INTRODUCTION:

Voglibose, a potent α-glucosidase inhibitor is used for the treatment of diabetes mellitus^1,2. It acts as glucosidase inhibitor, remaining active within the gastrointestinal tract of humans by delaying the glucose absorption thereby preventing the sudden surge of glucose in the human body after meals. Most commonly used glucosidase inhibitors include acarbose, mitglitol and voglibose. Voglibose is the safest and most effective of them all^3,4. It is most commonly available in the form of tablets with the dosages of 0.2mg to 0.3mg per tablet. Structure of voglibose (Fig.1) is [5-(1, 3-dihydroxypropane-2-yl -amino)-1-(hydroxymethyl) cyclohexane-1, 2, 3, 4-tetrol] similar to that of carbohydrate. Literature survey reveals various analytical methods reported for estimation of voglibose in API and pharmaceutical formulations includes UV spectrophotometric^5,6 HPLC^7,8, LC-MS⁹ and HPTLC¹⁰.

Spectrophotometry is generally preferred, especially by small-scale industries as the cost of the equipment is less and the maintenance problems are minimal. UV spectrophotometry^11-18 can be used for stress degradation studies of voglibose and its degraded products. The active pharmaceutical ingredient is subjected to a number of forced degradation conditions, including acidic, basic, and oxidative conditions, as per ICH guidelines^19-21. Forced degradation should be one of the activities performed early in the development process to ensure that the method is discriminating before a lot of time, effort, and money have been expended. It is important to determine which conditions are responsible to degrade the drug. This work presents a stability indicating UV spectrophotometric method for estimation of voglibose in tablet formulation, which can be used for its routine analysis in laboratory.

MATERIALS AND METHOD:

An Elico SL244 double beam UV/VIS Spectrophotometer having spectral treats software was employed for all spectrophotometric measurments using 10 mm quartz cells. All weighing’s were done on an electronic balance (SHIMADZU AUX 220). Sonicator was from Citizen India and used for sonication. Glassware used in each procedure were cleaned entirely with detergent and rinsed thoroughly with double-distilled water and dried in a hot air oven. Pure drug sample of voglibose was obtained from Sun Pharmaceutical Industries Limited Mumbai, India. All other chemicals and reagents used were of analytical grade. Sodium hydroxide (NaOH) and hydrochloric acid (HCl) were purchased from Qualigens Chemicals Ltd., Mumbai, India. A commercial tablet of VOLIBO containing 0.3mg voglibose manufactured by Sun Pharmaceutical Industries Limited Mumbai, was procured from local pharmacy.

Preperation of standard solution:

Standard drug solution of voglibose was prepared by dissolving 100mg voglibose in 50ml 0.1 N NaOH. This solution was transferred to 100ml volumetric flask and its volume made up to mark with 0.1 N NaOH to obtain stock solution of 1mg/ml concentration.This solution was further diluted with 0.1 N NaOH to obtain 100 µg.ml.

Preperation of sample solution:

Accurately 20 tablets from were weight individually and average weight was calculated. The tablet powder equivalent to 0.3 mg of voglibose is transfer into a 10 ml volumetric flask. To it little quantity of 0.1N NaOH was added and sonicated for few min. The solution was diluted up to the mark with 0.1N NaOH(30µg/ml). The solution was filtered and pipetted out 5 ml and make up to 10 ml with 0.1N NaOH (15µg/ml) . The absorbance of the resulting solution was measured at 214.5nm against 0.1 N NaOH as blank. The amount of voglibose was calculated from regression equation of calibration plot.

Linearity:

For linearity, aliquots of 0.5-2.5ml portion of stock solutions were transferred to series of 10ml volumetric flasks, and the volume made up to mark with 0.1 N NaOH. Solutions were scanned in the range of 200-400 nm against blank. The absorption maxima values were found at 214.5nm against blank. The calibration curve was plotted. The limit of detection (LOD) and limit of quantitation (LOQ) were separately determined based on standard deviation of the Y-intercept and the slope of the calibration curve. LOD = 3.3 x σ/s, LOQ= 10 x σ/s Where, σ=Standard deviation of y intercept of regression lines, S =Slope of calibration Curve.

Accuracy:

Accuracy of the method was determined by performing the recovery experiment. This experiment was performed at five levels equivalent of 80 to 120% of nominal concentration. Three replicate samples of each concentration level were prepared and the percent recovery at each level was determined.

Precision:

Precision was carried out by performing an inter day variation and Intra day variation. In Inter day variation the sample was analyzed on three consecutive days and intra-day variation the absorbances were measured three times in a day. The percentage relative standard deviation (% RSD) was calculated.

Forced degradation studies:

In forced degradation studies the drug substance undergone acid and base induced degradation, thermal degradation, oxidative and photolytic degradation. Only on thermal degradation studies the solid state of drug was taken where as in remaining degradation conditions the solution was used for forced degradation to provide an indication of the stability-indicating property and specificity of the proposed method. Solutions were prepared by dissolving drug substance in 0.1 N NaOH solution and spectral scan ranges from 200-400nm in UV/Vis spectrophotometer was performed to take absorbance at different days for observing degradation. In all degradation studies, the absorbance of the drug was measured and the amount of degraded drug was calculated. Acid hydrolysis of drug substance in solution state was directed with 0.1 N HCl at 60°C for 8 d. Base hydrolysis of drug substance in solution state was guided by 0.1 N NaOH solution at 60°C for 4 d. For thermal stress, solid samples of drug substance was entrusted in a controlled-temperature oven at 80°C for 4 d. For oxidative degradation the drug substance was exposed with 3 % H₂O₂. Under UV degradation study, suitable aliquot of the stock solution was exposed to UV radiation of 1.4 flux intensity for 48 h in a UV chamber.

