2.1  Effects of antihypertensive drugs on oxidative stress
Table 2 lists the antioxidant drugs shown to reduce blood pressure in humans and animal models of hypertension253–328. These antioxidants have different mechanisms of action and various combinations may have synergistic effects on the regulation of blood pressure. For example, the antihypertensive effect of the combination of zinc sulfate, ascorbic acid, α-tocopherol, and β-carotene may be due to an increase in the bioavailability of NO324. By contrast, antioxidant drugs such as vitamin E, under certain conditions, can also increase the blood pressure in mice325. Vitamin E at doses greater than 150 IU daily increases the risk of all-cause mortality in humans326. The combination of vitamin C and polyphenols has also been reported to increase blood pressure variability229, and the antioxidant properties observed in vitro may not be observed in vivo328. The effect of chemicals on ROS production and blood pressure is complex and not easily predictable.