INTRODUCTION:

Felodipine is a long-acting calcium channel blocker (dihydropyridines class) used as an anti-hypertensive and in the treatment of angina.^1,2 Chemically it is ethylmethyl-1,4-dihydro-2,6-dimethyl-4-(2,3 dichlorophenyl)-3,5-pyridindicarboxylate (Fig.1).³

Extensive literature review reveals that several spectrophotometric and HPLC⁴, Colorimetric analysis⁵ methods have been reported so far for determination of felodipine alone and its combination with other drugs. Therefore, it was thought worthwhile to develop simple, accurate and reliable spectrophotometric method for estimation of felodipine in bulk and in tablet dosage form using methanol as a solvent. All the chemicals used were of analytical grade. Spectral and absorbance measurement were made on Systronics Double beam UV-Visible spectrophotometer 2203 with 10 mm matched quartz cells.

Objective:

The main aim of the current study is to develop simple, accurate and reliable spectrophotometric method for determination of felodipine in tablet dosage forms.

MATERIALS AND METHODS:

Preparation of standard solution: An accurately weighed 10 mg of felodipine pure drug was dissolved in Methanol to give stock solutions of drug 100 µg/mL concentration. From this stock solution, working standard solution of drug (10-100 µg/mL) were prepared by appropriate dilutions with same solvent. Working standard solutions were scanned in UV range of (200-400nm) and overlain UV spectra of felodipine as shown in fig. 2. Calibration curve for felodipine was plotted as shown in fig. 3.

Fig. 1: Structure of Felodipine

The optical characteristics such as Beer’s law limits, regression equation and correlation coefficient were calculated and results are presented in Table 1.

Preparation of sample solution:

Twenty tablets were weighed accurately and ground to fine powder. An accurately weighed powder equivalent to 10 mg of felodipine was transferred to 100 mL volumetric flask and volume make up to the mark with methanol. From this stock solution, working sample solution of drug was prepared by appropriate dilutions with same solvent. The results of assay are presented in Table 2.

Fig. 2: Overlain Spectra of Felodipine

Fig.3: Calibration curve of Felodipine

Table 1: Optical Characteristics and Precision of the proposed method

Parameters	Results
Wavelength	362.4 nm
Beer’s law limit (µg/mL)	10-100
Regression equation (Y= mx+C)	Y= 0.019x+0.058
E 1%	766.8
Slope (m)	0.019
Intercept (C)	0.058
Correlation Coefficient (r)	0.991

Table 2: Results for Assay of Felodipine

^aLabel claim

mg/tab

*Amount found mg/cap

% label claim

(% ± S.D.)

% RSD

5.0

4.96

99.20 ± 0.2069

0.0128

Average of three determinations* ^aTablet: Felogard 5 (Cipla ltd. Daman.)

Recovery Studies: The accuracy of proposed method was checked by recovery studies, by addition of standard drug solution to preanalysed sample solution at three different concentration levels within the range of linearity for both the drugs.

RESULTS AND DISCUSSION:

In methanol, Felodipine exhibits absorption at 362.4 nm. The linearity was observed in concentration range of 10-100 µg/mL. The amount of felodipine estimated by proposed method was in good agreement with the label claim. The low % RSD value indicates that method is accurate. The proposed method is simple, accurate, economical and be used in routine analysis of felodipine from tablet formulation.

ACKNOWLEDGMENT:

The authors are thankful to Emcure Pharmaceutical Industry, Bhosari, Pune for providing the pure drug samples samples and Mr. Pravin Chavhan for kind cooperation. They are also thankful to Shri. T.J. Sawant, Chairman and other office bearers of Jayvant Shikshak Prasarak Mandal for providing necessary facilities.

REFERENCES:

1. The United states Pharmacopoeia, The National Formulary USP 34, NF 29, The United states Pharmacopoeial Convention 12601, Twinbrook Parkway Rockville, Vol. 2, 2011, 2797-2798.

2. Sweetman S.C, Martindale The complete drug reference, 36^th edn, Pharmaceutical press, London, 2009, 1285-1286.

3. Indian Pharmacopoeia, Government of India, Ministry of health and family welfare, 6^th edn, The Indian Pharmacopoeia commission Ghaziabad, vol II, 2011, 1333-1334.

4. Füsun Gedil (Üstün), Osman Üstün, Okan Atay, Quantitative determination of felodipine in pharmaceuticals by high pressure liquid chromatography and UV spectroscopy, Turkish J. Pharm. Sci. 1 (2), 65-76, 2004.

5. Kanakapur A. Basavaiah, Umakanthappa Chandrashekhar and P. Gowda, Titrimetric and spectrophotometric assay of felodipine in tablets using bromate–bromide, Methyl Orange and Indigo carmine reagents, J. Serb. Chem. Soc. 70 (7) 969–978 (2005).

Received on 22.09.2011 Modified on 28.09.2011

Research J. Pharm. and Tech. 4(12): Dec. 2011; Page 1805-1806