Promising Alzheimer's Drug Falls Flat in Clinical Trials

During early testing, the drug Dimebon showed great promise for halting cognitive decline associated with Alzheimer's disease - but in clinical trials, the drug failed.

The drug, developed by Medivation and Pfizer, showed virtually no effect after six months, according to an article in the New York Times. Dimebon showed no difference in treating cognitive decline or behavioral problems associated with Alzheimer's when compared with a placebo.

The results were especially disappointing because in previous testing, Dimebon had performed better than any drug already approved to treat Alzheimer's disease. Results seemed to indicate that it improved cognitive function or staved off mental decline for about 18 months. Current treatments can only stave off decline for about six months.

In the wake of the testing results, shares of Medivation lost two thirds of their value, dropping to $13.10. Shares of Pfizer fell 28 cents, about 1.6 percent, to $17.32.