Drugs in the same category as Merck & Co. Inc.’s withdrawn Vioxx painkiller will get close scrutiny to see if they also can cause heart attacks, U.S. regulators said on Thursday.
Vioxx is a COX-2 inhibitor, part of a family of drugs that were heralded as safer options to older medicines such as aspirin that can cause dangerous stomach bleeding. Some had even dubbed them “super-aspirin.”The only COX-2 drug proven to reduce stomach risks was Vioxx, but links to heart attacks and strokes in a study of patients who took the drug for three years prompted Merck to withdraw it on Thursday.”We are going to be more interested in looking at long-term data on new products that come down the pike,” Dr. Steven Galson, acting director of the Food and Drug Administration’s Center for Drug Evaluation and Research, told reporters on a conference call.Merck is seeking FDA permission to market another COX-2 inhibitor called Arcoxia, and Novartis AG wants to sell its COX-2 inhibitor called Prexige.”I’m sure that we are going to ask for more data, but I can’t tell you exactly what that data is,” Galson said.Galson said he was referring to COX-2 drugs awaiting approval, as well as ones already on the market, which would include Pfizer Inc.’s Celebrex and Bextra.The FDA in April 2002 had ordered Merck to change Vioxx’s label to warn about the possibility of heart attacks.A study earlier this year caused more worry about Vioxx’s potential for harm. FDA officials said they had been reviewing that data when Merck presented new findings this week and told the agency on Tuesday that it would pull Vioxx.”This is not a total surprise,” Galson said.Consumer group Public Citizen said FDA reviewers in the past raised concerns about possible cardiac problems with Celebrex and Bextra. Pfizer said both drugs were safe. FDA officials said they do not know why Vioxx raised the risk of serious cardiovascular problems.Vioxx, Celebrex and older drugs such as aspirin and ibuprofen are part of a group called nonsteroidal anti-inflammatory drugs, or NSAIDs.All NSAIDs increase blood pressure and cause fluid retention, but it is unclear if those effects caused Vioxx users to have heart attacks and strokes, Galson said.COX-2 inhibitors were made to reduce pain and inflammation in arthritis suffers and others who take the drugs long term.Aspirin and the older NSAIDs affect an enzyme called cyclooxygenase (COX). Researchers discovered there were two forms, known as COX-1 and COX-2, with COX-2 involved in pain and inflammation.By blocking COX-1, older NSAIDS “thin” the blood, which is why they protect the heart, but this mechanism can cause stomach damage. Scientists thought blocking only COX-2 would protect the stomach.Dr. Steven Nissen, a Cleveland Clinic cardiologist who has studied COX-2 inhibitors, said he thought the heart risk was limited to Vioxx. “Celebrex has been out there a long time, and these types of problems have not arisen,” Nissen said.Dr. Byron Cryer, a gastroenterologist at the University of Texas Southwestern Medical Center, said some experts believe the COX-2 inhibitors may affect the epithelium, the cells lining blood vessels, making blood more likely to clot.Patients should not panic and start taking over-the-counter NSAIDs, said Cryer, a spokesman for the American Gastroenterological Association.Patients taking Vioxx should talk to their doctors about alternatives, the FDA said. (Source: Reuters, Oct 2004)