METHOD DEVELOPMENT AND VALIDATION FOR THE ESTIMATION OF RITONAVIR AND NIRMATRELVIR IN PHARMACEUTICAL DOSAGE FORM BY UV-SPECTROSCOPY

The present study describes the development and validation of a simple, economical, accurate, and precise UV spectrophotometric method for the simultaneous estimation of Ritonavir and Nirmatrelvir in active pharmaceutical ingredients and tablet dosage forms, in accordance with ICH guidelines. Ritonavir, an HIV protease inhibitor, and Nirmatrelvir, a SARS-CoV-2 protease inhibitor, were selected for their combined therapeutic significance in COVID-19 antiviral therapy. Solubility profiling revealed that Ritonavir was freely soluble in acetonitrile and methanol, while Nirmatrelvir was soluble in methanol. Considering cost and solubility, acetonitrile and methanol were used as solvents for Ritonavir and Nirmatrelvir, respectively. The λmax values were found to be 239 nm for Ritonavir and 228 nm for Nirmatrelvir. Linearity was established in the ranges of 20–80 μg/mL for Ritonavir and 2–18 μg/mL for Nirmatrelvir, with excellent correlation coefficients (r² = 0.999 and 0.9998, respectively). The method was validated for accuracy, precision, and sensitivity. LOD and LOQ were 0.01285 μg/mL and 0.03894 μg/mL for Ritonavir, and 0.13419 μg/mL and 0.40662 μg/mL for Nirmatrelvir. Recovery studies confirmed accuracy within 98.06–102.56%, and %RSD values were within acceptable limits (<2%), indicating good precision. The assay of marketed tablets showed drug contents of 99.39% for Ritonavir and 99.41% for Nirmatrelvir. Thus, the proposed UV spectrophotometric method is reliable, cost-effective, and suitable for routine quality control analysis of both drugs in bulk and tablet forms.