Drug maker AstraZeneca PLC (AZN.LN) Wednesday said it intends to start phase IIb studies of AZD3480 in attention deficit hyperactivity disorder, or ADHD.

The company said it has agreed to make a $10 million milestone payment to Targacept Inc. (TRGT).

AstraZeneca said it plans to continue development of AZD1446 for Alzheimer's disease, which is currently in phase one and was discovered in the ongoing AstraZeneca-Targacept research collaboration.

In Alzheimer's disease, development of AZD1446 has been prioritized over further development of AZD3480, AstraZeneca said.

Company Web site: www.astrazeneca.com

-By Jason Douglas, Dow Jones Newswires; 44-20-7842-9272; jason.douglas@dowjones.com