The drugmaker released its so-called guidance fo 2009 and forecasts that earnings and revenue will wind up below Wall Street forecasts. A key reason for the declining profit are lower sales of its Vytorin and Zetia cholesterol pills, which are sold as part of a joint venture with Schering-Plough.

In a statement, Merck ceo Dick Clark blamed “a volatile global economy,” currency exchange rates and “continued challenges” for key products. The drugmaker is already in the process of eliminating 7,200 jobs and closing plants as generic competition to big-selling meds looms (back story), undermining a heralded turnaround (see Forbes).

As for specific products, revenues from the Gardasil HPV vaccine are expected to be flat next year, as Merck continues to struggle with questions over safety and cost. Sales were down 4 percent in the recent third quarter, for instance. Although, revenue from other vaccines will increase to between $2.8 billion and $3.1 billion, compared with an estimated $2.6 billion to $2.8 billion this year.

On the bright side, sales of the Januvia diabetes pill are expected to reach between $2.4 billion to $2.7 billion next year. Profits excluding one-time items will be $3.15 to $3.30 a share next year, compared with analyst estimates of $3.52. The declining US dollar will reduce earnings by 6 percent in 2009. However, Merck did not change its 2008 earnings forecast of $3.28 to $3.32 a share, and reaffirmed guidance for 2010.