Development and Validation of a Simultaneous HPLC Method for Assay and Dissolution of Bisoprolol fumarate and Amlodipine besylate in Pharmaceutical Dosage.

 

Dr. Shalini Pant* and Krishan Pal

1Principal, S.S.D.P.C. Girls Post Graduate College, Roorkee-247667, Uttarakhand, India
2K.L.D.A.V. (P.G.) College, Roorkee Haridwar, Uttrakhand India -247667


ABSTRACT:

A fast and robust RP-HPLC method was developed for simultaneous determination of bisoprolol fumarate and amlodipine besylate in pharmaceutical dosage form. A mixture of buffer prepared by 0.4ml of TEA and 3.12 gm of Sodium dihydrogen orthophosphate in 1000 ml water adjusted to pH 3.0ą0.05 and acetonitrile (50:50) was used as mobile phase at 1.0 ml/min flow rate.  A widely used stationary phase i.e. C18 column (5μ, 250×4.6 mm ID) in pharmaceutical industry was selected and UV detection was performed at 230 nm. retention time was obtained as 4.4 minutes and 6.4 minutes for bisoprolol and amlodipine respectively. Linearity was established in the range 1.3μg/ml to 10.8μg/ml. Correlation coefficients were 0.9999 and 0.9988 for bisoprolol and amlodipine respectively. Mean recoveries were obtained as 99.25% and 99.96% for bisoprolol fumarate and amlodipine besylate respectively.

 

KEYWORDS: Bisoprolol fumarateamlodipine besylate, RP-HPLC

 

INTRODUCTION:

Bisoprolol fumarate is a synthetic beta1 -selective cardioselective adrenoceptor blocking agent. The chemical name for bisoprolol fumarate is (ą)-1-[4-[[2-(1-methylethoxy) ethoxy] methyl]phenoxyl-3-[(1-methylethyl)amino]-2-propanol(E)-2-butenedioate (2:1). It is a white crystalline powder, which is readily soluble in water, methanol, ethanol, and chloroform1. It is official in USP2.

 

Amlodipine besylate, a long-acting calcium channel blocker, is chemically described as 3-ethyl-5-methyl(ą)-2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridine dicarboxylate, mono benzenesulphonate. Amlodipine besylate is a white crystalline powder. It is slightly soluble in water and sparingly soluble in ethanol3. It is official in BP4. Beta blocker plus calcium channel blocker combinations have utility in certain cardiovascular diseases like angina pectoris, myocardial infarction and hypertension. A tablet formulation containing bisoprolol fumarate and amlodipine besylate has been recently introduced on the market.

 

Various methods for determination of bisoprolol by fluorimetry5,6, HPLC7–9 and densitometry10–12 are reported in literature.

 

Also HPTLC13–16, HPLC17–23, spectrophotometry 24–30 methods are reported for determination of amlodipine alone or in combination with other drugs. Combination of amlodipine and Bisoprolol Spectrophotometry32.

 

 


But literature survey did not reveal method for simultaneous determination of bisoprolol and amlodipine at normally available conditions. The aim of this study was to develop a fast, precise, accurate, rugged and robust RP-HPLC method for simultaneous determination of bisoprolol and amlodipine in tablets for assay and dissolution. Criteria employed for assessing the suitability of proposed method was cost effectiveness as well as fast analysis of routinely used analysis parameter.

 

MATERIAL AND METHOD:

A liquid chromatographic system comprising of Waters 2695 separation module and Waters 2996 PDA detector (Waters Corporation, Milford, USA) connected to Empower chromatography software for processing the data generated were used and LC-2010CHT (Shimadzu) connected with LC solution software. Reference standards of bisoprolol fumarate and amlodipine besylate were used. HPLC grade acetonitrile was purchased from Qualigens (Part of thermo Fisher Scientfic USA). Chemicals are used same ExcelaR grade was used and membrane filter paper Milipore. The combination tablets containing bisoprolol fumarate and amlodipine besylate (Concor AM, Merck, Zabesta-AM TABLETS- ACCENT Pharma) were procured from the market.

 

A buffer solution was prepared by adjusting the pH 3.0ą0.05 of 0.4 ml TEA and 3.12 gm of Sodium dihydrogen orthophosphate with 10% orthophosphate solution. The mobile phase was filtered and degassed mixture of buffer pH 3.0 and acetonitrile (50:50, v/v). Luna C18 column (5 μ, 250×4.6 mm), as well as Hibar(R)   RP-18e (5 μ, 250×4.6 mm), was used as stationary phase. A constant flow of 1.0 ml/min was maintained throughout the analysis. Detection was carried out using PDA/UV detector at 230 nm.

 

The description of the in vitro dissolution profiles was calculated by using model-independent method33-34 in this study, as model-independent approaches, two fit factors were applied to the dissolution data that compare the dissolution profiles of a pair of drug product. These fit factors directly compare the difference between the percent drug dissolved per unit time for a test and reference product. The fit factors are f1 (difference factor) and f2 (similarity factor).

