Development and Validation of UV-Spectrophotometric Method for Gabapentin in Bulk Drug and Formulation.

 

Sampada D. Dalvi*, Pramod H. Sakpal and Pramod L. Ingale

Marathwada Mitra Mandal’s College of Pharmacy, Sr.No. 4/17, Sector No. 34, PCNTDA, Off Kalewadi Phata-Pimpri Road, Thergoan (Kalewadi) Pune – 411033.

*Corresponding Author E-mail: pawar_sampada@rediffmail.com.

 

ABSTRACT:

A simple, rapid and sensitive spectrophotometric method has been developed for determination of Gabapentin in bulk drug and its dosage form. The method is based on diazotization and coupling reaction of the drug with β-naphthal solution to produce an intense red colored complex exhibiting maximum absorbance at 558 nm. The calibration graph is linear over the range of 10- 50µg/ml for the drug with correlation coefficient (n=6) of 0.997. The various parameters affecting the development and stability of color product were carefully studied and optimized. The proposed method was successfully applied to determine the drug in formulation. The result obtained of this method were in good agreement recommended for the quality control and routine analysis where time, cost effectiveness and high specificity of analytical techniques are of great importance.

 

KEYWORDS: Gabapentin, UV, β-naphthol, standard curve method, Recovery studies

 


 

INTRODUCTION:

Gabapentin is Anticovulsant drug. It is use as an adjunctive medication to control partial seizures (effective when added to other antiseizure drugs) and for treating postherpetic neuralgia. Chemically it is 1 – (amino methyl) cyclohexane acetic acid hydrochloride. It is not official in USP, BP and IP) the molecular formula of gabapentin hydrochloride is C9H18ClNO2. The molecular weight of gabapentin hydrochloride is 207.70 with CAS Registry number 60142 – 96 – 3. Different analytical instruments such as HPLC(1-2), LC–MS(3-4), GC–MS(5), GC(6), Capillary Electrophoresis(7) are available for quantitative analysis of intermediates of different bulk drugs, the cost of these instrument are very high. Also one UV(8) method requiring long and tedious pretreatment of samples and laborious procedures is available. The present paper describes a simple, rapid, accurate and responsible method for the estimation of gabapentin in bulk drug and formulation.

 

MATERIAL AND METHOD:

Apparatus:

The UV spectra of standard and sample solutions were recorded in 1 cm quartz cells using a Shimadzu UV/Vis-1800 double beam UV/Vis spectrophotometer (Japan). Shimadzu AUX 220 balance was used for weighing the samples

 

Reagents

Gabapentin was gift sample from Lupin Pharmaceuticals. All reagent used were of analytical grade.

 

Preparation of standard stock solution:

Weighed 100 mg of pure Gabapentin accurately and transferred to 100 ml volumetric flask. Drug was dissolved in 1N HCL. The conc. of drug was 1mg/ml.10ml of this solution was taken in 100ml volumetric flask, to this add 5% NaNO2 and 1% β-Naphthol and volume was made up to mark with distilled water. The reaction was allowed to proceed at room temperature and absorbance was measured at 558 nm (Fig. 1) against the reagent blank prepared simultaneously. The calibration curve was constructed by plotting the absorbance against the initial concentration of gabapentin hydrochloride (Fig. 2). The content of gabapentin hydrochloride is calculated from the calibration curve.

 

Procedure for analysis of tablet formulation:               

Tablet was procured from local market and average weight was determined. The powder equivalent to 100 mg of gabapentin was weighed accurately and dissolved in 100 ml 0.1 N HCl, shaken for 10 min and filtered. 10 ml of this solution was taken in 100ml volumetric flask to this add 10ml 5% NaNO2 and add 10ml 1% β-Naphthol reagent volume was made up to 100 ml with distilled water from this solution 2 ml was diluted to 10ml  with distilled water . Absorbance of solution was measured at 558nm against distilled water. The conc. Found from calibration curve method.

 

Fig no: 1. Spectra for Gabapentin

 

Table No. 1   Calibration table for Gabapentin at 558 nm.

Sr. no.

