Method Development and Validation for the Estimation of Darunavir in Rat Plasma by RP-HPLC

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1 World Journal of Pharmaceutical Sciences ISSN (Print): ; ISSN (Online): Published by Atom and Cell Publishers All Rights Reserved Available online at: Original Article Method Development and Validation for the Estimation of Darunavir in Rat Plasma by RP-HPLC Varaprasad Adepu 1 *, Nagoji K.E.V 2, Girijasastry Vedula 3 * 1 Research scholar, Department of pharmacy, JNTUK University, Kakinada, AP Department of Pharmaceutical Analysis, Srivenkateswara College of Pharmacy, Srikakulam, AP Department of Pharmaceutical Chemistry, Andhra University, Visakhapatnam, A.P, India ABSTRACT Received: / Revised: / Accepted: / Published: The proposed research work is a simple precise, accurate, selective RP-HPLC method was developed and validated for the quantitative of estimation of darunavir. Sample preparation was performed by liquid-liquid extraction in ethyl acetate. Darunavir was extracted from rat plasma and HPLC analysis was performed using Waters 515 Series pumps combined with a Waters PDA 2998 series photo diode array detector (DAD). The column used was Agilent C18 column (150mm 4.6mm, particle size 5-micron Agilent, USA). Analysis was isocratic at 1.0 ml/min flow rate with ACN: Tri ethyl amine (0.025M Potassium buffer ph 2.3 (70:30, v/v) as mobile phase. The mobile phase was premixed, filtered through a 0.2 μm nylon membrane filter to remove any particulate matter and degassed by sonication before use. The elution was detected at 210 nm. Each solution was injected in triplicate, and the relative standard deviation (R.S.D.) was measured. The retention times of darunavir 2.24 min. The method was validated over the range of μg/ml. The limit of detection was 0.06μg/ml and the limit of quantification was 0.193μg/ml. Inter-day as well intra-day replicates of darunavir, gave % R.S.D. below 2.07 and respectively The absolute recovery of Darunavir was greater than 90% were achieved. This RP-HPLC method was applied for determination of Darunavir in plasma. Key Words: RP-HPLC, Darunavir, Plasma Extraction, PDA Detection. INTRODUCTION Darunavir is an inhibitor of the human immunodeficiency virus (HIV-1) protease. Chemically it is [(1S,2R)-3-[[(4- aminophenyl)sulfonyl](2-methylpropyl)amino]-2- hydroxy-1- (phenylmethyl)propyl]-carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester monoethanolate 1-2. Its molecular formula is C 27H 37N 3O 7S and its molecular weight is Darunavir ethanolate has the following structural formula. Few analytical methods were reported in the literature, such as determination of darunavir in pharmaceutical formulations 3-5. However literature survey reveals that, there is no method for the estimation of darunavir in rat plasma by reversed phase-hplc. Chemical structure of Darunavir, Fig.1 Chemical structure of Darunavir MATERIALS AND METHODS Chemicals and Reagents: An analytically pure sample of Darunavir was obtained as a gift sample from Dr.reddys Labs Pvt. Ltd., Hyderabad, India. High purity water was prepared by using Millipore Milli-Q plus water purification system. HPLC grade acetonitrile was procured from Loba Chemie. *Corresponding Author Address: Mr. Varaprasad Adepu, Research scholar, Department of pharmacy, JNTUK, Kakinada, AP , India; id: varaprasadadepuv@rediffmail.com