 

Experimental work

Preparation of standard solution: A combined standard stock solution of bisoprolol fumarate and amlodipine besylate was prepared dissolving in 5 ml of Acetonitrile and finaly make up with mobile phase to obtain the solution having 250 μg/ml concentrations. 2ml of standard stock solution was diluted to 100 ml with mobile phase to obtain a 5.0 μg/ml solution of bisoprolol and amlodipine and used as working standard for assay analysis. 2ml of standard stock solution was diluted to 100 ml with mobile phase. Further 5 ml dilute to 10ml with dissolution medium and used as working standard for dissolution analysis.

 

Preparation of sample Solution: Twenty tablets were weighed and crushed to fine powder. An accurately weighed portion of the powder equivalent to 10 mg of bisoprolol fumarate and 10 mg of amlodipine was taken in 100 ml volumetric flask, about 10 ml of acetonitrile was added to it and flask was kept in an ultrasonic bath for 2 min with intermittent swirling. These solutions were then diluted to the mark with mobile phase and filter through whatman no 1 filter paper. 5ml of the filter solution was diluted to 100 ml with mobile phase and mixed. This solution was filtered through Millipore membrane filter and used for assay analysis. Dissolution analysis carried out in 900 ml of 0.01N Hydrochloric Acid at 75 RPM, 20minutes for Bisoprolol and 30 minutes for Amlodipine. Dissolution sample further diluted 5ml to 10 ml with mobile phase.

 

Procedure: 20μl of working standard and sample solution were injected into the chromatograph and the peak areas were recorded for assay analysis. While 50μl of working standard and sample solution were injected into the chromatograph and the peak areas were recorded for Dissolution analysis. The amount of each active was computed by external standard quantification method.

 

RESULT AND DISCUSSION:

In order to optimize the LC separation of bisoprolol and amlodipine, initially, mobile phases of buffer and acetonitrile were used. The retention behavior of both the drugs was studied with respect to pH of buffer solution in the range of 2.5 to 5.0, and aqueous composition of mobile phase. Retention of both the drugs was found slightly dependant on pH of buffer (slight increase in retention with increase in pH). Bisoprolol was found relatively less sensitive to aqueous composition as against amlodipine, which was found more sensitive to aqueous composition. A 5% percent increase in aqueous composition resulted in 1.05 and 1.31 times increase in retention for bisoprolol and amlodipine respectively. The buffer solution of pH 3.0 and mobile phase composition of buffer: acetonitrile (50:50) was found most appropriate for separation of bisoprolol and amlodipine on Luna C18-2 column and Hibar (R) RP18e. Flow rate was optimized based on column efficiency. Bisoprolol and amlodipine were well resolved in reasonable time of about 10 minutes run time. The retention times were 4.43minutes and 6.42minutes respectively. The resolution between bisoprolol and amlodipine was 7.46 the dilution of analytes with mobile phase helped to minimize the interference due to blank peaks. The wavelength of 230 nm was selected for the UV detection because at this wavelength there was maximum overlap of the spectra of bisoprolol and amlodipine.

 

To ascertain effectiveness of system suitability test, six replicate injections of freshly prepared working standard solution were injected into the chromatograph and relative standard deviation (RSD) of peak areas was calculated. System suitability parameters such as tailing factor, resolution and theoretical plates of a typical chromatogram are tabulated in Table1.

 

Table No -1 System Suitability (n=6)

Parameter

Bisoprolol Fumarate

Amlodipine Besylate

Retention Time (min)

4.4380ą0.0040

6.4245ą0.0065

Theoretical Plates (N)

6373.3265ą53.1866

6856.0577ą42.7427

Tailing Factor

1.3693ą0.0123

1.6167ą0.0360

Resolution

0.00

7.4582ą0.0257

Area Of Peak

125413.50

237418.17

RSD of peak Area

0.5800

1.2551

 

Linearity (described by equation and corresponding correlation coefficient) was determined using eleven calibration levels for both the compounds (at 25-200% levels). The concentrations of calibration solutions of both the drugs were from 1.30 to 10 μg/ ml. The method of linear regression was used for data evaluation. Peak area of standard compounds was plotted against respective concentrations. The limit of Detection (LOD) and limit of Quantification (LOQ) of the developed method were determined by injecting blank (n=6) and standard solutions (n=6) using the developed RP-HPLC method during system suitability Test and calculated on based of signal to noise ration of blank finally verified at nearest concentration. The LOD is the smallest concentration of the analyte that gives a measurable response (signal to noise ratio of 3). Method Precision were observed intraday as well as inter days (table-2).      

The LOD for Bisoprolol Fumarate and Amlodipine Besylate were found to be 0.022 and 0.022 μg /ml respectively. The LOQ is the smallest concentration of the analyte, which gives response that can be accurately quantified (signal to noise ratio of 10). The LOQ was 0.066 and 0.066μg/ml Bisoprolol Fumarate and Amlodipine Besylate respectively. To confirm the accuracy of the proposed method, recovery experiments were carried out by standard addition technique. Three different levels of standards were added to pre-analyzed tablet samples in triplicate. The mean percentage recoveries of bisoprolol and amlodipine were 99.25% and 99.96% respectively.

