Pfizer Inc. said Friday it is ending a safety study of its pain drug Celebrex because of difficulty finding patients. The trial was designed to measure the effects of Celebrex on patients who were taking the drug to treat juvenile idiopathic arthritis. Pfizer said it was having trouble enrolling patients in the trial, and the study was not likely to produce meaningful results because patients with the condition tend to use Celebrex for a short time and because the rate of side effects was very low. Sales of Celebrex grew 6 percent to $2.52 billion in 2011, which made it Pfizer's fifth-best-selling drug. It was originally approved in 1998, and Pfizer was required to do the safety study in 2006 after Celebrex was approved as a treatment for juvenile idiopathic arthritis.
