Blood pressure lowering efficacy of calcium-channel blockers as second-line therapy for primary hypertension

Primary objective: To quantify the additional reduction in systolic blood pressure (SBP) and diastolic blood pressure (DBP) of calcium-channel blocker (CCB) therapy as a second-line drug in hypertensive patients.

Secondary objectives:
1. To determine the effects of second-line CCB on variability of blood pressure.
2. To determine the effects of second-line CCB on pulse pressure.
3. To quantify the effect of second-line CCB on heart rate.
4. To quantify the effect of second-line CCB on withdrawals due to adverse effects.

This is a protocol.