Felodipine vs hydralazine: a controlled trial as third line therapy in hypertension. Cooperative Study Group.

In a placebo-controlled, double-blind, randomized, parallel group study one hundred and one patients with supine diastolic blood pressure greater than or equal to 100 mm Hg phase V, despite treatment with atenolol 100 mg plus chlorthalidone 25 mg once daily also received either felodipine 5-20 mg twice daily or hydralazine 25-100 mg twice daily for 6 weeks. Felodipine achieved a lower supine blood pressure (mean +/- s.d. 177/108 +/- 29/8-138/82 +/- 19/8 mm Hg) than hydralazine (174/109 +/- 25/8-149/92 +/- 26/11 mm Hg), (P less than 0.05/P less than 0.001). Felodipine also lowered supine diastolic blood pressure to less than 90 mm Hg more often than hydralazine (42 vs 22 patients, P less than 0.001). The incidence of unwanted effects was similar in both groups. The felodipine treated patients experienced more ankle swelling and flushing than those in the hydralazine group who experienced more headache and minor gastro-intestinal upset.