Simultaneous Estimation of Metoprolol and Telmisartan Dosage Form

 

Jane J.*, Mani Prasad

Associate Professor, Dept. of Pharma. Chemistry, NGSM Institute of Pharmaceutical Sciences,

Paneer, Deralakatte-575018, Mangalore

*Corresponding Author E-mail: janempharm@gmail.com

 

ABSTRACT:

Metoprolol and Telmisartan is a multicomponent dosage form belonging to the class of antihypertensives. The main aim of the study was to develop economical simple, rapid, accurate , precise, sensitive and reliable for their routine analysis.  Two methods were developed. A simultaneous estimation of metoprolol and telmisartan by UV spectrophotometry, secondly by RP-HPLC. Method 1 was estimated by three multicomponent analysis procedure, in method 1a the estimation of Metoprolol and Telmisartan was based on Simultaneous equation analysis for  metoprolol and telmisartan by UV absorption at 276nm and 296nm respectively and linearity was observed in the concentration range of  20-100 μg/mL for both  the drugs. Method 1b, simultaneous estimation by Q-analysis based on isoabsorptive point(269 nm) and at 296 nm.  Method 1c, was absorption correction method were the linearity was observed between 20-100μg/ml at their respective absorption maximas.  Method 2  involved an  isocratic elution  of  Metoprolol and Telmisartan in a column of phenomenex C18,250x4.6,5μ, using a mobile phase of composition acetonitrile and ammonium acetate buffer of pH 3.5 in the ratio 70:30 v/v at a flow rate of 1ml/min and the analyte was monitored at 269nm. The chromatograms of the standard and dosage forms of metoprolol and telmisartan were recorded and linearity was observed in the concentration range of 30-70 μg/ml and 24-56 μg/ml respectively. All the developed methods were extended to formulations.Various degradation studies like acid, base, oxidative and thermal degradation were carried out. All the methods were validated based on ICH guidelines and were found to be simple reliable and the results are reproducible.

 

KEYWORDS: metoprolol, telmisartan, simultaneous estimation, HPLC..


 

INTRODUCTION:

Chemically Metoprolol1 is 1-(isopropyl amino)-3 [–4(2 methoxy ethyl) phenoxy] propan-2-ol belonging to the category of selective β1 blocker used to decrease cardiac output and blood pressure.

 

Telmisartan is an angiotensin II receptor blocker, mainly used as an antihypertensive agent.. Chemically it is 2-(4-{[4-methyl 6-1-methyl-1H- 1,3 benzodiazol-2-yl) -2-propyl 1H-1,3 benzodiazol-1yl] methyl}phenyl) benzoic acid.

Metoprolol and Telmisartan is a multicomponent dosage form, available as film coated tablets (METOSARTAN). Each tablet contains 50mg of Metoprolol Succinate and 40mg of Telmisartan. Literature survey revealed reverse phase HPLC and spectrophotometric analysis as the official methods of estimation for Metoprolol Succinate and Telmisartan individually and in combination with other drugs3-8. Most of the reported methods were carried out on biological samples.

 

The present study aims at developing analytical methods that are simple, rapid, and accurate, precise, sensitive and reliable for their routine analysis. The methods were validated based on ICH guidelines2.

 

MATERIALS AND METHODS:

Analytical grade methanol was used for simultaneous estimations. HPLC grade (Merck) solvents Acetonitrile, water, acetic acid, o-phosphoric acid and ammonium acetate were used for estimation by HPLC. Both metoprolol and telmisartan were obtained as gift samples from Ajanta Pharma Ltd, Bangalore and Cadila Pharmaceuticals Ltd, Ankleswar respectively. A UV-Visible double beam spectrophotometer, model Shimadzu UV-1700 with1cm matched quartz cuvette was used for simultaneous estimations.  The chromatographic estimation was carried out on a Shimadzu liquid chromatograph, model LC-10ATVP with a UV visible detector, SPD-10AT VP using a phenomenex, Luna 5μ C-18(2) 100A, 250x4.6mm column.

 

Method 1a: By simultaneous equation analysis. Accurately weighed quantities(100 mg) of metoprolol and telmisartan each were taken into 100ml conical flasks  separately and dissolved in 10 ml of methanol and then made to the required volume using methanol. Further dilutions were carried out to get a working concentration of 100μg/ml and 10μg/ml of metoprolol and telmisartan respectively. The solutions were scanned between 200nm-400nm to determine the absorption maxima and their isobestic point. Metoprolol and telmisartan showed absorption maxima at 276 nm and 296 nm respectively and isobestic point was found to be 269nm as shown in fig 1.  

