* Sandoz files application for generic version of ADHD drug
* First generic challenge to Vyvanse
(Adds details, shares)
LONDON, May 19 (Reuters) - Pharmaceutical firm Shire (SHP.L) said it had received notice of an application by drugmaker Sandoz to launch a generic version of its top-selling hyperactivity drug Vyvanse.
Shire said on Thursday it had received a "Paragraph IV" notice from Sandoz, the generic arm of Swiss drugs company Novartis (NOVN.VX), regarding a filing of an application to the U.S. drugs regulator for a generic version of the ADHD medicine.
Shire has 45 days to decide if will challenge the application, which is the first for a generic version of Vyvanse.
It said Vyvanse was protected by 16 patents, all of which expire in 2023.
Shares in the company were 1.3 percent lower at 1,923 pence at 1450 GMT. (Reporting by Paul Sandle; Editing by Jon Loades-Carter)