LOS ANGELES -- Jeff Conaway's manager says the former star of "Taxi" and 1978's "Grease" is in a coma following a drug overdose, possibly from pain pills.

Manager Phil Brock said the 60-year-old actor was found unconscious May 11. He is hospitalized in critical condition.

Brock said Conaway is in a coma in an Encino, Calif., hospital and his recovery is uncertain. The name of the hospital was not disclosed.

As part of the reality show "Celebrity Rehab" in 2008, Conaway discussed his addiction to drugs and alcohol.

His manager described Conaway as a "gentle soul" but one who has been unable to "exorcise his demons."

Conaway also appeared in the TV series "Babylon 5."