Mibefradil (Posicor) Drug for High Blood Pressure: Use, Side Effects, Interactions

Mibefradil
(Posicor, United States and Canada)

Use:

Mibefradil or Posicor is a calcium channel blocker useful in cardiovascular conditions like high blood pressure or hypertension, angina or heart pain, and congestive heart failure.

How It Works:

Like all calcium channel blockers, Mibefradil or Posicor dilates coronary and peripheral blood vessels. It does this by blocking the influx of calcium ions through "channels" in cardiovascular tissue. Because this influx of calcium is associated with vessel constriction, the constriction does not occur and the vessels are kept open.

Side Effects:

Mibefradil or Posicor can cause a slight decrease in heart rate. Other reported side effects include dizziness, fatigue, and light headedness. Some people may be bothered by stomach irritation, and swallowing the tablets whole may reduce this side effect.

Cautions for People:

Because Mibefradil or Posicor can affect the heart rate, people with heart beat problems may not be able to use it, or alternatively may have to be monitored closely.
Elderly people are at increased risk for side effects with Mibefradil or Posicor and may have to have their dosage reduced.

Drug Interactions:

Mibefradil or Posicor inhibits the some of the liver's ability to metabolise some other drugs - terfenadine, astemizole, cisapride, cyclosporine, tricyclic antidepressants. Thus the concentrations of these drugs would increase meaning side effects may be seen. A dose adjustment may be required.

Further Reading:

Am J Hypertension 1997;10:189
Clin Cardiology 1997;20:562
The Medical Letter 1997;39(1013):103

Added to Virtual Drugstore February 1998.

The relevant product monographs must be regarded as the appropriate sources of prescribing information.