 

The linearity for both the drugs was measured at the λmax of Metoprolol and Telmisartan (at 276 and 296nm)   and was found to show linear response in the range of 20-100 µg/ml.The developed procedure was extended to formulation of Metoprolol and Telmisartan, the combination was available in the market under the brand name Metosartan of strength 50 mg and 40 mg of Metoprolol and Telmisartan respectively. Average weight of twenty tab were taken and crushed to make  powder, weighed powder containing 100 mg Metoprolol was transferred to 100ml of volumetric flask and volume was made up to the mark with Methanol ( Metoprolol 1000 μg/ml  and Telmisartan 800 μg/ml). From the stock solution further dilutions were done to get the concentration of 50 µg/ml and 40 µg/ml Metoprolol and Telmisartan respectively. The same procedure as mentioned for the pure drug was followed for the formulation. The concentrations of both Metoprolol and Telmisartan were determined by measuring absorbance at 276 nm and 296 nm.

 

Method 1b: By Q Analysis:

Aliquots of   Metoprolol and Telmisartan were suitably diluted with methanol to get a concentration of 100 µg/ml and 10 µg/ml respectively. The linearity for both the drugs was measured at the λmax of Telmisartan and at the isobestic point  ( 296 and 269nm)   and was found to obey Beer’s in the range of  20-100 µg/ml.

 

The same procedure was extended to formulations as per the procedure mentioned in method 1a but the absorbance values were measured at the absorption maxima of telmisartan and at the isobestic point.

 

The concentration of Metoprolol and Telmisartan were calculated by applying following equations.           

Cx = ( Qm-Qy / Qx-Qy ) . A / ax     

Cy = ( Qm-Qx / Qy-Qx ) . A / ay

Cx, Cy ---- concentration of Metoprolol and Telmisartan respectively. (g/100 ml)

Qx ----ratio of absorptivity of Metoprolol at 296 and269 nm

Qy ----ratio of absorptivity of Telmisartan at 296 and 269 nm

Qm ----ratio of absorbance of  Mixture at 296 and 269 nm

A ----absorbance of  Mixture at Isobestic point  

ax----absorptivity of Metoprolol at Isobestic point  ay----absorptivity of telmisartan at isobestic point

Method 1c: Absorption correction method:

Cx  = C Ax 279 nm / A (1%, 1cm) 279 nm of metoprolol  

Cy = A 296 nm / A (1%, 1cm) 296 nm of telmisartan

CAx 279 nm = A 279 nm – Ay279 nm

Ay296 nm = Cy X  A (1%, 1cm) 279 nm of telmisartan

Where Cx and Cy are concentration (g/100ml) of metoprolol and telmisartan respectively. A 296 nm and A 279 nm absorbance of mixture at 296 and 279 nm respectively. CAx 279 nm is corrected absorbance of metoprolol and Ay296nm absorbance of telmisartan at 279nm.

 

Method 2:

The stock solution was prepared by accurately weighing 100mg of metoprolol and 80 mg of Telmisartan into a 100 ml volumetric flask and the diluent used for the make of volume is acetonitrile and acetate buffer of pH 3.5 in the ratio 70:30. From the stock solution 5ml of the stock solution is diluted to 100ml with ACN:Acetate buffer (70:30) , so as to get a conc. 50 µg/ml and  40 µg/ml of Metoprolol and  Telmisartan respectively. The linearity of the samples of Metoprolol and Telmisartan   was prepared by suitably diluting working solution and found to be in the range of 30-75 µg/ml  conc. for the Metoprolol and  24-60 µg/ml for  Telmisartan.

 

Chromatographic conditions

Mobile phase

Acetonitrile:aceate buffer(70:30)

Analytical column

Phenomenex ,C18,250X4.6mm,5μ

Temperature

Ambient

λ max

269nm

Flow rate

1ml/min

Injection volume

10 ml

Run time

10 min

Rt (metoprolol)

2.297 min

Rt (telmisartan)

4.370 min

Operation Pressure

100-110 Kgf

 

The same procedure was extended to formulation.

 

RESULTS AND DISCUSSION:

