The cyclooxygenase 2 (COX-2) inhibitor celecoxib can induce arrhythmic beating of heart cells, according to laboratory studies conducted at the State University of New York in Buffalo (Frolov RV et al. J Biol Chem. 2008;283:1518-1524).
The drug's effect is caused by a novel pathway unrelated to its COX-2
The researchers discovered that celecoxib inhibited certain potassium channels from Drosophila fruit flies, rats, and humans and led to pronounced heart arrhythmias in Drosophila and arrhythmic beating of rat heart cells in culture. Specifically, the drug inhibited the passage of potassium ions into and out of heart cells through what are known as delayed rectifier potassium channels. These effects occurred despite the absence of cyclooxygenases in Drosophila and in the face of an inhibitor of both COX-1 and COX-2 administered to rats.
Hampton T. Drug-Arrhythmia Link. JAMA. 2008;299(9):1008. doi:10.1001/jama.299.9.1008-d