A Simple Rp- HPLC Method for Simultaneous Estimation of Six Cardiovascular Drugs in Bulk and Dosage Form

IOSR Journal of Pharmacy and Biological Sciences (IOSR-JPBS)
e-ISSN: 2278-3008, p-ISSN:2319-7676. Volume 10, Issue 1 Ver. II (Jan -Feb. 2015), PP 32-37
www.iosrjournals.org
DOI: 10.9790/3008-10123237 www.iosrjournals.org 32 | Page
A Simple Rp- HPLC Method for Simultaneous Estimation of Six
Cardiovascular Drugs in Bulk and Dosage Form
Celina Nazareth1
*, B. Shivakumar2
, P. Reddy3
, S. Acharya4
and S. Verekar4
1
*PES’s Rajaram and Tarabai Bandekar College of Pharmacy, Farmagudi, Goa, India,
2
BLDEA College of Pharmacy, Bijapur, India,
3
Samskruti College of Pharmacy, Kondapur, Hyderabad, India,
4
VerGo Pharma Research Laboratories Pvt. Ltd., Verna, Goa, India.
Abstract: A simple, convenient Rp-HPLC method has been developed and validated for the simultaneous
estimation of Metolazone, Indapamide, Nebivolol, Rosuvastatin, Olmesartan and Spironolactone. The column
used was an Inertsil ODS 3 V column of 250 mm length × 4.6 mm ID, with 3 micron particle size of adsorbent.
Separation was achieved using isocratic elution in a buffer-acetonitrile-methanol mobile phase at a flow rate of
1.2 ml/min. The detection was performed at wavelength of 225 nm using a UV detector. The column temperature
was 450
C and injection volume was 20µl. The method was validated for precision, linearity and accuracy. The
% RSD for all the drugs was found to be less than 2 %. The correlation coefficient (r2
) was not less than 0.999
for all drugs. The mean percent recovery of the drugs from tablet placebo at 50%, 100% and 150% were within
limits. The marketed formulations of the drugs were analyzed and the mean assay results were found to be
within limits. The developed method can thus be employed for routine simultaneous analysis of Metolazone,
Indapamide, Nebivolol, Rosuvastatin, Olmesartan and Spironolactone in bulk and in their marketed
formulations.
Keywords: Rp-HPLC method, Indapamide, Metolazone, Spironolactone, Olmesartan, Nebivolol, Rosuvastatin.
I. Introduction
As per World Health Organization, Cardiovascular Diseases (CVDs) are the number one cause of death
globally. Although many CVDs can be treated or prevented, an estimated 17.1 million people die of CVDs each
year1
. CVDs are caused by disorders of the heart and blood vessels, and include coronary artery disease (heart
attacks), cerebrovascular disease (stroke), raised blood pressure (hypertension), peripheral artery disease,
rheumatic heart disease and congenital heart disease. The major causes of CVDs are tobacco use, stress,
inadequate or lack of sleep, physical inactivity, an unhealthy diet and harmful use of alcohol.
Congestive Cardiac Failure (CCF) is one of the complications of Coronary Artery Disease. It is a
chronic and usually progressive illness which occurs when, cardiac output is insufficient to meet the demands of
tissue perfusion, resulting in a clinical syndrome of decreased exercise tolerance with pulmonary and systemic
venous congestion2
. Combination of drugs are needed to control the risk factors associated with CCF and these
include diuretics, angiotensin II receptor antagonists, β1 receptor blockers and statins.
Metolazone [3-7] is an oral diuretic agent commonly classified with the thiazide diuretics. It is useful to
treat Congestive Heart Failure and Hypertension. Indapamide [3-7] is a non-thiazide, sulphonamide diuretic
drug which reduces blood pressure at doses causing little diuresis. It is generally used in the treatment of
hypertension, as well as decompensated cardiac failure. Nebivolol hydrochloride [5-8] is a β1 -blocker (anti-
hypertensive) which reduces peripheral vascular resistance and significantly increases stroke volume, with
preservation of cardiac output. Olmesartan medoxomil [5-7, 9], a recent member of angiotensin receptor blocker
(ARB) class of drugs, is indicated in the treatment of hypertension and prevention of diabetic nephropathy and
congestive cardiac failure. Rosuvastatin [5, 7, 10] reduces levels of low-density lipoprotein, apolipoprotein B
and triglycerides in the blood, while increasing levels of high-density lipoprotein in the management of
hyperlipidaemia. Spironolactone [3-7, 11] is a potassium sparing diuretic agent.
Literature survey revealed that different analytical methods like UV spectroscopy, Rp-HPLC, High
Performance Thin Layer Chromatography (HPTLC) [12-33] have been reported for the analysis of the above
drugs individually and in combination with other drugs. However, there has been no study involving
simultaneous estimation by HPLC of above six drugs. Hence, in the present study a simple Rp-HPLC method,
for the simultaneous analysis of above mentioned cardiovascular drugs in bulk and tablet dosage form has been
developed and validated.

