the standard procedure. of colored ion-paired complexes to achieve the maximum stability and sensitivity. Optimum condition was fixed by varying one Procedures for Human Serum and Urine parameter at a time while keeping other parameter constant and The proposed methods were applied to the determination observing its effect on the absorbance. of the studied drugs in spiked urine and serum provided from several healthy volunteers.