Merck & Co.'s third-quarter profit plunged 35 percent because of competition from generic drugs, lower sales of its top-selling medicine, and restructuring and acquisition charges.
It still beat Wall Street's profit expectations, but sharply lowered its own forecast for the full year,.
Generic competition continues to hammer asthma and allergy pill Singulair, cutting sales 53 percent to $280 million. The drug brought in $5.5 billion a year until its patent expired in August 2012 and cheap copycat versions flooded the market.
The world's third-biggest drugmaker by revenue previously has weathered generic competition to its blockbusters well, usually managing to keep total sales about the same level as before big patent expirations.
Revenue in the quarter totaled $11.03 billion, down 4 percent.
Besides Singulair, Merck is being hurt by generic versions of a half-dozen other drugs, plus unfavorable currency exchange rates, and its newer medicines aren't picking up all the slack.