A Simple Rp- HPLC Method For Simultaneous Estimation Of Six Cardiovascular Drugs…
Fig. 1 Chemical structure of drugs
II. Materials And Methods
2.1 Chemicals and reagents
All chemicals and reagents used were of analytical grade. Olmesartan medoxomil was obtained as a
gift sample from Unichem laboratories Ltd., Pilerne, Goa; Rosuvastatin from VerGo Pharma Research
Laboratories Pvt. Ltd., Verna, Goa; Nebivolol HCl from Glenmark Generics, Goa; Metolazone and
Spironolactone from Centaur pharmaceuticals Pvt. Ltd., Tivim, Goa and Indapamide from Adcock Ingram Ltd.,
Bangalore. Tablet formulations were procured from the local market.
2.2 HPLC Instrument and Chromatographic conditions
The instrument used for analysis was of Agilent Technologies “1120 Compact LC” with UV detector
and Inertsil ODS 3 V column of 250 mm length × 4.6 mm ID, with 3 micron particle size of stationary phase.
The mobile phase used was buffer-methanol-acetonitrile in the proportion of 45:33:22, v/v/v. The column
temperature was 450
C, the flow rate was 1.2 ml/min and injection volume was 20µL.
2.3 Preparation of standard and sample solutions
A mixed standard solution of the drugs was prepared by accurately weighing the quantity of drugs as in
Table 1, into a 100 ml volumetric flask. About 75ml of diluent (ACN & MilliQ water, 1:1, v/v) was added and
the solution was sonicated for 10 minutes. The volume was made to 100ml with diluent and mixed. The solution
was centrifuged at 4000 rpm for 10 mins. A volume of 4 ml diluted to100ml using diluent was injected 5 times
and peak areas were determined.
Table 1 Weight of drugs in standard solution
Drug Metolazone Indapamide Nebivolol HCl Olmesartan
medoxomil
Rosuvastatin Spironolactone
Weight in mg 10 30 60 30 30 30
Ten tablets of each drug sample were accurately weighed and average weight determined. Tablet
powder equivalent to 5 mg of drug was weighed and transferred to 50ml volumetric flask. About 35ml of diluent
was added and the mixture was sonicated for 10 minutes. The volume was adjusted with diluent and mixed.
Aliquot solution was then centrifuged at 4000 rpm for 10 mins. The centrifugate was appropriately diluted and
the solution was injected and peak area was determined. The percentage purity of the tablets was calculated.
2.4 Method validation
The developed method was validated for linear range, accuracy, precision and specificity [33].
2.4.1 Linear range
The linearity of the method for each drug was studied by preparing 5 different concentrations of the
drugs as in Table 2. The solutions were injected in the HPLC system and peak areas were recorded. Calibration
curves were constructed by plotting peak areas versus concentration of each drug and the linear range was
determined. The linear regression equation and correlation coefficient for each drug was determined.