The developed methods are statistically validated to prove the methods are intended for analytical application. Simultaneous estimation of Metoprolol and Telmisartan was developed by UV spectrophotometry. Wavelengths selected were 276nm for Metoprolol and 296 nm for Telmisartan. The correlation coefficients of the drug solution were found to be 0.999 and 0.999.  Values were calculated for both the drugs at selected wavelengths and substituted in the equation for determining conc of the drugs in the formulation. Accuracy of the method was ascertained by recovery studies and results are expressed as % recovery. Values of standard deviation and coefficient of variation was satisfactorily low indicating the accuracy of the method. The developed methods were validated using ICH guidelines. Linearity of the proposed spectroscopic method was observed in concentration range 20-100 µg/ml. The precision of the developed method was evaluated based on intraday and interday measurements. Specificity of the method was assertained by comparing absorbance  of in the formulation was observed. Percentage recovery was found to be 99.38-100.94 and 100.94-102.38 for Metoprolol and Telmisartan respectively and validated for precision, accuracy and repeatability of the method. The low LOD and LOQ of both drug shows the sensitivity of the method. RP-HPLC method was optimized with a view to develop an accurate and stable assay method for estimation of Metoprolol and Telmisartan in a tablet formulation. A Phenomenex, C18 (250 x 4.6mm, 5µ.) column in isocratic mode was used, with a mobile phase ACN:Acetate buffer pH 3.5  [70:30] . The flow rate was 1 ml/min with detection at 269 nm. The linearity was assessed by plotting conc Vs area and is linear in the range of 30-70 µg/ml and 24-56 µg/ml for Metoprolol and Telmisartan respectively with correlation coefficient of 0.999 and 0.998. The %RSD for intraday and interday precision was less than 2% and the method was found to be reproducible. The LOD of the proposed method was 0.0550 and 0.0090  µg/ml and LOQ was 0.1813 and 0.0296 µg/ml for Metoprolol and Telmisartan respectively. The assay procedures were repeated five times and the results were found to give 98.44% of Metoprolol and 98.56 % of Telmisartan. Degradation studies are also performed for the proposed method and found to be no significant degradation of the formulation. All the results are given in the tables below.


 


 

 

Method 1a: Optical characters and precision data of metoprolol and telmisartan by simultaneous equation  method

Parameter

METOPROLOL

TELMISARTAN

276 nm

296 nm

276 nm

296 nm

Beer’s law limits (µg/ ml)

20-100

20-100

20-100

20-100

Absorptivity

47.857

0.505

267.292

470.907

Molar absorptivity (1 /mol/cm)

1.26 x10

0.1461 x 102

11.52 x10

19.49 x10

Correlation coefficient (r)

0.999

0.937

0.999

0.998

Sandell’s sensitivity

0.211

5.956

0.037

0.022

Regression equation

y = 0.0044x+ 0.0477

y = 0.0001x- 0.0012

y = 0.032x+ 0.000

y = 0.039x+ 0.0432

Standard deviation

0.011

0.000

0.001

0.001

Relative standard deviation

0.461

0.000

0.064

0.041

LOD (µg/ ml)

0.750

0.000

0.1021

0.0829

LOQ (µg/ ml)

2.2727

0.000

0.3096

0.2513

% Error at 99% (0.01 level)

0.570

0.000

0.079

0.051

% Error at 95% (0.05 level)

0.385

0.000

0.053

0.035

 

Method 1a: precision data

Drug

Labelled Amount (mg)

INTRADAY

INTERDAY

% Label claim

%RSD (n=5)

% Label claim

%RSD  (n=5)

METOPROLOL

50

101.30

1.8095

99.51

1.8767

TELMISARTAN

40

100.94

1.8190

102.02

1.2562

 

Drug

Labelled Amount (mg)

INTRADAY

INTERDAY

% Label claim

%RSD (n=5)

% Label claim

%RSD (n=5)

METOPROLOL

50

99.38

1.5297

99.01

1.6277

TELMISARTAN

40

101.73

1.8359

101.88

1.8361

 

Method 1b: Precision data


Method1b: Optical characters and precision data of metoprolol and telmisartan by Q-Analysis

Parameter

METOPROLOL

TELMISARTAN

269 nm

296 nm

269 nm

296 nm

Beer’s law limits (µg/ ml)

20-100

20-100

20-100

20-100

Absorptivity

35.723

0.505

435.542

470.907

Molar absorptivity (1 /mol/cm)

7.99 x102

0.1461 x 102

18.86 x103

19.49 x103

Correlation coefficient (r)

0.999

0.937

0.999

0.998

Sandell’s sensitivity

0.279

5.956

0.023

0.022

Regression equation

y = 0.0044x +0.0034

y = 0.0001x – 0.0012

y = 0.032x +0.0315

y = 0.039x+ 0.0432

Standard deviation

0.001

0.000

0.001

0.001

Relative standard deviation

0.684

0.000

0.059

0.041

LOD(µg/ ml)

0.750

0.000

0.1021

0.0829

LOQ(µg/ ml)

2.2727

0.000

0.3096

0.2513

% Error at 99%(0.01 level)

0.846

0.000

0.073

0.051

% Error at 95%(0.05 level)

0.572

0.000

0.049

0.035

 

Method 1c: optical characteristics of metoprolol and telmisartan by absorption correction method

PARAMETER

METOPROLOL

TELMISARTAN

276 nm

296 nm

276 nm

296 nm

Beer’s law limits (µg/ ml)

20-100

20-100

20-100

20-100

Absorptivity

47.857

0.505

267.292

470.907

Molar absorptivity (1 /mol/cm)

1.26 x103

0.1461 x 102

11.52 x103

19.49 x103

Correlation coefficient (r)

