The simple, accurate and precise absorption ratio method has been developed for the simultaneous estimation of ritonavir and lopinavir in combined tablet dosage form. The lmax of ritonavir and lopinavir were found to be 239nm and 259nm respectively. For the estimation by Q-analysis method, the lmax those selected were 239nm and an isoabsorptive point for both the drugs as 257.4nm. The linearity range lies between 5-30mg/mL for ritonavir and 20-120 mg/mL for lopinavir at their respective wavelengths. Both the drugs were found in good agreement with the label claimed in the marketed formulation. Ritonavir and lopinavir in standard mixture were determined as 98.6% and 101.3% respectively. In the tablets both the drugs were estimated as 98.3% and 99.9%. Statistical validation of the data has been carried out and it reveals that the proposed method is sensitive and economical too for the routine analysis of the drugs in combined dosage form.