2 Instrumentation: Waters 2695 system with PDA detector equipped with Empower-2 software; phenomenex C 18 column((250 x 4.6 mm, 5 μm particle size) was used for method development, double-beam Perkin Elmer (LAMBDA 25) UV-Vis spectrophotometer was used for spectral measurements and ELICO ph meter was used for ph measurements. volumetric flask, add 10 ml of methanol sonicate it, adjust the volume with methanol. Solutions were stored at 2-8 ºC was used to spike plasma samples. Standards and quality control samples were made by addition of the determined quantity of stock solution to drug free plasma and stored at -20 ºC in aliquots. Plasma quality control sample concentrations were 5, 10 and 20 µg/ml. Chromatographic conditions: The separation of darunavir was achieved on a reversed phase C18 column with a mobile phase consisting of 10 mm ammonium acetate: acetonitrile: TEA in the ratio 70:30 % (v/v). Quantitation of darunavir was performed by PDA detection at 210 nm, at CTO 40 ºC and flow 1.0 ml/min. Standard and stock solution preparation: Stock solution of darunavir prepared in methanol (1000 ppm), weigh 25 mg of darunavir transfer to Preparation of plasma samples: Take 0.5 ml of plasma in vial, add 100 μl of 0.1 N HCl, vortex the vials on vortexer, then add 3 ml of ethyl acetate, vortex vials for 3 min on vortexer, then centrifuge the vial in cold centrifuge for 10 min at 4500 rpm on 4 ºC. Separate 2 ml of upper layer of organic solvent in vial, evaporate to dryness at 50 ºC under a steady stream of nitrogen. Following reconstitution of the residue in 100 μl of mobile phase, the mixture was transferred to a micro insert and 60 μl was then injected on to HPLC. Fig 2 Typical chromatogram obtained from standard solution Fig.3 Typical chromatogram of Darunavir in Plasma 491

3 Calibration and linearity: Standard curve were constructed using seven standards non-zero concentrations in plasma and run in duplicate daily for three consecutive days. Drug concentrations were reported as the area of drug. In plasma the standard concentrations range for 1.5 to 3.5 µg/ml. Calibration curves were generated using weighted least squares regression analysis and obtained over the respective standard concentrations in plasma. All standards and quality control samples were stored at -20 ºC until analysis. Fig 4 Calibration curve of Darunavir Fig 5 Overlain chromatogram of Darunavir in Plasma 492

4 Table 1 Linearity data S.NO Concentration Peak (µg/ml) area r Precision and accuracy: Standards and replicate quality control samples of plasma at each concentration were analyzed on three consecutive days, after, which inter-and intra-day means, % nominal and coefficients of variation (% CV) were calculated by standard method. Validation parameters: Validation parameters are tested according to guidelines for the proposed method. Stability of darunavir was evaluated according to the freeze thaw cycle, refrigerator (holding time) and auto sampler stability. In FTC test plasma samples was stored in -20ºC temperature. Samples were taken out from the deep freezer and equilibrated to room Temperature and analyzed. The results were compared with fresh CC samples. Refrigerator stability of darunavir in plasma was evaluated in spiked samples. Samples were taken out from refrigerator after 5 days and equilibrate to room temperature and analyzed. The results were comparing with fresh CC samples. Auto sampler stability of darunavir in the reconstituted plasma samples were evaluated for 36 h. The calibration curve consists of seven concentration levels of spiked standards of lower limit of detection 5 µg/ml. There solutions were calculated in 1/C weighted condition. The linear calibration curve between the area and the concentration of the target darunavir was established by linear regression. The limit of detection values were calculated by using a signalto-noise ratio of 3.2, while limit of quantification value was calculated by using a signal-to-noise ratio of 10. To assess intra-day precision, six spiked samples at three concentration levels quality control samples were prepared and analyzed. Recovery experiments were performed by comparing the analytical results of extracted standard samples with plasma samples. This experiment was performed on quality control samples. Table 2.Accuarcy results % concentration ( at specific level) Labelled amount (mg) Amount Recovered (mg) (n=6) % Recovery RESULTS AND DISCUSSION Validation study of Darunavir: The Method validation was performed as per ICH guidelines for the simultaneous estimation of Darunavir in rat plasma. The method was validated with respect to parameters including accuracy, precision, linearity, robustness, specificity, system suitability, LOD and LOQ [14]. Specificity: The specificity of the proposed method was established by injecting the placebo and mobile phase solution in triplicate and the chromatograms were recorded. Comparison of chromatograms revealed that there were no interactions between the placebo and sample peaks. Finally, it was indicated that the method was specific. Accuracy: The accuracy was determined by calculating the recovery of Metronidazole, Clindamycin and Darunavir at 50, 100, & 150% and they were added to pre quantified sample solution. The recovery studies were carried out in the dosage form in triplicate each in the presence of placebo. The mean percentage recovery of darunavir at each level was not less than 99%, and not more than 102%. The percentage recovery of Darunavir was found to be in the range of 99 to 100. Selectivity: Selectivity of the method was demonstrated by the absence of endogenous interfering peaks at the retention times of drug in six different lots of extracted blank plasma. Representative chromatographs of extracted blank plasma, extracted plasma samples containing 20 ng/ml of darunavir are given in Figs. 1, 2a and 2b. 493

