Tiazac (diltiazem HCl) has been approved for the treatment of chronic stable angina. Tiazac was previously approved for the treatment of hypertension. Tiazac, a once-daily calcium channel blocker, has been proven highly effective in important angina efficacy parameters; it significantly reduces both angina attack rates and nitroglycerin consumption. Tiazac's central effects and peripheral vasodilating action balances oxygen supply and demand producing significantly greater increases in total duration of exercise compared to placebo. Additionally Tiazac effectively reduces blood pressure of hypertensive patients over the 24-hour dosing interval with a side-effect profile comparable to placebo, even when dosed up to 360 mg.