What Is Mibefradil?

Mibefradil was a medication that was once approved for the treatment of angina and hypertension. The drug is no longer available due to evidence of serious drug interactions. Global healthcare company, Swiss-based F. Hoffmann–La Roche Ltd., manufactured and marketed the drug under the brand name Posicor.

The mibefradil medication is classified as a calcium channel blocker. This means that it goes through membrane channels in the body specifically designed for calcium—more specifically, the calcium T- and L-channels—and slows the movement of this chemical element. This reduces the amount of calcium in the blood vessels, which helps in relaxing them and supplying the heart with more oxygen-rich blood.

This process greatly helps in warding off angina pectoris, which is chest pain that occurs when the heart is not getting enough oxygen. Angina traces its roots to the Greek word anknone, which means strangling, and pectoris is related to the Latin word for chest, pectus. Angina is considered a prelude to myocardial infarction, or heart attack. Therefore, with more oxygen supplied to the heart's muscles, the organ's workload is greatly reduced.

People also used mibefradil to treat hypertension, which is characterized by high blood pressure. Like angina, hypertension is one of the risk factors of heart attack. The medication, however, was used to control high blood pressure, not cure it.

During its production run, Roche typically made and sold mibefradil in 50- or 100-milligram tablets. The drug was meant for oral administration, with a recommended dosage of 50 mg once a day. The most common side effects of mibefradil included abdominal pain, dizziness, headache, fatigue, nasal congestion, nausea and swelling of the legs. More serious signs, which were rarer, included breathing difficulties, fainting spells, skin rashes and slowed heartbeat.

On August 1997, the United States Food & Drug Administration (FDA) approved mibefradil. It placed it in its mid-range pregnancy category C of its classification system for level of harm pharmaceuticals pose to pregnancies. Animal studies, which involved administering 39 mm of mibefradil, showed that the drug was associated with a host of defects such as prolonged pregnancies, difficult childbirth, stillbirths and skeletal abnormalities. Despite the aforementioned risks, the FDA pointed to the benefits of the drug as an overriding factor in some cases. Roche, however, voluntarily withdrew mibefradil from the pharmaceutical market on 8 June 1998, citing potentially dangerous drug interactions with 25 medications.