RESULTS AND DISCUSSION

Method Validation

The developed method was validated in terms of Linearity, precision, accuracy, Limit of detection (LOD) and Limit of Quantitation (LOQ), robustness and ruggedness

Spectral properties:

The Voglibose solution at 0.1 N NaOH showed an absorbance peak at 214.5nm, respectively, and it was found that the absorbance at these wavelengths was simply dependent on the concentration of the drug. The corresponding blank solution showed the lowest absorbance as shown in Fig. 2.

Linearity:

Five points calibration curve were obtained in a concentration range from 5-25µg/ml for voglibose. The response of the drug was found to be linear in the investigation concentration range and the linear regression equation was y=0.0309x+0.0631 with correlation coefficient 0.999 (Table 1, Fig. 3).

Fig 2: Absorption spectra of voglibose

Fig.3: Calibration curve of voglibose

Table 1: Sensitivity and regression parameters

Parameter	Results
Beer’s Law limit (μg/ml)	5-25
λmax, nm	214.5
Sandell sensitivity, µg/cm²/0.001 AU	0.0823
Molar absorptivity(ε), L/mol/cm^-1	3.25 ×10³
(LOD)Limit of detection µg/mL	0.24
(LOQ)Limit of quantification, µg/mL	0.73
Regression parameters
Slope (m)	0.030
Intercept (b)	0.063
Correlation coefficient (r)	0.999

Precision:

Precision was checked in terms of repeatability, inter and intraday precision. It was expressed in percentage RSD.

Repeatability:

The repeatability was evaluated by assaying six times of sample solution prepared for assay determination. Percentage RSD was found to 0.34 %.

Interday and Intraday precision:

The intraday and interday precision study of atazanavir sulfate was carried out by estimating different concentrations of atazanavir sulfate three times on the same day (intraday precision) and on three different days (interday precision) and the results were reported in terms of Percentage RSD. (Table 2).

Table 2: Interday & Intraday Precision

S. No	Concentration (µg/ml)	Interday		Intraday
S. No	Concentration (µg/ml)	SD	% RSD	SD	%RSD
1	10	0.00057	1.07	0.001	1.72
2	15	0.0025	1.63	0.0015	0.98
3	20	0.003	1.17	0.0026	1.03

Accuracy:

Accuracy was assessed by determination of the recovery of the method by addition of standard drug to the known amount of marketed formulation at three different concentration levels 80, 100 and 120 % taking into consideration percentage purity of added bulk drug samples. Each concentration was analyzed three times and average recoveries were measured (Table 3).

Table 3: Accuracy Studies

Name of Drug	Spiked Level	Conc. Added (μg/ml)	Conc. Recovered (μg/ml)	%Recovery ± SD^*
Voglibose	80%	12	12.02	100.18%±0.0256
	100%	15	14.97	99.84%±0.0582
	120%	18	17.99	99.95%±0.0421

*Average of three determinations

Robustness and ruggedness:

Robustness is determined by the analysis of standard solutions at over 3 wavelengths (λmax and λmax ± 2nm).

Ruggedness was determined by the analysis was performed by two analysts using the same cuvette in the same laboratory. Intermediate% RSD values were < 2%, indicating acceptable robustness and ruggedness. These results are presented in Table 4.

Table 4: Results of robustness and ruggedness

Voglibose taken (µg/mL)	Method robustness (Mean ± %RSD; n=6)		Method ruggedness (Mean ± %RSD; n=6)
15(µg/mL)	Wave length	Absorbance	Analyst 1	Analyst 2
	212.5 nm	0.52 ± 0.36	0.59 ± 0.35	0.61 ± 0.31
	214.5 nm	0.57 ± 0.25
	216.5 nm	0.58 ± 0.22

Limit of Detection (LOD) and Limit of Quantitation (LOQ)

The LOD and LOQ were calculated according to below equation given by

LOD= 3.3 σ/s

LOQ=10 σ/s

Where σ is the standard deviation of y intercepts of regression lines and s is the slope of the calibration curve (Table 1).

Application of method to formulation:

The proposed was applied to pharmaceutical formulation of voglibose tablets (VOLIBO). The % purity was of voglibose was found to in agreement with the labeled claim.

Forced degradation studies:

To develop the stability indicating method, the UV spectrums of voglibose under several stressed condition were studied on UV/Vis spectrophotometer. The % degradation of drug in each conditions were presented in fig 4. From this study, it can be concluded that the drug is showing degradation in all the condition in which it is more prone in thermal and photolytic conditions.

Fig.4: Forced degradation data

CONCLUSIONS:

All of these factors lead to the conclusion that the stability indicating UV spectroscopic method is accurate, precise, simple, sensitive and fast and can be successfully applied to estimation of voglibose without interference using 0.1 NaOH and can be applied in bulk and pharmaceutical formulations. The drug exhibits degradation in all selected condition specially in thermal and photolytic. The relative standard deviation (RSD) for all parameters was found to be less than 2, indicating that the standard of the method was also within limits, so the proposed method could be used for general quantitative estimation of voglibose in bulk and pharmaceutical formulations.

ACKNOWLEDGEMENT:

The authors are grateful to Sun Pharma Ltd for supplying the gift samples of pure drug. The author thanks the Srikrupa Institute of Pharmaceutical Sciences for providing the instrumental and chemical facilities.

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Received on 21.10.2020 Modified on 18.02.2021

Research J. Pharm. and Tech. 2022; 15(6):2543-2546.

DOI: 10.52711/0974-360X.2022.00425