DEVELOPMENT AND VALIDATION OF STABILITY INDICATING METHOD FOR THE SIMULTANEOUS ESTIMATION OF ELBASVIR AND GRAZOPREVIRIN PHARMA-CEUTICAL DOSAGE FORMS BY RP-HPLC

DEVELOPMENT AND VALIDATION OF STABILITY INDICATING METHOD FOR THE SIMULTANEOUS ESTIMATION OF ELBASVIR AND GRAZOPREVIRIN PHARMA-CEUTICAL DOSAGE FORMS BY RP-HPLC

Gorja Ashok ^{* 1} and Sumanta Mondal ²

Department of Pharmaceutical Analysis and Quality Assurance ¹, Faculty of Pharmacy, Gland Institute of Pharmaceutical Sciences, Kothapet, Medak - 502313, Telangana, India.

Department of Pharmaceutical Chemistry ², Faculty of Pharmacy, GITAM Institute of Pharmacy,  GITAM  University, Rushikonda, Visakhapatnam - 530045, Andhra Pradesh, India.

ABSTRACT: The present study aimed to develop and validate stability indicating method for the simultaneous determination of Elbasvir and Grazoprevir in its pharmaceutical dosage form using RP-HPLC. Chromatographic separation was done with Discovery C18 (250 mm × 4.6 mm, 5 µ) column using 0.1% ortho-phosphoric acid (OPA) and acetonitrile in the ratio 50:50% v/v as mobile phase on isocratic mode. The column oven temperature was maintained at 30 ºC with a flow rate 1.0 ml/min and components were detected at a wavelength of 315 nm. The retention times for Elbasvir and Grazoprevir was found to be 2.24 min and 3.21 min respectively. The developed method was validated according to ICH guidelines. A good linearity response was observed in the concentration range of 12.5 µg/ml - 75 µg/ml for Elbasvir and 25 µg/ml - 150 µg/ml for Grazoprevir with correlation coefficient of 0.999 for both the drugs. The method was found to be accurate, precise, specific, rugged and robust. The drugs were subjected to stress conditions for testing their stability and found to be stable, with net degradation was within the limits.

Elbasvir, Grazoprevir, RP-HPLC, Method development, Validation, Stability indicating method

INTRODUCTION: Elbasvir Fig. 1A, chemically designated as Dimethyl N,N’-([(6S)-6H-indolo[1,2-c][1,3]benzoxazine-3, 10-diyl] bis{1H- imidazole-5,2-diyl-(2S)-pyrrolidine-2, 1-diyl[(2S)- 1- oxo- 3-methylbutane-1,2-diyl]})biscarbamate, is a white to off-white crystalline solid belonging to antiviral category. It is practically insoluble in water and very slightly soluble in ethanol, but is very soluble in ethyl acetate and acetone and has pKa values of 5.39 and 12.42.

It is used in the treatment of chronic hepatitis C infection ^{1 - 3}. Grazoprevir Fig. 1B, chemically designated as (1R,18R,20R,24S,27S)-N-{(1R,2S)-1-[(cyclopropylsulfonyl) carbamoyl]- 2- vinylcyclo-propyl}- 7- methoxy- 24- (2-methyl-2-propanyl)-22,25-dioxo-2,21-dioxa-4, 11, 23, 26-tetraazapenta-cyclo[24.2.1.03,12.05,10.0,18,20]nonacosa-3,5,7,9, 11-pentaene-27-carboxamide, is white crystalline solid belonging to antiviral category. It is practically insoluble in water but freely soluble in ethanol and has a pKa value of 5.31. It is used in the treatment of chronic hepatitis C infection ^{4 - 6}. According to literature survey, very few methods such as two RP-HPLC methods ^{7, 8} and one LC-MS/MS ⁹ were developed for the simultaneous estimation of Elbasvir and Grazoprevir in pharmaceutical dosage form.

The present study aimed to develop and validate a stability indicating RP-HPLC method for the simultaneous determination of Elbasvir and Grazoprevir in their tablet dosage form.

FIG. 1A: CHEMICAL STRUCTURE OF ELBASVIR                 

FIG. 1B: CHEMICAL STRUCTURE OF GRAZOPREVIR

MATERIAL AND METHODS:

Reagents and Chemicals: Elbasvir and Grazoprevir working standards were supplied as gift samples by spectrum labs, Hyderabad (India). Elbasvir and Grazoprevir (Zepatier) tablets were purchased from local pharmacy. All the solvents used for the method were of HPLC grade and chemicals were of AR grade.

Instrument and Analytical Conditions: Waters HPLC 2998 model equipped with an auto sampler, Discovery C18 (250 mm × 4.6 mm, 5 µ) column, PDA detection and running on empower 2 software was used for chromatographic separation. An isocratic mode with 0.1% ortho-phosphoric acid and acetonitrile in the ratio 50:50% v/v was used as mobile phase. The detection was done at 315 nm at a flow rate of 1.0 ml/min. The other instruments used were pH meter (EI), Digital Balance (Infra Instruments), Ultrasonic Bath (Wadegati), Hot air oven (Cisco).

Preparation of Mobile Phase: 0.1% OPA buffer was prepared by diluting 1 ml of OPA in 1000 ml of distilled water. Mixture of buffer and acetonitrile in the ratio 50:50% v/v respectively makes mobile phase.

