1. Nifedipine, a slow-channel calcium blocker, causes smooth muscle relaxation and thereby results in falls in peripheral vascular resistance and systemic arterial pressure.
2. In an uncontrolled open study nifedipine was given sublingually to 10 patients with blood pressures of 180/120 mmHg or above.
3. After a single dose of 10 mg, all patients showed a significant reduction in blood pressure within 10 min. The maximum effect was seen at around 1 h and blood pressure was reduced for up to 6 h or more.
4. Two patients with chronic renal failure and one with phaeochromocytoma also showed a similar antihypertensive response.