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T98-33 Print Media: 301-827-6242
June 8, 1998
Consumer Inquiries: 800-532-4440
In many cases, drug interactions can be addressed by appropriate labeling changes and public education, but due to the complexity of the prescribing information needed in this case, and seriousness of side effects, FDA and Roche agreed that it would be difficult to administer Posicor safely. The following may be used to respond to inquiries.
Posicor is a calcium-channel blocker, chemically unlike the other approved products in this class. Posicor was approved in June of last year, to be used in the treatment of patients with hypertension and chronic stable angina.
Posicor reduces the activity of certain liver enzymes that are important in helping the body eliminate many other drugs. Inhibiting these enzymes can cause some of these other drugs to accumulate in the body to dangerous levels.
When Posicor entered the market in August of 1997, its enzyme-inhibiting properties were described in the labeling. The labeling specifically listed three drugs (astemizole, cisapride, and terfenadine) that could be expected to accumulate to dangerous levels if Posicor was coadministered.
In December, after learning of several cases in which patients suffered serious adverse reactions after taking Posicor with one or more of the other drugs, FDA strengthened the labeling of Posicor, and two more drugs (lovastatin and simvastatin) were added to the label's list of those that should never be coadministered with Posicor. FDA also issued a public warning about this problem and the company issued a Dear Doctor letter to physicians.
From spontaneous reports and ongoing trials, FDA and Roche have continued to learn of adverse reactions related to coadministration of Posicor with several other drugs. At present, more than 25 drugs are known to be potentially dangerous if used with Posicor -- a number and diversity of drugs that cannot be practically addressed by standard label warnings.
Since Posicor has not been shown to offer special benefits (such as treating patients who do not respond to other antihypertensive and anti-anginal drugs), the drug's problems are viewed as an unreasonable risk to consumers.
Patients now taking Posicor should not simply discontinue treatment because stopping medications can be risky. Instead, patients should promptly consult with their physicians about appropriate alternative therapy. In addition, patients now taking Posicor should not add any new medication to their current treatment without consulting their physicians.
Roche Laboratories is providing information in a "Dear Doctor" letter to physicians, pharmacists, nurse practitioners, and other health care professionals. Questions about the withdrawal of Posicor can be addressed to Roche's 24-hour hotline at 1-800-205-4611.
The following is a list of drugs that depend on the same liver enzyme as Posicor (mibefradil). Use of them in combination with Posicor could be dangerous.
| Generic name | Trade Name |
| amiodarone | Cordarone |
| astemizole | Hismanal |
| bepridil | Vesture |
| cisapride | Propulsid |
| cyclosporine | Neoral, Sandimmune |
| cyclophosphamide | Cytoxan |
| desipramine | Norpramin |
| erythromycin | Erythrocin, Ilosone, others |
| etoposide | VePesid |
| flecainide | Tambocor |
| flutamide | Eulexin |
| halofantrine | Halfan |
| ifosfamide | Ifex |
| imipramine | Tofranil |
| lovastatin | Mevacor |
| mexiletine | Mexitil |
| pimozide | Orap |
| propafenone | Rythmol |
| quinidine | Cardioquin, Quinaglute, Quinidex, others |
| simvastatin | Zocor |
| tacrolimus | Prograf |
| tamoxifen | tamoxifen |
| terfenadine | Seldane |
| thioridazine | Mellaril |
| vinblastine | Velban |
| vincristine | Oncovin |
For more information about this withdrawal of Posicor, see: