The two popular painkillers Vioxx and Celebrex, heavily marketed as "super-aspirin," were prescribed for millions of patients who did not need them or should not have taken them, researchers said on Friday.
Merck & Co. Inc's Vioxx was recalled in September because a study linked the drug to increased risk of heart attacks and strokes, while Pfizer's Celebrex is under a cloud after data showing a similar heightened risk.
The study by doctors at Stanford University and the University of Chicago found the two COX-2 inhibitors were taken by millions of people who were not at risk of gastrointestinal bleeding, the main reason patients were told to switch from aspirin and other lower-cost painkillers.
COX-2 inhibitors cost 10 to 15 times as much as the drugs they replaced, the study published in the Archives of Internal Medicine said.
"We found a rapid, nationwide shift away from older, inexpensive drugs with better established safety and efficacy to newer, costly drugs with no real history," said study author G. Caleb Alexander, a medical ethicist at the University of Chicago.
Merck spent $161 million in 2000 on direct-to-consumer marketing of Vioxx, it said.
Using data from the National Center for Health Statistics, the study concluded that 73 percent of patients considered at low or very low risk of gastrointestinal problems should not have been considered for the newer drugs.
Gastrointestinal bleeding usually affects only at-risk patients who must take aspirin and other non-steroidal anti-inflammatory drugs, or NSAIDs, for long periods, it said.
"The findings demonstrate the challenge of limiting innovative therapies to the settings in which they are initially targeted and maximally cost-effective," Alexander wrote.