5 Linearity and lower limit of detection: The peak area of calibration standards was proportional to the concentration of analyte in each assay over the nominal concentration range of 1.5 to 3.5 µg/ml for darunavir. The calibration curves appeared linear and were well described by least squares lines. A weighting factor of 1/X concentration was chosen to achieve homogeneity of variance. The correlation coefficients were = 0.99 (n = 4) for darunavir. The mean (± S.D.) slopes of the calibration curves (n = 4) for darunavir were (± ). Results of four representative standard curve for HPLC determination of darunavir are given in Table-1. The lower imit of quantification for darunavir proved to be 20 µg/ml. Precision: Intra-batch and inter-batch precision and accuracy of the method for darunavir are presented in Tables 2 and 3. The precision deviation values for intra-batch and inter-batch are all within 15 % of the relative standard deviation (RSD) at each quality control level. The accuracy deviation values for intra-batch and inter-batch are all within the (100 ± 15) % of the actual values at each quality control level Sensitivity: Limit of detection (LOD) and limit of quantification (LOQ) were estimated from the signal-to-noise ratio. The LOD was defined as the concentration level corresponding to peak area of three times the baseline noise. The LOQ was defined as the lowest concentration level of a peak area with a signal-to-noise ratio higher than 10. LOD and LOQ values were found to be and µg/ml respectively. Reproducibility (Ruggedness): Ruggedness study was performed to establish the degree of reproducibility of test results obtained by the REFERENCES analysis of the same samples under a variety of normal test conditions. In ruggedness study of the proposed method in rat plasma performed by two different analysts on two different days. % Recovery with SD and % RSD for plasma was calculated. Table 3.System suitability S.No Parameter Results Darunavir 1. Retention time (Min) Resolution Number of Theoretical Plates 4. Tailing Factor 1.3 CONCLUSION Validated RP-HPLC method for the Estimation of Darunavir in rat plasma was established.. The method is simple, accurate, linear, sensitive and reproducible as well as economical for the effective quantitative analysis of darunavir in rat plasma. The method was validated and all the method validation parameters were tested and shown to produce satisfactory results. The method is free from interactions of the other ingredients and excipients used in rat plasma. Finally, concluded that the method is suitable for use in the routine quality control analysis of Darunavir in active pharmaceutical ingredients and in pharmaceutical dosage forms. Acknowledgment: Authors are thankful to Jyothishmathi Institute of pharmaceutical sciences, Ramkrishna colony, Karimnagar, for providing necessary Lab facilities and also thankful to school of Pharmacy, JNTUK Kakinada, for their help and support. 1. Drug bank. Darunavir DB01264 (Accessed december, 2015). 2. FDA Guidance for Industry; Bioanalytical Methods Validation for Human Studies, Center for Drug Evaluation and Research, US Department of Health and Human Services, Rockville, MD (2001). 3. Krishnaiah YSR et al. Reverse phase HPLC method for the estimation of Selegiline hydrochloride in pharmaceutical dosage forms. Asian Journal of Chemistry 2003; 15(3, 4): Ramesh, Bokka et al. HPTLC method for determination of Darunavir in rat plasma and its application in pharmacokinetic studies, Journal of Liquid Chromatography & Related Technologies, 36(2), 2013, Kiado A et al. A simple and sensitive HPTLC method for quantitative analysis of Darunavir ethanolate tablets, Journal of Planar Chromatography - Modern TLC, 24(3), 2011, ICH Q2 (R1); Validation of Analytical Procedures: Text and Methodology International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human use, 7. ICH Harmonized Tripartite Guideline, International Conference on Harmonization ICH Q1A (R2), Stability Testing of NewDrug Substance and Product