The pill is one of Merck's most important experimental products, and some analysts have predicted it could garner annual sales of $1 billion or more, if approved by the U.S. Food and Drug Administration.
NEW YORK (Reuters) - Merck & Co's <MRK.N> experimental obesity drug taranabant did not show impressive effectiveness in a late-stage trial and its side effects were worse than expected, an analyst at health-care investment bank Leerink Swann said on Monday.
The pill is one of Merck's most important experimental products, and some analysts have predicted it could garner annual sales of $1 billion or more, if approved by the U.S. Food and Drug Administration.
It belongs to the same family of medicines as rimonabant, a Sanofi-Aventis <SASY.PA> drug that was rejected by U.S. regulators after it was linked to suicidal thoughts and depression. Both drugs work by blocking cannabinoid receptors in the brain. They are the same receptors that make people hungry when smoking marijuana.
Leerink Swann analyst Aileen Salares based her unfavorable analysis of taranabant's trial results on an abstract, or abbreviated summary, of the two-year study. Full data from the two-year trial will be formally presented late this month at the annual meeting of the American College of Cardiology in Chicago.
!ADVERTISEMENT!Merck said it could not comment on the study until the data are formally presented, citing rules of the cardiology group.
The 2 milligram dose of the Merck drug -- the maximum dose expected to be used in any approved product -- failed to produce the desired 5 percent weight loss, compared to placebo, Salares said in a research report.
Although patients reported only a 4 percent weight loss, Salares said U.S. regulators might have flexibility to approve the medicine if it had a favorable safety profile.
"Safety was not nearly as clean as expected, though," she said, with almost twice as many patients taking the 2 milligram dose of taranabant dropping out of the trial because of psychiatric side effects than patients taking placebos.
The side effects included suicidal thoughts and neurological problems.
While the highest dose of the Merck drug used in the trial, 4 milligrams, did achieve the desired 5 percent weight loss, it was associated with a considerably higher incidence of psychiatric side effects, Salares said.
Shares of Merck were down 50 cents, or 1.2 percent, to $41.25, in morning trading on the New York Stock Exchange, amid a moderate downturn for the drug sector.
(Reporting by Ransdell Pierson)
