Posikor

Mibefradil, the active ingredient of Pozikor, is a T-type calcium channel blocker . Blocking T-type calcium channels slows the heartbeat and thus reduces blood pressure and helps treat angina pectoris . Unlike other calcium channel blockers , mibefradil prefers type T channels to type L channels , from which it was concluded that mibefradil has a greater affinity for type T channels than other drugs with a similar principle of action. The explanation why blocking T-type channels slows the heartbeat is as follows. The action potential of the pacemaker cells begins with a gradual increase, as T-type channels and other cationic channels open. When the electric potential reaches a certain level (-30 mV), other channels open, which leads to a rapid flow of cations into the cells and, therefore, a sharp jump in potential. When type T channels are blocked, the initial increase in potential is slower, since only part of the channels continues to work. Consequently, the level of membrane potential at which other cationic channels open is reached more slowly than without exposure to the drug. Due to this, the time spent on one heart beat increases. ^[one]

• Dizziness
• Weakness
• Swelling of the legs
• Arrhythmia
• Very slow heartbeat
• AV block II degree

After numerous complaints about side effects, the drug was withdrawn from the market. As it was found out, Pozikor is incompatible with drugs that are processed in the liver by the same enzymes as mibefradil. This is due to the fact that mibefradil - the active substance of the drug - inhibits these enzymes , which is why other drugs accumulate in concentrations hazardous to health ^[1] . Cases of necrosis of the abdominal muscles and damage to the kidneys have been reported. ^[one]

Also, cases of a too strong decrease in the heart rate after taking the drug (less than 45 beats / min.) Were recorded, and in some cases the drug caused severe arrhythmia . According to various sources, the number of deaths caused by this medicine varies from 24 to hundreds. The company itself recognizes only two or three of them.

The fact that mibefradil affects the activity of liver enzymes was known before the release of the drug on sale. A test was performed that showed that the medicine should not be used with three other drugs. Tests have also been carried out, showing that the drug can cause acute arrhythmia. The U.S. Food and Drug Administration had a choice: whether to allow the sale of the drug, or wait one year, and it was decided to release the medicine without a detailed study of possible side effects. At the time of release, it was written on the drug’s label that it should not be used with three other drugs. Subsequently, after numerous reports of incompatibilities, several more drugs were added to the list. At the time the medicine was taken from the market, there were 25 drugs on this list, among which were commonly used antibiotics , cancer drugs, and antihistamines . It was decided that such a risk is not justified, since the drug does not have significant advantages over other drugs for hypertension and angina pectoris .

• Calcium antagonists
• Heart pacemaker

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• Scriabine, A. (1999). Discovery and Development of Major Drug Currency in Use. In R. Landau (Ed.), Pharmaceutical Innovation: Revolutionizing Human Health (pp. 148-271). London, England: OtherWorld Books.
• Statement of Larry D. Sasich, Pharm. D, MPH And Sidney M. Wolfe, MD of Public Citizen's Health Research Group on the Withdrawal of the Calcium Channel Blocker Mibefradil (Posicor) From the Market. (2001). Public Citizen, 1.2.
• Hoffmann-La Roche Ltd. (1997). Pharmaceuticals: Two new products successfully launched. Roche - Corporate Media News, 1.2.