 

Table No -2 Validation Parameters:

Ingredient

Bisoprolol Fumarate

Amlodipine Besylate

Linearity Range

1.3878 to 11.1022

1.361 To 10.885

Correlation Coefficients

0.9999

0.9988

0.9998

0.9976

Limit of Detection (mcg)

0.022

0.022

Limit of quantitation (mcg)

0.067

0.066

Recovery (n=3)

99.25% SDą0.9350

99.96% SDą0.6688

Precision (RSD) 

Intraday (N=6)

0.283%

0.780%

Inter day (n=12)

0.482%

0.722%

 

The proposed method was subjected to robustness studies with respect to change in pH of buffer (ą0.5 units), change in mobile phase composition (ą10%), change in column temperature (ą5°C) and change in flow rate (ą0.1 ml).The method was found robust with respect to variability in above conditions (table -3).

 


 

Table No -3 (A) Bisoprolol Fumarate (n=6)

Parameter

Retention Time

Tailing factor

Theoretical Plate

Area

RSD (n=6)

Initial conditions

4.4380 SD ą0.0040

1.3693 SD ą0.0123

6373 SD ą53

125413

0.5800

Flow 0.9 ml

4.9336 SD ą0.0040

1.4028 SD ą0.0073

6117 SD ą83

143482

0.8691

Flow 1.1 ml

4.0230 SD ą0.0178

1.2372 SD ą0.0115

6475 SD ą24

118297

0.2998

Temperature 20°C

4.4485 SD ą0.0071

1.3830 SD ą0.0109

6307 SD ą70

125820

0.4915

Temperature 30°C

4.4488 SD ą0.0110

1.3163 SD ą0.0148

6503 SD ą72

124525

0.2788

Solvent -10%

4.6423 SD ą0.0116

1.3273 SD ą0.0047

6064 SD ą41

133635

0.8968

Solvent +10%

4.2098 SD ą0.0129

1.2919 SD ą0.0036

6638 SD ą114

113583

1.0771

 

 

Table No -3 (B)  Amlodipine Besylate (n=6)

Ingredient

Retention Time

RRT

Resolution

Tailing factor

Theoretical Plate

Area

RSD (n=6)

Initial conditions

6.4245 SD ą0.0065

1.4476 SDą0.0003

7.4582 SDą0.0257

1.6167 SDą0.0360

6856 SD ą42

237418

1.2551

Flow 0.9 ml

7.1351 SD ą0.0045

1.4462 SDą0.0009

8.0525 SDą0.0394

1.6328 SDą0.0143

6393 SD ą25

264270

0.2471

Flow 1.1 ml

5.8256 SD ą0.0037

1.4481 SDą0.0061

7.0267 SDą0.0147

1.5524 SDą0.0034

6909 SD ą72

206761

1.2309

Temperature 20°C

6.4382 SD ą0.0196

1.4473 SDą0.0034

7.3887 SDą0.0143

1.6247 SDą0.0184

6741 SD ą60

258765

0.9777

Temperature 30°C

6.3942 SD ą0.0554

1.4373 SDą0.0035

7.5368 SDą0.0194

1.5583 SDą0.0081

6927 SD ą41

249555

0.1736

Solvent -10%

8.3173 SD ą0.0110

1.7916 SDą0.0057

8.0830 SDą0.0451

1.5392 SDą0.0190

6433 SD ą76

295660

0.3986

Solvent +10%

5.1215 SD ą0.0050

1.2166 SDą0.0043

6.1828 SDą0.0382

1.4837 SDą0.0179

7224 SD ą39

193409

0.3083

 

Table No -3 (C) effect of pH

pH

Retention Time

RRT of Amlodipine

Resolution Amlodipine

Tailing Factor

Theoritical Plate

Bisoprolol

Amlodipine

Bisoprolol

Amlodipine

Bisoprolol

Amlodipine

2.50

4.326

6.200

1.433

7.412

1.333

1.542

6632

6952

3.00

4.433

6.416

1.447

7.483

1.364

1.567

6445

6889

3.50

4.727

6.755

1.429

7.685

1.392

1.483

6385

6982

 

Table No -4 Comparison

Parameter

Bisoprolol Fumarate

Amlodipine Besylate

Concor-AM

Zabesta-AM

Concor-AM

Zabesta-AM

Assay

4.96mg

4.98mg

5.04mg

4. 991mg

(99.25%)

(99.55%)

(100.77%)

(99.82%)

SDą0.2809

SDą0.4824

SDą0.7856

SDą0.6413

Dissolution

87.25%

85.23%

89.36%

86.25%

Similarity Factor

51.31

52.41

Difference factor

10.79

13.01

 

 

 


The content of actives found in the commercial brand of tablets (Concor AM, Merck, Zabesta-AM TABLETS- ACCENT Pharma) by proposed method. The low values of RSD indicates that method is precise for assay and dissolution (Table -4). Intermediate precision was studied using different column, HPLC instrument and performing the analysis on different day.

 

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Received on 19.12.2011

Accepted on 24.01.2012     

Š A&V Publication all right reserved

Research Journal of Pharmaceutical Dosage Forms and Technology. 4(1): Jan. - Feb., 2012, 62-66