LONDON - AstraZeneca PLC said Tuesday it has stopped development of its drug motavizumab for preventing serious respiratory syncytial virus disease but would continue working on other applications.

The London-based pharmaceutical company, which has operations near Wilmington, said it would take a write-down of $445 million on fourth-quarter accounts but said this would not change its forecast for earnings.

AstraZeneca shares were down 18 cents to $45.77 shortly after trading opened on the New York Stock Exchange.

AstraZeneca has sought approval for motavizumab to prevent a type of lung infection caused by respiratory syncytial virus, the leading cause of infant hospitalization in the United States.

The company had been reviewing its options for motavizumab after U.S. regulators expressed concern about the rate of side effects associated with the drug and asked for more clinical data in August.

Respiratory syncytial virus causes more than 125,000 infant hospitalizations each year, and up to 500 deaths, according to studies cited by AstraZeneca.