AJ Allmendinger has been released by Penske Racing, the NASCAR outfit announced Wednesday.
Following the Californian's indefinite suspension from NASCAR after he tested positive for prohibited substances last month, the NASCAR organisation has decided to dismiss him with immediate effect.
Allmendinger landed at Penske Racing for the 2012 season following the departure of 2004 Cup champion Kurt Busch, whose relationship with the team became strained following a number of incidents both on and off the track.
The 30-year-old started the season with a victory in the 24 Hours of Daytona, driving for Michael Shank Racing, but his Cup results during the year have failed to match those of his team-mate Brad Keselowski, who has won three races thus far.
Allmendinger has joined the 'Road to Recovery' programme as he hopes to return behind the wheel in NASCAR, although it remains uncertain when he could be reinstated.
"Penske Racing fully supports NASCAR's substance abuse policy and we are disappointed with AJ's positive drug test results," said Roger Penske.
"AJ is a terrific driver, a good person and it is very unfortunate that we have to separate at this time. We have invested greatly in AJ and we were confident in his success with our team.
"The decision to dismiss him is consistent with how we would treat any other Penske Racing team member under similar circumstances. As AJ begins NASCAR's 'Road to Recovery' programme, we wish him the best and look forward to seeing him compete again in NASCAR."
According to a team statement, Sam Hornish Jr will continue to drive the #22 Penske Dodge in the Sprint Cup Series next weekend at Pocono and "for the foreseeable future" while it evaluates its options for the 2013 season.