Haribaskar*, T. Revathi, Ramesh Dhani
Department of Pharmaceutical Analysis, Ratnam Institute of Pharmacy, Pidathapolur, Nellore, Andhra Pradesh, India
A B S T R A C T
A new method was established for simultaneous estimation of Olmesertan medoxomol and Chlothalidone by RP-HPLC method. The chromatographic conditions were successfully developed for the separation of Olmesertan medoxomil and Chlorthalidone by using C18, 250 mm ˣ 4.6 mm 5µ (Inertsil ODS), flow rate was 1.0ml/min, mobile phase ratio was Acetonitrile and water (70:30), detection wave length was 238nm. The instrument used was Shimadzu HPLC Auto Sampler, Separation module 2695, PDA Detector 2998, Empower-software version-2. The average retention times for Olmesartan Medoxomil and Chlorthalidone was found to be 3.5 and 6.7 min, respectively. According to United States pharmacopeia, system suitability tests are an integral part of chromatographic method. They are used to verify the reproducibility of the chromatographic system. To ascertain its effectiveness, system suitability tests were carried out on freshly prepared stock solutions. The calibration was linear in concentration range of 50µg/ml – 150µg/ml and 50µg/ml – 150µg/ml, with correlation coefficient 0.9999 and 0.9999 for Olmesartan Medoxomil and Chlorthalidone, respectively. The low values of RSD indicate that the method was precise and accurate. The effect of degradation products on the main peaks of Olmesartan Medoxomil and Chlorthalidone was determined by treating samples with different stress conditions like acid stress, alkali stress, peroxide stress, thermal stress and photolytic stress. The peak purity was found to be well below the purity threshold. Finally, it can be concluded that the assay values of formulation were the same as mentioned in the label claim with RSD of < 1.0%. The proposed method was found to be accurate, precise, reproducible and stable, and can be successfully applied for routine analysis of both the drugs in combined tablet dosage forms.
Keywords: Olmesertan medoxomil, Chlorthalidone, HPLC