Instant and sustained-release verapamil in the treatment of essential hypertension.

ABSTRACT

In a series of controlled studies for periods of 4 to 6 weeks comprising 103 patients altogether, and in 1 long-term trial for 1 year, various dosages of instant and sustained-release verapamil were administered in the treatment of mild and moderate essential hypertension. One of these trials was a double-blind comparison with nifedipine, in which the 2 calcium antagonists had an equally good effect on blood pressure. A significant blood pressure reduction was achieved with verapamil both at rest and during isometric work in most patients. About 10% of the patients were nonresponders. Pharmacokinetic studies demonstrated great interindividual variations in plasma concentrations of verapamil and its active metabolite norverapamil. Except for 1 study, no significant correlation was found between drug concentration and blood pressure reduction. All formulations of verapamil were well tolerated by the patients, and adverse effects were generally mild and often transient. No negative metabolic effects were observed during long-term treatment; serum lipids, in particular, were unaffected. PQ intervals on the electrocardiogram were significantly but moderately prolonged. QRS and QT intervals were unchanged. No increase in body weight occurred. It is concluded that verapamil is an efficacious, safe drug and a first-line treatment alternative in mild and moderate essential hypertension. The recently developed sustained formulation of the drug renders a simple dosage regimen possible.