Back in 2004, Merck had to pull their blockbuster COX-2 inhibitor Vioxx off the shelves. The drug was linked to an increase in heart disease and stroke, and the same doubt has surrounded Pfizer’s COX-2 inhibitor Celebrex (celecoxib) ever since. So, Pfizer conducted a Phase IV study comparing incidence rates of those adverse events compared to ibuprofen and naproxen. Twelve years, a patent expiration, and 24,000 patients later, Pfizer found that celecoxib was at least as safe as ibuprofen and naproxen, if not more so. That’s great news for arthritis sufferers at risk for heart disease and stroke, but Pfizer’s probably a little irritated they ran a massive study to disprove a rumor which likely bit into their Celebrex profits when they had market exclusivity.