Simultaneous Determination of Telmisartan and Amlodipine in Tablets by Reverse Phase High Performance Liquid Chromatography

 

M.P. Yeole* and A. J. Asnani

J. L. Chaturvedi College of Pharmacy, Electronic zone, MIDC, Hingana, Nagpur-16

*Corresponding Author E-mail: mp­_yeole@rediffmail.com

 

ABSTRACT:

A simple, sensitive and accurate RP-HPLC method has been developed and subsequently validated for simultaneous determination of telmisartan and amlodipine besylate. The separation was carried out by using mobile phase consisting of acetonitrile, methanol and phosphate buffer pH4.5 in the ratio (15:35:50) v/v and adjusted pH±0.1 with phosphoric acid. The column used was SS Wakosil-II C-18 with flow rate of 1ml/min and UV detection at 255nm. The described method was linear over a concentration range of 10.0-400µg/ml and 1-80µg/ml for the assay of telmisartan and amlodipine besylate respectively .The mean percentage recoveries obtained for telmisartan was 98.2% and for amlodipine besylate 99.5% when determined at five different levels. The proposed method is precise, accurate, selective and rapid for the simultaneous determination of telmisartan and amlodipine besylate-

 

KEYWORDS: Hypertension, RP-HPLC, Simultaneous, Analysis

 

 

INTRODUCTION:

Telmisartan and amlodipine besylate as components of multi-ingredient formulations is useful in management of hypertension.

 

Structure of Telmisartan

 

Telmisartan, 4-(2-n-propyl-4-methyl-6-(1-methyl benzimidazol-2-yl)- benzimidazol-1-yl)methyl) -biphenyl-2-carboxylic acid is an angiotensin II receptor antagonist(ARA II) widely used in the treatment of hypertension. The therapy with these drugs offers a good quality of life for hypertensive patients due to the absence of side effects and its once daily administration1.The key advantages of the non-peptide ARA II antagonists are related to their specificity of action and minimization of untoward effects2.

 

Structure of Amlodipine besylate

 

Amlodipine besylate is calcium antagonist and chemically it is 3-methyl 5-methyl-(4RS)-2-[(2-aminoethoxy) methyl]-4-(2-chlorophenyl)-6- methyl-1,4 dihydropyridine-3,5-dicarboxylate benzene sulphonate used in the treatment of hypertension and angina pectoris3.

 

Literature survey reveals the availability of several method for the estimation of telmisartan (TELM) and Amlodipine besylate (AMLO) individually by HPLC4,5 and spectrophotometric6. No method has been reported for the estimation of TELM and AMLO in combined dosage form.  The aim of present work is the quantitative estimation of TELM and AMLO in their combined dosage form by HPLC.

 

Table:1- Determination of telmisartan and amlodipine besylate content in Tetan-am tablets

Sr. No.

Content of Telmisartan (mg/tablet)

Amount of Telmisartan found     (mg/tablet)

Content of Amlodipine besylate (mg/tablet)

Amount of Amlodipine besylate found (mg/tablet)

1

40

39.5

5

4.95

2

40

39.2

5

4.96

3

40

39.3

5

4.93

 

Table: 2- Results of marketed formulation, recovery and intermediate precision

Drugs

Parameters

%Labeled claim

%Recovery

Intermediate Precision*

Interday

Intraday

Different Analyst

Telmisartan

Mean

98.33

98.84

98.25

99.02

98.85

±SD

0.425

0.728

0.717

0.525

0.568

%RSD

0.412

0.712

0.710

0.518

0.518

Amlodipine

Besylate

Mean

98.93

99.25

99.34

98.25

99.10

±SD

0.275

0.815

0.234

0.618

0.483

%RSD

0.260

0.805

0.225

0.601

0.462

*Mean

 

Material And Method:

Telmisartan and amlodipine besylate of pharmaceutical grade were kindly supplied as gift samples by Alembic Limited. Acetonitrile HPLC grade, methanol HPLC grade, potassium hydrogen phosohate, orthophosphoric acid and water (double distilled) were used. The LC system consisted of Shimadzu LC-10AT pump, SS Wakosil II C-18, 250×4.6mm, 5µm column, Rheodyne injector equipped with a 100µl sample loop and UV Shimadzu SPD-10A VP detector set at 255nm.

 

Preparation of Standard Solution: The standard solution containing telmisartan 20 mg/100ml and amlodipine besylate 2.5mg/100ml was prepared by dissolving in mobile phase.

 

Preparation of Sample Solution: Weighed accurately tablet powder equivalent to 20mg and telmisartan and 2.5 mg of amlodipine besylate was weighed and transferred to 100 ml volumetric flask. About 70 ml of mobile phase was added and shaken mechanically for 15 minutes. The mixture was then sonicated in ultrasonic bath for5 minutes and makes the volume upto 100ml by mobile phase. The solution was filtered with Whatman filter paper no.1.

