Primary objective:
To quantify the dose-related effects of various doses and types of calcium channel blockers on systolic and diastolic blood pressure versus placebo in patients with primary hypertension.

Secondary objectives:
1. To determine the effects of calcium channel blockers on variability of blood pressure.
2. To determine the effects of calcium channel blockers on pulse pressure.
3. To quantify the dose-related effects of calcium channel blockers on heart rate.
4. To quantify the effects of calcium channel blockers in different doses on withdrawals due to adverse events.