Pfizer Inc. and Johnson & Johnson said Monday they are ending development of an intravenous formulation of a drug to treat Alzheimer’s disease after the treatment failed in two late-stage clinical trials.

The companies said bapineuzumab intravenous did not work better than placebo in two late-stage trials in patients who had mild to moderate Alzheimer’s disease.

The drug is designed to prevent the buildup of plaque in the brain. J&J said it is not discontinuing development of the compound and noted it has ongoing studies including a mid-stage neuroimaging study with bapineuzumab delivered subcutaneously.

Johnson & Johnson made a big bet on bapineuzumab in 2009, agreeing to invest up to $1.5 billion initially. The two companies said July 23 that the drug had failed in a different trial.

Johnson & Johnson, based in New Brunswick, New Jersey, said it will take a charge of $300 million to $400 million in the third quarter.

Dublin-based Elan Corp. PLC, which licensed the drug to Johnson & Johnson in 2009, said it will take a $117.3 million charge of its own.

U.S.-traded shares of Elan lost 10 percent, or $1.34, to $11.91 in after-hours trading. Shares of New York-based Pfizer lost 2.7 percent, or 66 cents, to $23.60. Johnson & Johnson stock edged down by 84 cents, or 1.2 percent, to $68.

Current treatments for Alzheimer’s can only temporarily ease symptoms of the disease, which include increasing memory loss, confusion, wandering and aggression.

In the latest trial, bapineuzumab was tested on about 1,300 patients who lacked a gene that is associated with a greater risk of Alzheimer’s. Last month the companies said the drug also didn’t work on patients who do have that gene. Pfizer and Johnson & Johnson were running two other late-stage trials as part of a very large testing program for the drug.

Worldwide, about 35 million people already have dementia, of which Alzheimer’s is the most common type. In the U.S., about 5 million have Alzheimer’s. Finding a drug that could at least slow the disease has become a sort of Holy Grail in the pharmaceutical industry. A successful medicine would be guaranteed to generate billions in annual sales, given the world’s aging population.