CLASS Study and COX-2 Drug Side Effects
This page describes the CLASS study and the side effects provided by COX-2 pain reliever drugs, focusing on the drug Celebrex. A number of studies have been conducted to evaluate COX-2 pain relievers.
In the late 1990s, CLASS (Celecoxib Long-term Arthritis Safety Study) engaged 8059 patients to evaluate gastrointestinal events and other adverse effects in those taking drugs similar to Vioxx: celecoxib (Celebrex) vs. ibuprofen (Advil), a traditional, non-selective pain reliever*.
The CLASS study found that those taking Celebrex were as likely to have cardiovascular side effects as patients taking a traditional pain reliever, such as ibuprofen. In other words, this study found no increase in side effects related to heart attack or stroke due to taking Celebrex, a COX-2 drug. The study also indicated that COX-2 inhibitors reduced pain, ulcers and other stomach problems caused by the traditional, ibuprofen type of pain relievers. The study report contained no indication of whether other COX-2 inhibitors, such as Vioxx, could cause any potentially harmful cardiovascular side effects.
However, not all COX-2 inhibitors are the same. Apparently, celecoxib is a much weaker drug, when compared to other COX-2 inhibitors. Physiology studies indicate that Vioxx is about 9 times more potent than Celebrex in terms of blocking of the COX-2 enzymes. (Find out more aboutCOX enzymes and COX-2 inhibitors.)
Celecoxib is a COX-2 inhibitor drug marketed by Pfizer in the United States under the trade name of Celebrex. Recent government- and manufacturer-led studies, unveiled in late 2004, found that both Celebrex and Bextra, another COX-2 inhibitor, may also induce myocardial infarction and cardiovascular side effects. The reported side effects are under intense investigation, but neither Celebrex nor Bextra have been recalled from the market. Pfizer plans to continue marketing the drug to doctors, but has stopped consumer advertising for the pain reliever.
*Traditional pain relievers inhibit both COX-2 and COX-1 enzymes, which act to protect stomach lining.