* EU healthcare watchdog starts review of Tredaptive
* Follows medicine's failure in a U.S. clinical trial
By Chris Wickham
LONDON, Dec 21 (Reuters) - Europe's medicines watchdog has launched a review of Merck & Co Inc's cholesterol drug Tredaptive after the medicine failed a U.S. trial assessing its effectiveness and safety.
Although the commercial fallout from any decision to pull the drug from the market in Europe would be limited, it would be a blow to Merck's reputation.
Bernstein analyst Tim Anderson estimates Tredaptive sales in Europe and other non-U.S. markets are running at only around $50 million a year, compared with Merck's overall revenue of $47 billion.
The drug is designed to raise "good" HDL cholesterol but the 25,000 patient U.S. study found it didn't do better at preventing heart attacks, deaths or strokes than traditional statin drugs that lower "bad" LDL cholesterol.
The large-scale trial also found that patients taking the drug suffered more non-fatal but serious side effects than those only taking statins.
The medicine was approved for use in Europe in 2008, but U.S. regulators were unwilling to approve it until Merck conducted the costly long-term study to better assess its safety and effectiveness.
Launching the review, the European Medicines Agency on Friday defended its decision to approve the drug, saying it was based on a full assessment of the evidence available at the time, including results from trials involving several thousand patients, which showed the benefits outweighed the risks.
"A risk management programme was established at the time to follow up on various issues concerning the use of the product," the agency told Reuters. "This included a requirement for the company to submit the results of a large, long-term study, the HPS2-THRIVE Study, which are now being made available."
Merck said on Thursday it no longer planned to seek regulatory approval for the drug in the United States and recommended doctors did not start new patients on Tredaptive in countries where it is already available.
The regulator backed that advice on Friday, but added patients currently using the drug should speak to a doctor at their next appointment and not stop their treatment.
Tredaptive is sold under the brand name Pelzont in Italy and Trevaclyn in both Italy and Portugal. A decision on the future of the drug in Europe is expected in January.