A better-than-expected first quarter and a continuing stock buyback program have given Forest Laboratories ( FRX) the confidence to raise its guidance for the fiscal year that ends next March. The New York-based drugmaker said Tuesday it was boosting its earnings forecast to a range of $2.42 to $2.50 a share from its prior estimate of $2.37 to $2.42. In early-afternoon trading, however, the stock was off 57 cents, or 1.3%, to $43.38 on higher-than-average trading volume. The announcement came during Forest's release of its first-quarter results, in which revenue of $816.3 million topped the $716.8 million for the same period last year. Forest earned $200.6 million, or 62 cents a share, vs. a profit of $216.6 million, or 62 cents a share, for the year-ago period. One-time items affected both periods. The just-completed quarter includes a $60 million licensing charge and an $8.8 million stock-option expense. The first quarter last year had a $36.4 million tax gain. The first quarter was paced by the antidepressant Lexapro, which produced sales of $507 million, or 62% of Forest's revenue. Last week, a federal court judge ruled in favor of Forest , agreeing that Teva Pharmaceutical Industries ( TEVA) had infringed on Lexapro's key patent. Forest's other big drug, Namenda, posted first-quarter sales of $151 million, up 32% from the year-ago period. Namenda is prescribed for moderate and severe Alzheimer's disease. Forest, which specializes in licensing drugs from other companies, offered an update for several products in the pipeline, including the blood-pressure drug nebivolol. Licensed from Mylan Laboratories ( MYL) in January, nebivolol is still undergoing some additional testing required by the Food and Drug Administraion.