Introduction: Free radical oxidative stress has been implicated in the pathology of a wide variety of clinical disorders. Antioxidants are agents which scavenge the free radicals and prevent the damage caused by them. Angiotensin II receptor blockers used in the treatment of hypertension, have also been reported to protect organs such as kidney and heart. Althoug, the mechanisms of these protective effects are not fully understood, it is generally thought that their antioxidant effects likely play a role. Amlodipine, a calcium channel blocker, seems to exert atheroprotective effects through its antioxidant properties related to its chemical structure and independent of its calcium channel-blocking effect. Though research has proved that olmesartan and amlodipine exhibit antioxidant activity independent of their antihypertensive effects, there are not many in vitro studies to analyse which drug is a better antioxidant. Objective: This in vitro study was done to compare the antioxidant activity of olmesartan and amlodipine. Materials and Methods: In this study, we demonstrated the antioxidant activities of 10 mg/ml stock solutions of olmesartan and amlodipine in vitro. DPPH (1,1 Diphenyl 2-picryl hydrazide) and Nitric oxide free radical scavenging assays were done. Results: Olmesartan showed significant (49.48%) and consistent free radical scavenging activity by DPPH and Nitric oxide radical scavenging assays. Free radical scavenging activity of amlodipine was more significant (56.89%) than olmesartan but was inconsistent and non-concentration dependent. Conclusion: Hence this in vitro study has proved that olmesartan has better antioxidant activity than amlodipine.
