New Analytical Techniques for the Determination of Epalrestat in Pharmaceutical Dosage forms by Spectrophotometry

 

Mukthinuthalapati Mathrusri Annapurna*, Malineni Sushmitha , Kunala Anusha

Department of Pharmaceutical Analysis and Quality Assurance, GITAM Institute of Pharmacy,

GITAM University, Visakhapatnam, India

 

ABSTRACT:

Epalrestat is an aldose reductase inhibitor. Three simple, precise and accurate Spectrophotometric methods have been developed for the determination of Epalrestat in pharmaceutical formulations. Spectrophotometric analysis was performed and linearity was observed over the concentration range 0.1-25, 0.5-20 and 0.5-20 μg/ml in phosphate buffer (pH 5.0), phosphate buffer (pH 7.0) and borate buffer (pH 9.0) respectively. All the three methods were validated and can be used for the determination of Epalrestat in pharmaceutical formulations (Tablets).

 

 

 

INTRODUCTION:

Epalrestat, chemically it is 2- [(5Z)- 5- [(E)- 3-phenil- 2- methylprop- 2- enylidene]- 4-oxo- 2-thioxo- 3- thiazolidinyl] acetic acid with molecular weight 319.41g/mol. Epalrestat is an aldose reductase inhibitor that is approved for the improvement of subjective neuropathy symptoms, abnormality of vibration sense, and abnormal changes in heart beat associated with diabetic peripheral neuropathy. Epalrestat was determined by different analytical techniques such as Spectrophotometry (Sharath, 2013), (Patel Hiral, 2013), (Sharathchandra, 2013), (Patel Chandani, 2014), (Sharath Chandra, 2013), HPLC (Atul, 2012), and UPLC (Sharath Chandra, 2013). In the present study, the authors have developed three simple, rapid and cost-effective UV Spectrophotometric methods analysis of Epalrestat in pharmaceutical formulations in phosphate buffer pH 5.0 (Method A), phosphate buffer pH 7.0 (Method B) and borate buffer pH 9.0 (Method C) and validated as per the ICH guidelines (ICH guidelines, 2005).

 

EXPERIMENTAL:

Instrumentation:

A double beam UV-VIS spectrophotometer (UV-1800, Shimadzu, Japan) connected to computer loaded with spectra manager software UV Probe was employed with spectral bandwidth of 1 nm and wavelength accuracy of ±0.3 nm with a pair of 10 mm matched quartz cells. For scanning, the wavelength range selected was 800 to 200 nm with medium scanning speed. All weights were taken on electronic balance (Shimadzu). 

 

Reagents and Chemicals:

Analytical grade reagents were used. Pure samples of Epalrestat were supplied as gift sample from Micro Labs Ltd., India. Epalrestat is commercially available as tablets and injections with brand name EPAREL ((Label claim: 50.0 mg/tablet, Micro labs Ltd., Bangalore) ALDONIL ((Label claim: 50.0 mg/tablet Zydus Cadila Healthcare Ltd., Gujarat).

 

Preparation of phosphate buffer (pH 5.0) (Method A):

6.8 grams of potassium di hydrogen phosphate was taken in 1000ml of water and adjusted pH to 5.0 with 10M potassium hydroxide.

Preparation of phosphate buffer (pH 7.0) (Method B):

Place 50.0 ml of 0.2 M potassium dihydrogen phosphate in a 200 ml volumetric flask, add 29.1ml of 0.2 M sodium hydroxide and dilute with water to 1000 ml

 

Preparation of borate buffer (pH 9.0) (Method C): Dissolve 6.20 g of boric acid in 500 ml of water, adjust to pH 9.0 with 1M sodium hydroxide (about 41.5 ml) and dilute with water to 1000 ml.

 

Preparation of stock solutions:

Epalrestat stock solution was prepared by dissolving 25 mg of the drug in methanol in 25 ml volumetric flask (1000μg/ml) and further dilutions were made from the stock solution as per the requirement with the reagents mentioned for methods A, B and C respectively.

 

Validation:

Linearity and Range:

A series of Epalrestat solutions were prepared and scanned (200- 400 nm) against their reagent blank. The absorbance of these solutions were noted from their absorption spectrum in all the three methods A, B and C. A calibration curve was plotted respectively by taking the concentration of the solutions on the x-axis and the corresponding absorbance on the y-axis.

 

Accuracy and Precision:

The precision and accuracy studies were performed as per the ICH guidelines. Accuracy was evaluated from the percent recovery studies by the addition of 80%, 100% and 120% of pure sample solution to the pre-analyzed formulation solution. Epalrestat extracted drug solution from the formulation (10μg/mL) was spiked with 80%, 100% and 120% of pure drug solution and the % recovery was calculated. The precision study was done by recording the absorbance of six replicates. The intra-day precision studies were carried out at three different concentration levels (5, 10 and 20 μg/ml) individually on the same day for all the five methods A, B and C respectively and the % RSD was calculated. The inter-day precision study was also performed on three different days i.e. day 1, day 2 and day 3 at three different concentration levels (5, 10 and 20 μg/ml) individually on the same day for all the five methods A, B and C respectively and the % RSD was calculated.

