D. Gowri Sankar

A stability indicating reverse phase High performance liquid chromatography (RP-HPLC) method has been developed and subsequently validated for the simultaneous determination of Atazanavir and Cobicistat in bulk and pharmaceutical formulation. Separation was achieved in isocratic mode with a Kinetex C18 100 A (250 mm x 4.6 mm,  5µ) column and mixture consisting of 0.1% OPA(pH 3) and methanol in 80:20 v/v was used as mobile phase with a flow rate of 1 ml/min, column temperature at 25°C and the run time as 10 mins. UV detection was performed at 239 nm and the sample temperature was maintained ambient. The described method for simultaneous determination of Atazanavir and Cobicistat is linear over a range of 8 μg/ml to 120 μg/ml and 5 μg/ml to 60 μg/ml respectively. The method shows good precision results which were below 2.0%RSD. Limit of Detection (LOD) and Limit of Quantification (LOQ) of Atazanavir and Cobicistat was established and found to be 1.49 and 4.97 μg/ml and 1.13 and 3.77 μg/ ml respectively. The developed method was validated according to ICH guidelines for various parameters.The method is simple, rapid, selective and stability indicating method which would be used for regular stability indicating quality control determinations.

An accurate, precise and reproducible RP-HPLC method for the simultaneous determination of Lamivudine and Raltegravir in the bulk API dosage form has been developed and validated. Chromatographic separation was carried out on Agilent C18 (100×4.6mm, 3.5u particle size) column using mobile phase composed of phosphate buffer (PH3.0): acetonitrile (ACN) in ratio 60:40 at a flow rate of 0.8ml/min. The analyte was monitored using DAD detector at 231nm. The retention times were found to be 1.12 and 4.08 for Lamivudine and Raltegravir respectively. The linearity for each were found in the range 10-60µg/ml and their regression values are 0.998 and 0.999 respectively. The developed method was validated as per ICH guidelines.

A simple and precise stability indicating RP-HPLC method was developed and validated for the simultaneous determination of Hydrochlorothiazide (HCTZ) and Nebivolol Hydrochloride (NBV) inbulk and Pharmaceutical dosage forms. Chromatography was carried out on Thermo Hypersil BDS C 18 (150 x 4.6 mm, 5mparticle size) column using a mobile phase of phosphate buffer (adjusted to pH 6.5 with dilute orthophosphoric acid): acetonitrile (40:60% v/v) at a flow rate of 0.8 ml/min. The analyte was monitored using PDA detector at 282 nm. The retention time was found to be2.4 min and 4.0min for Hydrochlorothiazide and Nebivolol Hydrochloride respectively. The proposed method was found to be having linearity in the concentration range of 6.25-37.5 µg/ml for Hydrochlorothiazide (r2 0.9999) and 2.5-15 µg/ml for Nebivolol Hydrochloride (r2 0.9999) respectively. The mean % recoveries obtained were found to be 99.93 % for Hydrochlorothiazide and 100.03% for Nebivolol Hydrochloride respectively. Stress testing which covered acid, alkali, peroxide, photolytic and thermal degradation was performed on under test to prove the specificity of the method and the degradation was achieved. The developed method has been statistically validated according to ICH guide lines and found to be simple, precise and accurate with the prescribed values. Thus the proposed method was successfully applied for the stability indicating simultaneous determination of Hydrochlorothiazide and Nebivolol Hydrochloridein bulk and Pharmaceutical formulations and in routine quality control analysis.

A simple, rapid and specific RP-HPLC method has been developed and validated for determination of Carvedilol in bulk and tablet formulations. Chromatographic separation was performed by Phenomenex Luna C-18 (250 x 4.6mm, 5μm particle size) column with a mobile phase consisting of a mixture of phosphate buffer, acetonitrile and methanol in the ratio (30:45:25 v/v/v), pH adjusted to 4.8 with ortophosphoric acid. The mobile phase was was filtered through a 0.45μ cellulose nitrate filter, sonicated for 15 min and delivered at a flow rate of 1ml/min. Detection was performed at a wave length of 241 nm at ambient temperature. Linearity was obtained in a concentration range of 30 to130 µg/ml with a correlation coefficient (r2) of 0.999. The limit of detection and limit of quantification were 1.08 and 3.24 μg/ml, respectively. No interference of excipients in determining tablet formulation; identical results were obtained like that of the standard sample.  The proposed RP-HPLC method is simple, accurate, precise, rapid and economical to be employed for routine analysis of carvedilol in pharmaceutical dosage forms.