Merck & Co Inc said on Tuesday it expects first-quarter earnings per share to be between 95 and 98 cents, excluding items, below the average estimate on Wall Street of $1.01.

Including items, the drugmaker sees earnings per share between 52 cents and 60 cents.

With the euro exchange rate at about $1.31 in the first quarter, currency is expected to have a 1 to 2 percent unfavorable impact on sales in the first quarter.

The company reiterated its 2012 full-year forecast, calling for earnings per share between $3.75 and $3.85, excluding restructuring- and acquisition-related costs, and between $2.04 to $2.30 per share including those items.

Merck said it expects revenue at or near 2011 levels on a constant currency basis. But at current exchange rates, 2012 sales would be reduced by about 2 to 3 percent.

(Reporting By Debra Sherman; Editing by Gerald E. McCormick)