Treatment of Hypertensive Urgencies and Emergencies with Nitrendipine, Nifedipine, and Clonidine

Nitrendipine is a new calcium antagonist of the 1,4-dihydropyridine group with strong vasodilating properties. In a randomized trial involving 45 patients, whose mean blood pressure was 236 +/- 24/129 +/- 21 mm Hg, 5 mg nitrendipine (given sublingually via a phiole) was compared with 20 mg nifedipine (given sublingually via two pierced 10-mg capsules) and 0.15 mg clonidine (given intravenously). Blood pressure and heart rate were assessed for 8 h after intake of the antihypertensive agents. Within 60 min, nitrendipine reduced blood pressure by an average of 78 +/- 17 mm Hg for the systolic and 42 +/- 12 mm Hg for the diastolic. Heart rate fell significantly from 106 +/- 17 to 87 +/- 11 beats/min. Nifedipine produced equivalent falls in systolic (-72 +/- 15 mm Hg) and diastolic (-41 +/- 11 mm Hg) blood pressure, but increased heart rate from 89 +/- 13 to 103 +/- 14 beats/min within 1 h. Intravenous administration of clonidine lowers systolic (-84 +/- 13 mm Hg) and diastolic (-35 +/- 10 mm Hg) blood pressure within 60 min. Heart rate decreased from 96 +/- 15 to 84 +/- 9 beats/min. The antihypertensive effect of each drug was maintained until 8 h after medication. Main side effects were observed in the nifedipine group (flush and reflex tachycardia) and in the clonidine group (dry mouth and drowsiness). In conclusion, nitrendipine, nifedipine, and clonidine show similar efficacy in the treatment of hypertensive urgencies and emergencies. However, sublingual application of the calcium antagonists is simple and safe; moreover, nitrendipine is better tolerated than nifedipine and clonidine.