Conc. ( µg/ml

Abs at 558 nm

1

10

0.296

2

15

0.413

3

20

0.569

4

25

0.691

5

30

0.839

6

35

0.958

7

40

1.14

8

45

1.1223

9

50

1.321

 

Method Validation:

Method validation is closely related to method development. When a new method is being developed, some parameters are already being evaluated during the ‘development stage’ while in fact this forms part of the ‘validation stage’. The ICH guidelines achieved a great deal in harmonizing the definitions of required validation parameters, their calculation and interpretation. The international conference on the Harmonization of the Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) has harmonized the requirements in two guidelines (9-10). The first one summarizes and defines the validation characteristics needed for various types of test procedures, the second one extends the previous test to include the experimental data required and some statistical interpretation. Various parameters, concentration of reagents, stability of complex etc were studied.

 

Fig: 2. Calibration curve for Gabapentin at 558 nm Procedure for analysis of tablet formulation  

 

The specificity of the method to determine accurately the analyte of interest in the presence of other components. The sensitivity of the method was determined with respect to limit of detection (LOD) and limit of quantification (LOQ). The LOD was calculated as 3 times the noise level and LOQ was calculated as 10 times the noise level. Recovery studies were done at three different levels


 

Table No. 2: - Recovery study of Gabapentin at 558 nm: -

Name of drug

 Level of Percentage Recovery

Conc. Used

µg/ml

Conc. added

µg/ml

Conc. Found µg/ml at 558nm

%  Found at 558nm

Gabapentin

80

36

8

37.26923

103.5256

80

36

8

37.46154

104.0598

80

36

8

37.61538

104.4872

100

40

10

40.03846

100.0962

100

40

10

40.26923

100.6731

100

40

10

39.76923

99.42308

120

44

12

44.07692

100.1748

120

44

12

45.34615

103.0594

120

44

12

47.46154

107.4301

 

Table No.3  Statistical Parameters:-

Component

Percentage

Mean

Standard Deviation

Percentage Relative Standard Deviation

Standard Error

Precision study of Gabapentin at 558 nm

100%

100.7692

1.2644

1.2644

0.522

 

 


RESULTS AND DISCUSSION:

Under the established conditions, Gabapentin showed good correlation with Beer's law over the concentration range from 5 - 50 µg/mL at excitation wavelengths 558nm. The linearity was shown in the concentration range of 5 - 50 µg/mL (y = 0.026 x -0.021 and correlation coefficient r2 =0.997(Table 1). A relative standard deviation of 1.2644 % was observed on analysis of six replicate samples. Results of recovery studies demonstrated that the proposed method at 558nm was highly accurate (Table 2). Both inter-day as well as intra-day precisions were carried out in different concentration of the solutions and the relative standard deviation (%RSD) was found to be less than 2.0 (Table 3). Limit of detection and limit of quantification at 558nm was found to be 1.604 and 4.863 µg/mL, respectively. Results obtained confirmed ruggedness of the method. The proposed method was validated with respect to linearity, sensitivity, accuracy, reproducibility and precision.

 

CONCLUSION:

The colorimetric method attempted for the estimation of Gabapentin in bulk drug and dosage form. As Gabapentin does not absorbances in UV region in any solvent it was necessary to derivatise Gabapentin to form colored complex having λ max in visible region. The colorimetric method for analysis of Gabapentin is based on complexation of drug with different reagent was   attempted or the estimation of Gabapentin in bulk drug and dosage form. The proposed method was found to yield reproducible result for bulk and dosage forms. The recovery studies for the method were found to be satisfactory and can be used for the routine quality control analysis. So the proposed method can be used for the routine quality control analysis of the bulk drug as well as formulation.

 

ACKNOWLEDGEMENTS:

The authors thank the Lupin Pharmaceutical Pvt Ltd., for providing gift sample of Gabapentin. Thanks are also due to the principal, Dr. M. J. Patil, for providing infrastructure facilities.

 

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Received on 04.06.2011        Modified on 21.07.2011

Accepted on 14.08.2011        © AJRC All right reserved

Asian J. Research Chem. 4(10): Oct., 2011; Page 1526-1528