 

Procedure:

Mobile phase was prepared by acetonitrile, methanol and phosphate buffer pH4.5 in the ratio (15:35:50) v/v and adjusted pH = 4.5±0.1 with phosphoric acid with flow rate 1ml/min at 255nm. The working standard solution was injected into the chromatograph. The retention time for telmisartan and amlodipine besylate at flow rate of 1ml/min were recorded 6.3 min and 3.5min respectively .Analysis of marketed sample Tetan-Am (Alembic Ltd, India) of three different batches was carried out and recorded peak area of standard and marketed sample .The result of the analysis are tabulated in Table 1.

 

Validation of method:7

The method was validated in terms of linearity, accuracy, precision and specificity of the sample application .The linearity of the method was investigated by serially diluting the stock solution of telmisartan and amlodipine besylate and measure peak area versus concentration. The linearity range was found to be10-400µg/ml and 1-80µg/ml for telmisartan and amlodipine besylate. Recovery studies were carried out to study the accuracy of the proposed method and ascertained by standard addition method (Table-2). A known amount of drug was added to preanalysed tablet powder at three levels and the percentage recoveries were calculated. Precision was found to be lower than 2%. Ruggedness of the proposed method is determined by analysis of aliquots from homogenous slot by different analysts using similar operational and environmental condition. Specificity study was performed by keeping the sample under various conditions at 60°C and 50°C by adding 1ml of 0.1N HCl, 0.1 N NaOH, 3%H2O2exposing with UV light at 255nm.

 

Result and Discussions:

Tablets were analyzed and amount of drug determined by proposed method was in good agreement with the labeled claim. The results of the marketed formulations were found to be 98.33±0.425 and 98.93±0.275 for telmisartan and amlodipine besylate respectively. The proposed method was validated as per the ICH guidelines. Linearity was determined at different concentration, telmisartan and amlodipine besylate shows linearity in the concentration range of 10-400µg/ml and 1-80µg/ml respectively .The system reproducibility was determined by five replicate and five times measurement of a laboratory mixture at the analytical concentration. The reproducibility of sample was expressed in terms of S.D and %R.S.D. There was no interference from the common excipients present in the tablets .The recovery of drug was determined at 80, 100 and 120% levels. The % recovery was 98.84% for telmisartan and 99.25%for amlodipine besylate indicating that method has required accuracy .Specificity studies results reveal that both the drugs degraded in presence of peroxide. Ruggedness was performed under three different conditions different days, different analysts and intraday .The results show the %RSD values <2.0% signifies the precision of the method. The proposed method for simultaneous estimation of AMLO and TEL in combined dosage form was found to be simple, accurate and rapid and can be employed for estimation of pharmaceutical formulations in quality control departments.

 

Conclusion:

The proposed method is specific, accurate, rugged, robust and precise as found from the laboratory studies. The method when applied for the determination of telmisartan and amlodipine besylate in combined dosage marketed formulations gave results conforming to the labeled claim of the drug.

 

References:

1)       M.T. Velasquez, Arch. Fam. Med. 5(1996) 351-356

2)       R.T. Eberhardt, R.M. Kevak,P.M. Kang, W.H. Frishman, J. Clin. Pharmacol. 33(1993) 1023-1038

3)       J.E. Arrowsmith, S.F. Campbell, P.E. Cross, J.K. Stubbs, R.A. Burges, D. G. Gardinar, K.L. Blackburn, Long-acting dihydropyridine calcium antagonists, 1,2-Alkoxymethyl derivatives incorporating basic substituent, J. Med. Chem. 29(1986)1696-1702

4)       Determination of telmisartan by HPLC Sun-l; Shen-J.F, Tao dr, Zhu-DQ, second, Med Uni, Shanghai

5)       Determination of amlodipine in tablets by HPLC by Shang F, Shang KH; Pfizer Pharma Ltd Dalian 116600, China

6)       A Spectrophotometric method for the determination of amlodipine besylate in pure form and in tablets AU Prabhakar, AH Giridhar-R, Maharaja Sayajirao Univ. Baroda. Fac. Technol and Engn, Baroda 390001

7)       PARTII: Validation of analytical procedure: methodology Q2B, ICH Harmonized Tripartite Guidelines, 1996; 6-12.

 

 

 

 

 

Received on 09.04.2010       Modified on 05.05.2010

Accepted on 31.05.2010      © RJPT All right reserved

Research J. Pharm. and Tech. 4 (1): January 2011; Page 75-77