Heather Locklear mugshot, September 28, 2008

Santa Barbara prosecutors have charged former Melrose Place star Heather Locklear with misdemeanor driving under the influence, following her arrest on Sept. 27.

Locklear's "obvious impairment" stemmed from prescription drugs, police told The Associated Press. Toxicology tests turned up no alcohol or illegal narcotics.

"She had prescription medication in her system that could have impaired her ability to safely drive a motor vehicle," Santa Barbara Deputy District Attorney Lee Carter told New York's Daily News.

A California Highway Patrol officer noticed Locklear's car parked on a highway and blocking a lane of traffic in Montecito, a town near Santa Barbara where Oprah Winfrey and other celebrities have homes.

In June, Locklear sought treatment for anxiety and depression. The actress is due in court on Jan. 26. She could face a minimum fine of $1,600 dollars and up to six months in jail if convicted. Locklear's attorney had no comment.