Pfizer Inc. and Johnson & Johnson say they are ending development of a once-promising drug designed to trea Alzheimer's disease after the treatment failed in two late-stage clinical trials.

The companies say their drug bapineuzumab did not improve cognition or mental function in patients with mild to moderate Alzheimer's disease when compared to placebo. It was hoped that bapineuzumab would reduce the decline in physical and mental function for patients with Alzheimer's. Current treatments can only temporarily ease symptoms of the disease.

The two companies said July 23 that the drug had failed in a different trial. All other studies are being discontinued, and Johnson & Johnson said it will take a charge of $300 million to $400 million in the third quarter.

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