0.999

0.937

0.999

0.998

Sandell’s sensitivity

0.211

5.956

0.037

0.022

Regression equation

y = 0.0044x +0.0477

y = 0.0001x -0.0012

y = 0.032x +0.000

y =0.039x  +0.0432

Standard deviation

0.011

0.000

0.001

0.001

Relative standard deviation

 

0.461

0.000

0.064

0.041

LOD(µg/ ml)

0.750

0.000

0.1021

0.0829

LOQ(µg/ ml)

2.2727

0.000

0.3096

0.2513

% Error at 99%(0.01 level)

0.570

0.000

0.079

0.051

% Error at 95%(0.05 level)

0.385

0.000

0.053

0.035

 

Method 1c: Precision data

Drug

Labelled Amount (mg)

INTRADAY

INTERDAY

% Label claim

%RSD (n=5)

% Label claim

%RSD  (n=5)

METOPROLOL

50

100.69

1.8095

102.33

1.0181

TELMISARTAN

40

101.08

1.8183

101.60

1.7723

 

 


Parameter

METO

PROLOL

TELMI

SARTAN

λmax (nm) selected

269

269

Beer’s law limits (µg/ml)

30-70

24-56

Theoretical plates

1471.25

5443.25

Correlation coefficient (r)

0.999

0.998

Relative standard deviation (%)

1.4618

1.4735

% Error at 99%(0.01 level)

1.249

0.321

% Error at 95%(0.05 level)

0.844

0.217

Limit of detection (µg/ml)

0.0550

0.0090

Limit of Quantification (µg/ml)

0.1813

0.0296

Method 2: optical characteristics

 

Method 2: Precision data

Drug

Concentration (μg/ml)

System precision

Method precision

% recovery

%RSD

% recovery

%RSD

Metoprolol

50

98.44

1.46

99.42

1.76

Telmisartan

40

98.56

1.47

98.93

1.41

 

 

 

Different degradation studies like acid, base oxidative and thermal were also carried out. Results of which are shown below.

Degradation data

Drug

Degradation

Area

(mV.s)

% Recovered

% Degraded

Metoprolol

Acid

104.905

89.73

10.27

Base

106.667

99.69

0.31

Oxidative

97.328

88.12

11.88

Thermal

87.928

78.12

21.88

Telmisartan

Acid

589.116

92.81

7.19

Base

601.585

101.47

-

Oxidative

558.840

93.64

6.36

Thermal

520.780

85.21

14.79

 

REFERENCES:

1.       Indian Pharmacopoeia, Govt. of India, Ministry of Health and Welfare. Published by IP commission Ghaziabad; 2010; Vol I and II: 1682,2187-8.

2.       International Conference on Harmonization, Guidance for industry in Q2B.Validation on Analytical Procedures, Methodology. Switzerland. IFPMA. 1996: 1-8.

3.       Mayur Modi, Rikin Shah, RC Mashur, Development and validation of spectrometric methods for simultaneous estimation of metoprolol and telmisartan in combined pharmaceutical formulation ,IJPSR,2012,3,(5),1348-1354.

4.       Patel Prashant B, Marihia Bhavin P, Shah Shailesh A, Shah Dinesh, Second order derivative spectrophotometric method for the estimation of telmisartan and metoprolol in tablet dosage, IRJP, 2012,3,(5).

5.       Joshi Pryanka and Kumar Mukesh, Development and validation of a reverse phase HPLC method for the simultaneous estimation of Metoprolol and Telmisartan in tablet dosage form, Pelagia Research Library, Der Pharmacia Sinica, 2011, 2 (3): 211-219

6.       Manisha B. Jadhav, Sachin S. Suryawanshi, Sachin R. Tajane, Tarkase K.N. development and validation of UV spectrophotometric method for determination of metoprolol succinate and telmisartan in tablet dosage form,  Int J Pharm Pharm Sci, 2012, 4, (3 ), 387-389

7.       Prajakta S. Nawale, Atul A. Shirkhedkar, Sanjay J. Surana, and Amod S. Patil, Normal and Reversed-Phase HPTLC Methods for Simultaneous Estimation of Telmisartan and Metoprolol Succinate in Pharmaceutical Formulation, Analytical Chemistry. Volume 2012 (2012

8.       Alagar Raja, M.; Spoorthy, N.; Banji, David; Rao, K. N. V.; Vanitha, C.; Selva Kumar, D., Simultaneous estimation of metoprolol succinate and telmisartan in tablet dosage form by RP-HPLC, Journal of Pharmacy Research;2012, Vol. 5 Issue 8, p4585

 

 

 

 

Received on 04.07.2014                Modified on 18.07.2014

Accepted on 30.07.2014                © RJPT All right reserved

Research J. Pharm. and Tech. 7(9): Sept. 2014  Page 1020-1024