Biotechnology company Cephalon Inc. said Monday that chairman and CEO Frank Baldino Jr. will not be resuming his duties at the company in 2010 and will remain on a medical leave of absence indefinitely.

In August, the Frazer-based company said Baldino, who also is the company's founder, took a medical leave, but did not provide additional details.

J. Kevin Buchi, the company's chief operating officer, will continue to perform Baldino's day-to-day responsibilities pending his return.

In October, the company reported record earnings and raised its 2010 guidance.

Cephalon's best-selling drug is Provigil, used to treat narcolepsy.

Shares were trading at $65.66, up 17 cents, shortly after trading opened this morning.