A factorial study of combination hypertension treatment with metoprolol succinate extended release and felodipine extended release results of the Metoprolol Succinate-Felodipine Antihypertension Combination Trial (M-FACT).
BACKGROUND
Many hypertensive patients require combination therapy to achieve target blood pressure (BP). beta-Blockers and dihydropyridine calcium channel blockers are effective as monotherapy in hypertensive patients and have complementary mechanisms for lowering BP.


METHODS
This multicenter, randomized, placebo-controlled, unbalanced factorial study included a 4- to 5-week single-blind placebo, 9-week, double-blind treatment as well as a 2-week double-blind, down-titration period. Patients (N = 1092) were randomized to one of 16 treatment groups: extended-release (ER) metoprolol succinate (25, 100, or 400 mg), ER felodipine (2.5, 10, or 20 mg), ER felodipine/ER metoprolol succinate (2.5/25, 2.5/100, 2.5/400, 10/25, 10/100, 10/400, 20/25, 20/100, or 20/400 mg), or placebo.


RESULTS
At baseline, treatment groups were well balanced; mean sitting BP was 152.6/99.9 mm Hg. Monotherapy with ER metoprolol succinate induced dose-related reductions in sitting systolic/diastolic BP (DBP) (mean 8.1/7.7 to 9.7/11.1 mm Hg) as did ER felodipine (mean 7.7/7.7 to 14.0/11.8) and the combinations reflected additive effects (mean 13.8/11.0 to 19.8/15.2). The decline in the placebo group was 2.1/4.0 mm Hg. All combinations were more effective than their components (P < .05 for all but ER metoprolol succinate 25/ER felodipine 20). When compared with the highest doses of the individual agents (ER metoprolol succinate 400 mg; ER felodipine 20 mg), the low-dose combination ER metoprolol succinate 25/ER felodipine 2.5 was approximately as effective (differences in DBP <1 mm Hg). The most common adverse events leading to discontinuation were peripheral edema (4%), headache (2%), and fatigue (1%). Higher rates of peripheral edema and flushing were associated with high-dose ER felodipine, either alone or in combination.


CONCLUSIONS
The antihypertensive effects of ER metoprolol succinate and ER felodipine are dose-related, and when given in combination, their BP-lowering effects are additive over a wide dose range. Low-dose combination therapy is comparable in effectiveness to high-dose monotherapy but is better tolerated.
Department of Medicine and Pharmacology, New York Medical College, Valhalla, New York 10595, USA. joanne_pryor@nymc.edu
William H
WH
Frishman
James W
JW
Hainer
Jennifer
J
Sugg
D000284:Administration, Oral; D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000627:therapeutic use*; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D015736:Felodipine / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D008875:Middle Aged
D000319:Adrenergic beta-Antagonists; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D003692:Delayed-Action Preparations; D008790:Metoprolol; D015736:Felodipine