 

Assay for marketed formulations:

Twenty tablets from each brand EPAREL (Micro labs Ltd., Bangalore) ALDONIL (Zydus Cadila Healthcare Ltd., Gujarat) were procured from the local pharmacy store, weighed and powdered. Powder equivalent to 25 mg of Epalrestat was transferred carefully in to a 25ml volumetric flask and extracted with methanol. The filtrate so obtained was diluted further with the respective reagents separately for method A, B and C respectively and the percentage recovery was calculated.

 

RESULTS AND DISCUSSION:

Epalrestat was spectrophotometrically determined by three methods in UV region. It has shown absorption maxima (λ_max) at 387nm in all the three methods A, B and C (Figure 2). The three methods were validated and are as follows.

 

Validation:

Calibration graphs were drawn by taking the concentration of the drug solutions on the x-axis and the corresponding absorbance values on the y-axis for method A, B and C (Figure 3). The linear regression equations were found to be y=0.1115x-0.0062 (R²=0.9992), y=0.1353x-0.0768 (R²=0.9991) and y=0.1436x-0.0894 (R²=0.9994) for method A, B and C respectively. The % RSD in precision studies was found to be less than 2% in all the method A, B and C indicating that the methods are more precise. The % recovery in accuracy studies for all the 3 methods A, B and C were found to be ≤ 97.5 % indicating that the method is more accurate. The _{optical characteristics of Epalrestat} were shown in Table 1. The methods have been applied for the determination of Epalrestat marketed formulations and the percentage recovery was found to be in the range of 99.08-99.15, 98.43-99.25 and 98.49-99.25 for method A, B and C respectively (Table 2) indicating that the proposed methods can be applied for the determination of pharmaceutical formulations successfully.

 

Table 1: Optical characteristics of Epalrestat

 

 

 

 

Table 2: Assay of marketed formulations (Tablets)

*Each value is average of three determinations

 

Fig 1: Chemical structure of Epalrestat

 

Fig 2: Absorption spectra of Epalrestat in Phosphate buffer; pH-5.0 (a), Phosphate buffer; pH-7.0 (b) and Borate buffer; pH-9.0 (c)

 

 

(a)

 

(b)

 

(c)

Fig 3: Calibration curves of Epalrestat in phosphate buffer pH-5.0 [a], phosphate buffer pH- 7.0 [b] and borate buffer pH-9.0 [c]

 

CONCLUSION:

The three Spectrophotometric methods are simple, precise and accurate and are suitable for the determination of Epalrestat in pharmaceutical formulations.

 

ACKNOWLEDGMENT:

The authors are grateful M/s GITAM University for providing necessary research facilities and also to Micro labs Ltd (India) for providing the gift samples of Epalrestat.

REFERENCES:

1.     Atul Arun Shirkhedkar, Chetan Shantaram Nankar, Sanjay Javarilal Surana. Quantitative determination of Epalrestat using reversed phase high-performance liquid-chromatography. Eurasian J. Analytical Chemistry. 7; 2012: 49-55.

2.     International Conference on Harmonization of Technical Requirements for the Registration of Pharmaceutical for Human Use: Validation of Analytical procedures, Text and methodology - Q2 (R1), 2005.

3.     Patel Chandani D, Patel Rajan J, Shah Shruti S, Mardia RB, Chauhan SP, Suhagia BN. Simultaneous estimation of Epalrestat and methylcobalamin in bulk and tablet formulation by UV spectrophotometery and liquid chromatography. Indo American J. Pharm. Sci.  4; 2014: 2650-2656.

4.     Patel Hiral M, Shaikh Farhatjahan, Bharucha Rinal, Kachhadiya Kruti. Development and validation of analytical methods for estimation of Epalrestat and Methylcobalamin in bulk and in tablet dosage by absorption ratio method. Inventi Rapid: Pharma Analysis and Quality Assurance. 2013, Inventi:ppaqa/841/13.

5.     Sharath Chandra Seelam, Dhana Lakshmi K, Nagarjuna Reddy G, Sreenivasa. Analytical method validation of Epalrestat an antidiabetic drug in bulk and tablet formulations by UPLC - A novel technique. Indo American Journal of Pharmaceutical Research. 3; 2013: 5479-5187.

6.     Sharath Chandra Seelam, Swarna Mayuri R, Priyanka G, Priyanka M, Nidhi NK. UV Spectrophotometric methods for estimation of Epalrestat in bulk and dosage forms by difference and area under curve methods. Indo American J. Pharmaceutical Research. 3; 2013: 5134-5140.

7.     Sharath Chandra. Seelam, Dhanalakshmi K, Nagarjuna Reddy. New derivative Spectrophotometric methods for the determination of Epalrestat – an antidiabetic drug. Int. J. Pharm. Sci. Rev. Res. 21; 2013: 247-250.

8.     Sharathchandra Seelam, Dhanalakshmi K. Nagarjuna Reddy G. Validation of derivative Spectrophotometric and UPLC methods for Quantitative determination of Epalrestat in bulk and pharmaceutical dosage form. International J. Pharmacy and Pharmaceutical Sci. 5; 2013: 341-346.

 

 

Accepted on 20.03.2017           © RJPT All right reserved