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| |  Warning Labelling Changes For New Heart Drug Posicor WASHINGTON, MD -- December 22, 1997 -- The United States Food and Drug Administration is advising doctors about new warnings in the labelling of the drug Posicor (mibefradil), a treatment for hypertension and chronic angina. The new warnings provide additional information about two risks associated with the drug: extremely low heart rates and, when Posicor is taken with certain cholesterol-lowering drugs, a risk of muscle injury that can be life-threatening. The new warning regarding low heart rates advises physicians against prescribing Posicor to patients at high risk of developing dangerously low heart rates. Such patients, especially older people, include those whose heart rates are already relatively low and those taking another drug that slows heart rate. Posicor's risk of inducing excessively slow heart rates is similar to that of several other commonly-used drugs and was described in the labelling when the drug was first approved in June l997. The new, strengthened warning was developed after the FDA and the drug’s manufacturer, Roche Laboratories, received reports of dangerously lowered heart rates in about 20 patients who had taken Posicor. Many of the patients described in the reports had relatively low heart rates before starting Posicor, or had certain types of pre-existing heart disease that put them at high risk of such low rates. More than half of them were also taking another heart-rate-lowering drug, usually a beta-blocker. No deaths have been reported, but many patients became weak and light-headed. The second new warning states that Posicor should not be given to patients who are also receiving lovastatin or simvastatin. These drugs used to lower cholesterol are known as statins. In addition, pending availability of further information, co-administration of Posicor with atorvastin or cerivastatin is strongly discouraged. Two of the statins, fluvastatin and pravastatin, are not significantly metabolised in the same way as the other drugs. Mibefradil therefore would not be expected to have significant effects on fluvastatin or pravastatin blood levels or to increase the risk of muscle injury. The new label also warns against the simultaneous use of Posicor, any statin, and either of the immunosuppressants tacrolimus or cyclosporine. This new warning was added after the agency received seven reports of drug-associated muscle injury Drug-induced muscle injury is a known rare side effect of all of the statin cholesterol-lowering drugs including atorvastatin, cervistatin, fluvastatin, lovastatin, pravastatin and simvastatin, and it seems to increase in frequency with increasing dose. Patients with drug-induced muscle injury usually experience non-specific muscular symptoms (weakness, tenderness, and pain), but the most important consequences of injury are not muscular. The breakdown products of muscle can cause temporary or permanent damage to kidneys; and in severe cases, the heart can also be affected. Either of these complications can lead to death. Although Posicor does not itself cause muscle injury, administration of Posicor interferes with the body's metabolism of lovastatin and simvastatin and may interfere with the metabolism of atorvastatin and cerivastatin. The observed incidence of muscle injury with co-administration of Posicor and simvastatin appears to be much higher than the incidence seen during treatment with simvastatin alone. The immunosuppressants tacrolimus and cyclosporine interfere with the elimination of all of the statins and Posicor increases blood levels of cyclosporine and tacrolimus, so the three-way combination of Posicor, a statin, tacrolimus, or cyclosporine should also be avoided. More information on: Posicor
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