NOVEL SIMULTANEOUSSTABILITY-INDICATING ESTIMATION METHOD FOR DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE BYRP-HPLC: APPLICATIONTOAPIANDPHARMACEUTICAL DOSAGE FORMS

Objective: To develop a novel stability-indicating validated method for the simultaneous determination of dorzolamide hydrochloride (DH) and timolol maleate (TM) in API and pharmaceuticals. Methods: Reverse-phase chromatographic separation was achieved using a Spursil C18 column with a mixture of methanol and potassium dihydrogen phosphate buffer (7:3v/v) as the mobile phase at pH 3.5. The flow rate was maintained at1.0 ml/min. DH and TM were detected at 290 nm. The method was validated for linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and forced degradation studies. Results: The developed method achieved effective separation, with DH and TM eluting at retention times of 2.189 and 3.136 min for standards, and 2.299 min and 3.091 min for samples, respectively. The method showed excellent linearity across 20–100 µg/ml for DH (r² = 0.999) and 5–25 µg/ml for TM (r2 = 0.9993). The mean recovery percentages were 99.99% for DH and 98.79% for TM, with a percentage relative standard deviation (%RSD) below 2.0, confirming the accuracy and precision of the method. Low LOD and LOQ values indicated high sensitivity, while forced degradation studies confirmed the method's stability, indicating capability. Conclusion: The validated procedure is reliable, accurate, sensitive, and precise for the simultaneous qualitative analysis and stability assessment of DH and TM in both bulk drugs and commercial pharmaceutical formulations. This method is suitable for routine standard quality control applications.