Developing a highly validated and sensitive HPLC method for simultaneous estimation of losartan and spironolactone in tablets and human plasma

An isocratic HPLC method had been developed and validated for rapid simultaneous separation and determination of the two antihypertensive drugs, losartan and spironolactone in tablet dosage forms and also in presence of human plasma within 6 minutes. Separation was carried out on a Thermo Scientific ® BDS Hypersil C 8 column (5 µm, 2.50×4.60 mm) using a mobile phase of ACN: 0.025 M KH 2 PO 4 (60:40, v/v) adjusted to pH 3.49 with ortho - phosphoric acid at ambient temperature. The flow rate was 1 ml/min and maximum absorption was measured using DAD detector at 235 nm. The retention times of losartan and spironolactone were recorded to be 3.47, and 4.63 minutes respectively, indicating a shorter analysis time. Limits of detection were reported to be 0.07 and 0.15 µg/ml for losartan and spironolactone, respectively, showing a high degree of the method sensitivity. The method was then validated according to FDA guidelines for the determination of the drugs either in tablets with highly precise recoveries or clinically in human plasma specially regarding pharmacokinetic and bioequivalence studies.