prothena corp shares reversed course tuesday dropping 10 to 3011 after the company said the food and drug administration granted fast track designation for prx012 a potential bestinclass antiamyloid beta antibody therapy currently being investigated in a phase 1 clinical study for the treatment of alzheimers disease the stock had traded as much as 5 higher earlier in the session the fdas fast track designation program is designed to expedite the development and review of drugs intended to treat a serious condition such as alzheimers with evidence demonstrating the potential to address an unmet medical need a drug candidate that receives fast track designation may be eligible for more frequent interactions with the fda to discuss the drug candidates development plan and if relevant criteria are met eligibility for accelerated approval and priority review