Forest Labs ( FRX) was dealt somewhat of a setback Friday by the Food and Drug Administration, which is asking for additional dose-confirmation studies before it allows Forest to market lercanidipine, a hypertension drug, in the U.S. Forest says the studies will take two years to complete. The launch delay comes as a big surprise because lercanidipine is commercially available at this dose in 60 countries, with no known safety issues. Forest Labs licensed the drug from Italian drugmaker Recordati to sell in the U.S. Forest shares were off 13% to $93.37 in premarket trading Friday. Forest received an approvable letter from the FDA for lercanidipine in August, in which the agency requested additional information. The two sides met in December. Forest says it prepared an adequate response to FDA's questions, but it was unable to persuade the agency. Study results on lercanidipine were presented recently at a medical meeting in which the drug was shown to be as effective as Pfizer's ( PFE) hypertension drug Norvasc, and with fewer side effects.