Please note: I am not a doctor and this is a topic that requires a great deal of knowledge and expertise, which can best be provided by your doctor. If you are using a Calcium-Channel Blocker, it is important to continue using the medication as directed by your doctor until you and your doctor have reviewed your personal situation and your doctor has advised you to use something else. Do not stop using your medication based on anything you read here or in the newspaper. Talk to your doctor. YET MORE CONTROVERSY ABOUT CALCIUM-CHANNEL DRUGS For nearly 20 years, calcium-channel blocker medications have been popular drugs prescribed to address high blood pressure and other problems. Over the last several years, increasing controversy has arisen about the benefits and risks associated with the use of these types of drugs. Commonly used calcium-channel blockers include: Adalat, Calan, Cardene, Cardizem, Dilacor, DynaCirc, Isoptin, Nimotop, Novasc, Plendil, Procardia, Vascor, and Verelan. ==MARCH 1995 Three years ago, at the March 10, 1995 meeting of the Epidemiology and Prevention Council of the American Heart Association (AHA), researchers from the Cardiovascular Health Research Unit of the University of Washington raised concern that the use of calcium- channel blockers to treat hypertension (high blood pressure) might appear to increase the risk of heart attack in otherwise healthy people. Their concern added to the concerns raised by other researchers that the use of calcium-channel blockers might increase the risk of heart attack in people who have already had a heart attack. (see Psaty B et al. Circulation. 1995; 91:925). To put this in perspective, the researchers noted that the increased risk to the individual using these medications, if there is increased risk, would appear to be small: for patients taking diuretics or beta-blockers, the incidence of myocardial infarction is about 10 in 1,000 patients a year; for patients using calcium- channel blockers, the incidence increases to 16 in 1000 patients a year. Nonetheless, the researchers did encourage physicians to follow the national guidelines which recommend diuretics and beta- blockers for first-line treatement of hypertension (as then published in Archives of Internal Medicine, 1993;153:154-183). ===JANUARY 1996 I posted the following message: Jan. 26, 1996 research update: Continuing Controversy Over Calcium-Channel Blockers People using the short-acting form of nifedipine, a calcium channel blocker, marketed in the US as Procardia (by Pfizer) and as Adalat (by Bayer) should consult their doctors about whether they might want to shift to another type of medication. Calcium channel blockers have often been prescribed for people with high blood pressure and angina. About 6 million Americans are taking the long-acting form of this medication, which has been under continued scrutiny since controversial studies were published last year. Over 2 million prescriptions for the short-acting form of nifedipine were written in the US in 1994. While the controversy continues, the American College of Cardiologists and other experts strongly caution people reading these reports NOT to discontinue using these drugs without first talking to their doctors. The Controversial Studies Last March, a study was presented at the American Heart Assn. meeting that suggested that hypertensive patients taking short-acting calcium channel blockers had a 60% higher rate of heart attack than those using diuretics and beta blockers. (In patients using this type of drug, 16 out of every 100,000 per year might have a heart attack; in patients using diuretics and beta blockers, only 10 out of every 100,000 per year might have a heart attack.) This report was later published in the August '95 Journal of the American Medical Assn. and was mentioned here on the forum at that time. In response to this report, the National Heart, Lung and Blood Institute soon issued a warning about conflicting reports on the safety of short- acting calcium channel blockers. At about the same time, a study was published in Circulation which reviewed earlier studies (a "meta-analysis study") and pooled their findings to develop new statistical analyses of the studies. This study of 16 clinical trials indicated that high doses of nifedipine increased the death rate by almost 300%. (Patients using high amounts of short-acting nifedipine had an average death rate of 6 out of every 100 patients, compared to a death rate of 2 or 3 out of every 100 patients who were not using the medication.) This week, a study based on European data was reported to have found no evidence to suggest that these medications are dangerous. What Experts Are Saying The manufacturers of these drugs have found flaws in these studies and data, as have others. The FDA advisory committee studying this issue announced its recommendation this week that doctors should be discouraged from prescribing short-acting forms of nifedipine and that a warning label should be placed on this form of the drug, but did not find sufficient data to suggest a warning label be required on all types calcium channel blockers. Government experts recommend that the short-acting nifedipine should be used "with great caution, if at all." If You Are Using This Type of Medication Remember, the total risk numbers are still quite low, the FDA is not even 100% convinced that these drugs are very dangerous, and the studies are still quite controversial among experts. Check with your doctor about whether there might now be a more appropriate alternative to using this type of medication. Follow the advise of expert cardiologists and do not discontinue taking the medication on your own. Consult your doctor before making any changes or discontinuing any medications, including this one. === NOVEMBER 1996 In November, 1996, another group of researchers presented their study to an American Heart Association meeting suggesting that calcium-channel blockers are safe and do not present increased risk of heart attack or death from their use; moreover, the health benefits of these drugs were reported to be considerable. ===JANUARY 1998 The New England Journal of Medicine carried an article entitled "Conflict of Interest in the Debate Over Calcium-Channel Antagonists." The authors reported that their study of articles examining the controversy about the safety of calcium-channel blockers published between March 95 - Sept. 96 revealed that "Authors who supported the use of calcium-channel antagonists were significantly more likely than neutral or critical authors to have financial relationships with manufacturers of calcium-channel antagonists (96% vs 60% vs 37%, respectively). Supportive authors were also more likely than neutral or critical authors to have financial relationships with any pharmaceutical manufacturer, irrespective of the product (100%, vs 67% vs 43%, repectively)." They summarized their study with the conclusion that "Our results demonstrate a strong association between the authors' published positions on the safety of calcium-channel antagonists and their financial relationships with pharmaceutical manufacturers." In their discussion, they noted that they did not believe that any authors or researchers were influenced by their financial relationships with pharmaceutical companies, but that the appearance of these relationships could affect public confidence. ===MARCH 1998 The New England Journal of Medicine published an article on a study of the possible effects of calcium-channel blockers in patients who have both hypertension and diabetes. The article reports on the interim results of the Appropriate Blood Pressure Control in Diabetes (ABCD) Trial. The goals of the study were to observe the effects of blood pressure control on kidney function and to compare the effects of ACE inhibitors vs calcium-channel blockers. After 5 years of followup, the study was halted for diabetic patients with hypertension who were using calcium-channel blockers "because of a marked difference in the number of myocardial infarctions" (25 heart attacks in the patients using the calcium-channel blockers vs 5 heart attacks in the patients using ACE inhibitors). There are many potential factors that could make the results of the study of questionable value, however, and the editorial cautions that clear conclusions about the risks vs benefits of these medications and treatment for diabetics with high blood pressure await the results of more studies, including the nearly 3 dozen studies now underway. The editorial writer, James Cutler, M.D. of the National Heart, Lung, and Blood Institute, states that "In the interim, if guidance is needed on the selection of anti-hypertensive drug regimens, physicians should consult the newest guidelines in the 'Sixth Report of the Joint National Committe on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure'. With few exceptions, these guidelines reiterate the recommendation that a diuretic, a beta-blocker, or both should be chosen for the initial drug treatment of hypertension." (see Arch Int Med, 1997; 152:2143-46). == Making decisions about which medications to use for any individual patient requires good information about the medication and the patient. If you are not certain that you understand the risks vs benefits of any medication you are using, you should be sure to talk with your doctor. If you are using a calcium-channel blocker medication, it is possible that this is the best choice for you. It is also possible that there may be other drugs that could be a wiser choice for you. As always, talk to your doctor and make sure you understand your options.