A rapid, simple, sensitive and cost effective stability indicating high performance liquid chromato graphic method for the simultaneous determination of rifampicin, isoniazid and pyrazinamide in human plasma was developed and validated in accordance to Food and Drug Administration (FDA) guidelines. The three drugs were eluted under isocratic mode using a 250 × 4.0 mm i.d., 5 µm Phenomenex ODS 2 C18 col umn. The mobile phase was composed of a mixture of acetonitrile, methanol and water in the ratio of 30 : 5 : 65 (v/v, pH adjusted to 5.2) at a flow rate of 1.0 mL/min. The limits of detection and quantification for rifampicin were 0.13 and 0.4 µg/mL, for isoniazid-0.6 and 1.8 µg/mL; and for pyrazinamide-0.5 and 1.6 µg/mL, respectively. The method can be successfully applied for pharmacokinetic, bioavailability or bioequivalence studies of rifampicin, isoniazid and pyrazinamide combination in human subjects.

A simple, precise and stability-indicating RP-HPLC method was developed for simultaneous quantification of oxycodone (OXCD) and naltrexone (NTRX) in combined dosage form. The developed method was validated with respect to precision, linearity, accuracy, robustness, ruggedness, sensitivity and solution stability. The method was developed with ammonium di hydrogen phosphate buffer (pH 5.0) and acetonitrile in a ratio of 55:45 (v/v) as mobile phase at a flow rate of 1.0 mL/minute over Intersil ODS C18 column (250 mm × 4.6 mm×5μ).The UV detection wavelength was fixed at 235 nm. The column temperature was maintained at ambient temperature. The method showed good linearity with correlation coefficient values of 0.9990 and 0.9994 for OXCD and NTRX. The percent recoveries of the two drugs found within the limits of 98.0–102.0%. The LOQ concentrations of OXCD and NTRX are 0.625 μg/ mL and 0.075 μg/mL, respectively. The LOD concentrations of OXCD and NTRX are 0.3125 μg/mL and 0.0375 μg/mL, respectively. According to ICH guidelines forced degradation study was validated.

Objective of the present research work is to develop a sensitive, selective and accurate new RPHPLC method with UV detection and determination for estimation of Nevirapine (NVP)and its impurities in bulk drug. The separation and quantification was achieved with Kromosil C18 isocratic column, (150 mm × 4.6 mm i.d., particle size 3.5 µm, maintained at ambient temperature), HPLC system (Peak LC P7000), a mixture of 20% acetonitrile, 80% buffer (sodium per chlorate) (v/v), at pH of 4.8 and the flow rate was set at 1.0 ml/min. and UV detection at 220 nm. The retention time for NVP, Impurity-A and Impurity-B were found to be 5.5, 7.8, 3.4 min respectively. The method was validated for Linearity, Accuracy, and Precision. The Limit of detection of NVP, Impurity-A and Impurity-B were found to be 0.03, 0.03, 0.03(µg/ml) respectively.

INTRODUCTION Sofosbuvir ( Fig. 1) is a prodrug of 2'-deoxy-2'-fluoro-2'-C-methyl-uridine monophosphate that is phosphorylated intra cellularly to the active triphosphate form, used for the treatment of chronic hepatitis C. The nucleoside triphosphate is a nonobligate chain-terminating analogue of UTP that competes for incorporation at the HCV NS5B polymerase active site. Viral RNA synthesis is inhibited secondary to incorporation of the phosphorylated metabolite into nascent viral RNA by the HCV RNA-dependent RNA polymerase [1]. Velpatasvir (Fig. 1) A simple, precise, accurate and sensitive, isocratic RP-HPLC method has been developed and validated for the estimation of velpatasvir and sofosbuvir in plasma. Method was developed with, Intersil ODS C18 column (250 mm × 4.6 mm × 5 µ), mobile phase mixture of acetonitrile and water having pH of 6.5 in the ratio of (80:20 v/v) at flow rate 1 mL/min. at UV detector wavelength of 240 nm. Mobile phase pH was adjusted with 1 % o-phthalaldehyde (OPA). The retention times are 3.49 min for sofosbuvir and 6.15 min for velpatasvir, Quantitative linearity was obeyed in the concentration range of 0.1 to 0.8 µg/mL for sofosbuvir and 0.025 to 0.2 µg/mL for velpatasvir. The limit of detections are 0.006 µg/mL for sofosbuvir, 0.0017 µg/mL for velpatasvir and limit of quantifications are 0.0125 µg/mL for sofosbuvir, 0.003 µg/mL for velpatasvir for which indicates the sensitivity of the method. The average recovery of sofosbuvir is 100.75 and 99.25 % for velpatasvir. The high percentage recovery indicates that the proposed method is highly accurate. Bench top, Auto sampler, Freeze and Thaw stability test are performed.

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