ABSTRACT:
An accurate, sensitive, precise, rapid and isocratic RP-HPLC method for simultaneous estimation of Cilastatin, Imipenem and Relebactum in the bulk drug and in pharmaceutical metered dose inhalers is developed and validated. The best separation achieved on Hypersil BDS Reverse Phase-C18 column (250mm × 4.6 x 5-µm) with acetonitrile as the organic modifier and dipotassium hydrogen phosphate [0.03M] in water with pH 3.2 adjusted with ortho-phosphoric acid (0.1% v/v) as mobile phase at a flow rate of 1.0mL min-1. UV detection carried out at 265nm. Retention times observed at 3.107 min. for Imipenem, 3.885 min. for Cilastatin and 10.516 min for Relebactum. A linear response observed at concentration range of 20-120 mcg/ml for Cilastatin, 20-120mcg/ml for Imipenem and 10-60 mcg/ml for Relebactum respectively with average correlation coefficient of = 0.999. The percentage assay for Cilastatin, Imipenem and Relebactum were found 98.37, 99.72 and 99.18% respectively. The limit of detection (LOD) was found to be 0.01µg/mL for Cilastatin, 0.02µg/mL for Imipenem and 0.05µg/mL for Relebactum. The limit of Quantification found to be 0.03µg/mL, 0.06µg/mL and 0.15µg/mL for Cilastatin, Imipenem and Relebactum respectively. The excipients present in the formulation did not interfere with the assay procedure. The method is suitable for application in quality-control laboratories, because it is simple and rapid with good accuracy and precision.