Levi Johnston

Sherry Johnston, the mother of Bristol Palin's ex-boyfriend, Levi Johnston, has pleaded guilty to drug possession.

Johnston, whose son is the father of former Gov. Sarah Palin's grandchild, pleaded guilty Wednesday in state Superior Court to one count of possession with intent to deliver the prescription painkiller OxyContin, according to the Anchorage Daily News.

Watch Levi Johnston talk about Palin's fame

The plea deal calls for Johnston, 43, to be sentenced to five years in prison, with two years suspended. Rex Butler, her attorney, said the deal also includes three years of probation after prison.

Butler said the Wasilla resident will be jailed at Hiland Mountain Correctional Center in Eagle River, Alaska, while awaiting sentencing, which is scheduled for November. Butler hopes to convince the state to let Johnston serve her sentence under house arrest via ankle monitoring.

Johnston was arrested in December with six felony drug counts involving a prescription painkiller.

Levi most recently appeared on the red carpet with comedienne Kathy Griffin at the 2009 Teen Choice awards.