Controlled release oral dosage formulations containing calcium channel blockers, and methods of use thereof, are provided for the once-a-day treatment of cardiovascular disorders, such as hypertension, angina, and cardiac arrhythmia. The active agent is preferably a dihydropyridine calcium channel blocker, such as nisoldipine. The formulation provides an increase in the bioavailability of the calcium channel blocker as compared to the bioavailability of the calcium channel blocker in other drug delivery formulations known in the art. In one embodiment, the formulation provides an increase in the bioavailability of the calcium channel blocker, nisoldipine, as compared to the same dose of nisoldipine in the coat-core version of the drug (SULAR.RTM.). The formulation can be in the form of a trilayer tablet containing a core or central layer and one or more barrier layers.