Vioxx (generic name: rofecoxib) is a Cox-2 inhibitor drug (coxib) used to treat symptoms of arthritis. Manufacturer Merck & Co. has removed its blockbuster arthritis drug from the market worldwide because new data from a clinical trial found an increased risk of heart attack and stroke. Merck decided to remove the drug from the market after data from the trial showed an increased risk of heart attack, stroke, blood clots, and other cardiovascular complications.

The data comes from a three-year study aimed at showing that Vioxx at a 25-milligram dose prevents recurrence of polyps in the colon and rectum. The trial was stopped after Merck discovered the higher heart risk compared to patients taking dummy pills.

Before the withdrawal of Vioxx, the FDA announced that patients taking Vioxx have a 50 percent greater chance of heart attacks and sudden cardiac death. The study, presented at an epidemiologists' conference, also found patients taking the highest recommended daily dosage of Vioxx had three times the risk of heart attack and sudden cardiac death as those not taking standard painkillers.

In a study of more than 8,000 patients that compared rofecoxib (Vioxx) with traditional nonsteroidal anti-inflammatory drug (NSAID) naproxen, the risk of cardiovascular problems, including heart attack, chest pain related to heart disease, stroke, sudden death, and blood clots, was more than two times higher in the rofecoxib group than in the naproxen group.

Cox-2 inhibitors, like older drugs such as ibuprofen and naproxen, are nonsteroidal anti-inflammatory drugs (NSAIDs). Older NSAIDs reduce inflammation by blocking an enzyme called Cox-2, but they also block another enzyme called Cox-1. This enzyme helps protect the lining of the stomach, so blocking Cox-2 can cause stomach irritation. Cox-2 inhibitors only block Cox-2.