A clinical study of cardiac patients who suffered an allergic reaction to the widely-prescribed drug clopidogrel, also known by the pharmaceutical name Plavix, found that treatment with a combination of steroids and antihistamines can alleviate the allergic reaction symptoms thereby allowing patients to remain on the drug, say doctors from Thomas Jefferson University Hospital. The study followed 24 patients, who developed Plavix allergies after undergoing coronary stent procedures.
Eighty-eight percent (21 of 24) were able to stay on Plavix uninterrupted after being treated with the antihistamines and a short course of steroids. Primary Investigator Michael P. Savage, M.D., director, Cardiac Catheterization Laboratory at Thomas Jefferson University Hospital and Kimberly L. Campbell, M.D., cardiology fellow and lead author, presented their findings at the American College of Cardiology's Annual Scientific Session on March 30 2009.
"This is a very important study for many cardiac patients but especially those with stents," said Savage. "Every patient who receives a stent must take Plavix to help prevent stent thrombosis which is clotting of the stent. This obviously poses major problems if the patient suffers an allergic reaction to the medication. To discontinue taking the drug can lead to a heart attack which may be fatal. Those with a drug eluting stent are required to be on the drug for at least one year. Our patients with drug eluting stents actually averaged 17 months on Plavix versus the minimum of one year. That's a very long time to not be on a medication that may save your life."
Plavix is one of the most prescribed drugs world-wide. Data from 2007 shows Plavix is the fourth most sold drug in the United States with almost four billion dollars in sales, according to IMS Health, a leading pharmaceutical industry monitoring company. It is estimated that about six percent of those taking the drug showed some signs of an allergic reaction.
John R. Cohn, M.D., chief of Adult Allergy at Thomas Jefferson University and Hospitals and a key contributor to the study noted, "Previously, when patients had an allergic reaction to Plavix we would give an alternative drug but they can have their own side effects. Rather than giving the secondary drug we concentrated on suppressing the patient's allergic symptoms they were having to Plavix by administering low doses of steroids and antihistamines while continuing the drug. What we found was that most of our patients became tolerant to Plavix, essentially becoming 'desensitized' to the drug enabling them to continue treatment. Once this occurred we were able to discontinue the steroids and even the antihistamines."
Previous anecdotal studies showed some evidence that patients could be desensitized to Plavix, but this is the first systematic study to demonstrate allergy to the drug could be managed without stopping the drug after a reaction was found.
"The saying goes 'necessity is the mother of invention' and that's exactly what we have here," said Campbell. "Plavix is a necessity in treating many cardiac patients, especially those with stents. Patients with allergic reactions have few alternatives and stopping Plavix can result in life-threatening complications. We needed to find a way to keep Plavix-allergic cardiac patients on this drug to help ensure positive cardiovascular outcomes and in this small group we did. Hopefully, in the future, we can expand the study and investigate ways to apply this in treating allergic reactions to other life-saving drugs."
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