The pharmaceutical company Merck last week initiated a voluntary immediate worldwide withdrawal of its bestselling arthritis drug rofecoxib (Vioxx), because new research shows that it almost doubles the risk of myocardial infarction and stroke if taken for 18 months or more.

Rofecoxib, a cyclo-oxygenase-2 selective inhibitor, has been on the market since 1999 and is used by 2 million people in over 80 countries worldwide with 400 000 taking it in the United Kingdom. It is indicated for osteoarthritis and rheumatoid arthritis, and higher dose strengths are indicated for short term relief of acute pain (VioxxAcute).

The new study, …