Table 2 Concentration of drugs in working standard solutions
Vol (ml) of
std stock in
100ml
Metolazone
in ppm
Indapamide
in ppm
Nebivolol
HCl in ppm
Olmesartan medoxomil
in ppm
Rosuvastatin
in ppm
Spironolactone
in ppm
2 2 6 12 6 6 6
3 3 9 18 9 9 9
4 4 12 24 12 12 12
5 5 15 30 15 15 15
6 6 18 36 18 18 18
2.4.2. Precision
Precision of the method for each drug was determined by performing repeatability studies by the
successive analysis of six injections of above solution, corresponding to 100% of drug concentration. The
percentage RSD was determined.
2.4.3. Accuracy
Accuracy of the developed HPLC method was determined by carrying out recovery studies for each
drug at spike level 50% (L1), spike level 100% (L2) and spike level 150% (L3) concentration by replicate
analysis (n=3). A volume of 2ml, 4ml and 6ml of standard drug solution (corresponding to 50%, 100% and
150% concentration of each drug) was added to 50 mg of placebo powder taken in 3 different 50ml volumetric
flask. Around 35ml of diluent was added and solution was sonicated for 10 mins. The volume was made up with
diluent and mixed. Aliquot of the solution was centrifuged at 4000 rpm for 10 mins. The clear centrifugate was
diluted appropriately and injected. The percentage of total drug content recovered was calculated.
2.4.4.. Specificity
The specificity of the method was determined by injecting the diluent and placebo solution in the
chromatographic system and observing the chromatograms.
2.5 System suitability testing
System suitability of the system was determined by six replicate injections. The acceptance criteria
adopted was less than 2 % RSD for peak areas, greater than 2000 (USP) theoretical plates and asymmetry factor
between 0.85 and 2.0.
III. Results And Discussion
3.1 Method development
The solubility of the drugs was tested in acetonitrile (ACN), methanol, ACN & MilliQ water mixture
(1:1, v/v), methanol & MilliQ water mixture (1:1, v/v), 0.1N HCl and phosphate buffer pH 6.8. Based upon the
free solubility of the drugs, ACN & MilliQ water (1:1, v/v) mixture was selected as diluent for method
development and validation. The drug concentrations were optimized so as to obtain absorbance values in the
range of 0.3 to 0.9. UV Spectra of the drugs as studied from Fig. 2 revealed that a wavelength of 225 nm could
be used as a common wavelength for analysis.
Chromatographic separation of the drugs was tried on YMC Pack Pro C18 RS column having a length
of 250mm with 4.6 mm ID and particle size of stationary phase being 5 micron. The mobile phase used was
buffer-methanol-acetonitrile in the proportion of 45:33:22, v/v/v. The column temperature was maintained at
250
C and flow rate of mobile phase chosen was 1 ml/min. However, results were not satisfactory as Nebivolol
and Rosuvastatin were not resolved and Retention time (Rt) of Spironolactone was more than 20 mins. Several
parameters were verified including, alteration of column temperature (300
C, 400
C, 450
C) and flow rate of mobile
phase (1.2 ml/min), with no improvement in the resolution. Hence, change of column, so as to increase the
surface area of adsorbent and increased carbon loading, was tried. An Inertsil ODS 3 V column of 250 mm
length × 4.6 mm ID, with 3 micron particle size was used. Optimum separation of the drugs was finally
achieved on the column as seen in Fig. 3, with column temperature of 450
C and 1.2 ml/min flow rate of mobile
phase. The injection volume was 20µL. There were no interferences from the diluent and placebo, as seen in
Fig. 4.
The calibration curve of the drugs as in Fig. 5 gave linear lines. The results of accuracy and precision
studies as depicted in Table 3 proved that the results were satisfactory. The proposed Rp-HPLC method was
applied to marketed formulations of the drugs. The results, as tabulated in Table 4, were within acceptable
limits.
The results of system suitability testing as depicted in Table 5 proved that the parameters were within
the acceptable limits.

Fig. 2 UV Spectra for standard drugs
Fig. 3 Chromatogram showing separation of drugs
(a) (b)
Fig. 4 Chromatogram for (a) diluent and (b) placebo

Fig. 5 Calibration curves for drugs
Table 3 Results of Accuracy and Precision analysis
Met Ind Neb Ros Olm Spi
% Recovery L1 (n=3) 100.95 100.97 100.75 100.71 99.83 100.47
% Recovery L2 (n=3) 100.45 100.11 100.57 100.39 99.70 100.46
% Recovery L3 (n=3) 99.73 99.19 99.98 99.79 99.24 99.93
Precision % RSD (n=6) 0.07750 0.06111 0.18673 0.13247 0.20606 0.16094
Table 4 Results for assay of marketed formulations
Formulation Metoz 2.5 Natrilix Nebi 5 Roseday Olmetrack 20 Aldactone
Mfg. By Centaur Pharma Serdia Otsira Genetica USV USV RPG Life Sciences
Drug Metolazone Indapamide Nebivolol Rosuvastatin Olmesartan Spironolactone
% Purity 98.38 104.33 97.51 104.72 102.15 98.38
Table 5 Results for system suitability testing
Drug Metolazone Indapamide Nebivolol Rosuvastatin Olmesartan Spironolactone
Peak Area (%RSD) 0.3 0.269 0.5 0.293 0.170 0.225
Theoretical plates 8580 9291 5947 9466 10780 10690
Asymmetry factor 1.112 1.076 1.064 1.040 1.046 0.955
IV. Conclusion
A simple, isocratic LC method has been developed, optimized and validated for the simultaneous
estimation of Metolazone, Indapamide, Nebivolol, Rosuvastatin, Olmesartan and Spironolactone. The method is
simple, rapid, accurate, precise and specific. It can be used for the routine analysis of the six cardiovascular
drugs without the need for separation, in bulk and in their dosage form.
Acknowledgements
Authors are thankful to VerGo Pharma Research Laboratories Pvt. Ltd., Verna, Goa, India, for
providing the facilities to conduct this research work and also to Unichem laboratories Ltd., Pilerne, Goa,
Glenmark Generics, Goa, Centaur pharmaceuticals Pvt. Ltd., Tivim, Goa, and Adcock Ingram Ltd., Bangalore
for gift samples of the drugs.

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A Simple Rp- HPLC Method for Simultaneous Estimation of Six Cardiovascular Drugs in Bulk and Dosage Form

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