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Indication of Cox-2 inhibitor drugs like Celebrex in management of arthritis Pain

By Wasanyi David Pharm D Rph

Cyclo-oxygenase 2 (COX-2) inhibitors are drugs which were approved by the FDA for short term management of arthritis pain. COX-2 are effective in controlling pain associated with; osteoarthritis, rheumatoid arthritis, menstruation, and rhabdomyolisis. COX-2 inhibitors do not cure any of the above disease states; they block pain and reduce inflammation associated with the above disease states. Although reducing inflammation reduces the rate of disease progression, in general COX-2 do not cure any of the above disease states.

Cox-2 inhibitor drugs were approved by the FDA for short term use in management of mild to severe pain. But, many patients have been using them for a period longer than the recommended duration by both the manufacturer and the FDA that is greater than 6 months. Because of prolonged exposure to high doses of COX-2 inhibitor drugs, some patients had started experiencing adverse effects like gastro intestinal bleeding and cardio vascular diseases2. On addition to gastro intestinal bleeding and increased risk for heart diseases, valdecoxib (bextra) puts a patient at a risk of developing a serious skin rash at the beginning of therapy or any time during the course of therapy and Vioxx( rofecoxib) was documented to critically increase the risk of cardiovascular diseases3. That explains why those two drugs were removed from the market2.

Many experts are concerned about Celebrex that it might have other adverse effects on addition to what is already known, because it belongs to the same class as bextra and vioxx. The chances of celebex causing these problems when appropriately prescribed are very low. Many patients have been using it in appropriate doses and some are still using it but they have not yet developed any of the cardiovascular diseases. Studies conducted by the oncology clinic of North America, used high doses of celebrex (400mg twice a day, recommended maximum dose 200mg a day) for a period longer than it recommended period by the manufacturer. Celebrex did not pose any other threat apart from significant increase in the risk of cardiovascular disease which is common with all drugs in its class. Which means that if celebrex is taken as recommended by it manufactures it is as good as any other NSAID on the market2.

On April 7 2005, the FDA released a statement informing the public that the benefits of using celebrex out weighs the risks when used in properly selected patients. That means that not all patients qualify to use celebrex to manage pain. Physicians have to evaluate the risks the patients have before putting them on celebrex Patients at a high risk of cardiovascular diseases should not use it at all3.

The FDA went ahead and advised Pfizer the manufacturers of Celebrex, to reverse the label of celebrex to include on it the warnings put on labels of None Steroidal Anti-inflammatory drug like naproxen. This means that the superiority of the Cox-2 over the Non Steroidal Anti-inflammatory drugs was neutralized, and that both patient, and the health care providers should use celebrex with the knowledge of its adverse effects in mind3. The FDA advised practitioners to use the lowest effective dose for the shortest duration consistent with individual patient treatment goals, include a Medication Guide as part of the labeling. And this information should be given to the Patient at the time the drug is dispensed to inform patients of the potential for Cardiovascular and Gastrointestinal risk associated with, Non Steroidal Ant-inflammatory Drug in general, and Celebrex in specific. The Medication Guide should also inform patients on the need to discuss with their doctor the risks and benefits of using Non Steroidal Ant-inflammatory Drug and the importance of using the lowest effective dose for the shortest duration possible3.

To ensure that any other risk associated with celebrex is communicated to the patients, the FDA advised Pfizer to do more studies in the patients using celebrex to make sure that any other safety related issues are dealt with in an appropriate way3. Although there is a concern on using COX-2 inhibitors in management of arthritis related pain. The new guideline put forward by the FDA on the use of the Cox-2 inhibitors recommended the patients to continue using them, but careful evaluation of the patient’s risk factors before the patient is started on them. Celebrex the Cox-2 drug still available on the United States drug market can be used to treat moderate to severe pain associated with osteoarthritis and rheumatoid arthritis, but patients and physicians should be made aware that cox-2 are only approved for short term use and that they don’t offer any added advantage on protection against gastro intestine bleeding.

Reference

1. Bombardeir C M.D. An evidence based evaluation of gastrointestinal safety of Coxibs. Am J Cardio. March 2002;89:6.

2.Anonymous. Pfizer statement on new information regarding cardiovascular safety of celebrex. http://www.pfizer.com/are/investors_release/2004

3. The FDA. COX-2 Selective (includes Bextra, Celebrex, and Vioxx) and Non-Selective Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) www.fda.gov/cder/drug/advisory/COX2.htm. Released on April 07 2005. Accessed on June 27, 2005