Preparation of Diluent: For the preparation of diluent, water and acetonitrile in the ratio 50:50% v/v were mixed respectively.

Preparation of Standard and Sample Solution: Dissolve 5 mg of Elbasvir standard and 10 mg of Grazoprevir standard in 10 ml of diluent. Dilute 1 ml of the above stock solution to 10 ml with diluent. (50 µg/mL Elbasvir and 100 µg/mL Grazoprevir).

Accurately weigh an amount equivalent to 5 mg of Elbasvir from the powdered tablet dosage form (Zepatier) and dissolve in 10 ml of diluent. Filter the above solution and pipette out 1 ml and make up the volume to 10 ml with diluent.

Method Validation: The developed method was validated as per ICH guidelines ¹⁰. The following parameters were validated; accuracy, precision, linearity, specificity, ruggedness, robustness and stability. Forced degradation studies were also conducted by exposing the drugs solution to various conditions such as acidic, basic, peroxide, thermal, neutral and photolytic conditions.

RESULTS AND DISCUSSION: For the development of the method, initially many mobile phase ratios at different flow rates were tried to elute the drugs. Mixture of 0.1% OPA and Acetonitrile in the ratio 50:50% v/v at 1.0 ml/min in isocratic mode was selected as mobile phase based on peak parameters. Discovery C18 (250 mm × 4.6 mm, 5 µ) column was used for separating the drugs. The column oven temperature was maintained at 30 ºC. From the Overlay, suitable wavelength considered for monitoring the drugs was 315 nm as shown in the Fig. 2.

The prepared standard and sample solutions were injected in the chromatographic system and system suitability and % assay were calculated. The standard, sample and blank chromatograms were shown in Fig. 3, 4 and 5 respectively.

FIG. 2: OVERLAY UV SPECTRUM OF ELBASVIR AND GRAZOPREVIR                            

FIG. 3: STANDARD CHROMATOGRAM

FIG. 4: SAMPLE CHROMATOGRAM                                  

FIG. 5: BLANK CHROMATOGRAM

The developed method was validated with the validation parameters. Linearity of the method was determined by preparing the serial dilutions of the standard solution in the concentration range of 12.5 µg/ml - 75 µg/ml and 25 µg/ml - 150 µg/ml for Elbasvir and Grazoprevir respectively.

A graph was plotted between peak areas and concentration for both the drugs, where correlation coefficient was found to be 0.9998 for Elbasvir and 0.9997 for Grazoprevir, indicating that the method obeys Beer’s law. The linearity plots were shown in the Fig. 6A and 6B.

TABLE 1: SYSTEM SUITABILITY AND VALIDATION PARAMETER RESULTS

FIG. 6A: LINEARITY PLOT OF ELBASVIR                  

FIG. 6B: LINEARITY PLOT OF GRAZOPREVIR

The % relative standard deviation (% RSD) for Elbasvir was found to be 0.8 and for Grazoprevir was found to be 0.8, indicates that the method is precise. The % recovery for Elbasvir was found to be 99.90% - 100.53% and for Grazoprevir was found to be 99.48% - 100.00%, indicates that the method is accurate. Method was found to be specific as there is no interference of excipients with the retention time of both the drugs. The placebo chromatogram was shown in the Fig. 7. The method was found to be rugged and robust. The standard drugs were subjected to forced degradation conditions in order to check the stability of the drugs. The drugs were found to be stable as the degradation of drugs at various stress conditions was within the net degradation limits. The forced degradation study results and chromatograms were shown in Table 2 and Fig. 8 respectively.

FIG. 7: PLACEBO CHROMATOGRAM

TABLE 2: RESULT OF FORCED DEGRADATION STUDIES

FIG. 8A: ACID DEGRADATION CHROMATOGRAM              

FIG. 8B: BASE DEGRADATION CHROMATOGRAM

FIG. 8C: PEROXIDE DEGRADATION CHROMATOGRAM          

FIG. 8D: WATER STRESS STUDY CHROMATOGRAM

FIG. 8E: PHOTO STABILITY DEGRADATION CHROMATOGRAM                          

FIG. 8F: DRY HEAT STUDY CHROMATOGRAM              

CONCLUSION: Stability indicating method was developed for the simultaneous determination of Elbasvir and Grazoprevir in tablet dosage form using RP-HPLC. The developed method was validated and was accurate, precise, specific, linear, rugged, robust and stable. The forced degradation studies concluded that the drugs were stable at forced degradation conditions. This method is applicable for the simultaneous determination of Elbasvir and Grazoprevir in its dosage form for routine analysis.

ACKNOWLEDGEMENT: The authors are thankful to the spectrum labs, Hyderabad (India) for providing the drug samples as well as for providing the facilities to carry out the research work.

CONFLICT OF INTEREST: Nil

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    How to cite this article:

    Ashok G and Mondal S: Development and validation of stability indicating method for the simultaneous estimation of Elbasvir and Grazoprevirin pharmaceutical dosage forms by RP-HPLC. Int J Pharm Sci Res 2018; 9(7): 2842-46. doi: 10.13040/IJPSR.0975-8232.9(7). 2842-46.

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