An in vitro study of the peroxyl and hydroxyl radical scavenging capacity of the calcium antagonist amlodipine.

Amlodipine has been reported to improve endothelial function in patients with arterial hypertension and to significantly limit the progression of carotid atherosclerosis. The aim of this study was to assess the total antioxidant activity of amlodipine. We measured the in vitro antioxidant activity of amlodipine as its ability to antagonize the oxidation of alpha-keto-gamma-methiolbutyric acid by both hydroxyl and peroxyl radicals. The results are expressed as Total Oxyradical Scavenging Capacity (TOSC) units. Reduced glutathione, uric acid and trolox were used as the reference antioxidants. Amlodipine showed an efficiency as scavenger of peroxyl radicals (TOSC: 5945 +/- 544 units/mg) significantly higher (>50%, P <0.001) than that of GSH (2733 +/- 636 units/mg), and 70% lower (P < 0.0001) than the value obtained with uric acid (18144 +/- 696 units/mg) and trolox (17522 +/- 734 units/mg). Of interest, the scavenging capacity of amlodipine towards hydroxyl radicals (1455 +/- 154 units/mg) was 320% higher (P < 0.00001) than that of GSH (358 +/- 112 units/mg), 20% higher than that of uric acid (1198 +/- 121 units/mg), and 100% higher than that of trolox (759 +/- 143 units/mg). Amlodipine has intrinsic antioxidant activity with both anti-hydroxyl and anti-peroxyl radicals activity.