Pfizer and Medivation, Inc. have entered into an agreement to develop and commercialize Dimebon, Medivation’s investigational drug for treatment of Alzheimer’s disease and Huntington’s disease. Dimebon currently is being studied in a confirmatory Phase III trial in patients with mild-to-moderate Alzheimer’s disease.     Under the terms of the agreement, Medivation will receive an upfront cash payment of $225 million and is eligible to receive as much as $500 million based on development and r...