People who take opioid-based drugs to treat chronic pain can drive about as well as others on the road, according to researchers from Rush University in Chicago.

The New York Times reported Dec. 4 that researchers used a driving simulator to compare the reaction times, weaving and accident rates of subjects taking oral morphine for pain to a control group that was not taking pain medication.

Lead researcher Asokumar Buvanendran said that, unlike occasional users, long-term pain patients develop tolerance to opiates that tends to limit their intoxicating effects. "If I suddenly took 30 milligrams of morphine, I'd probably sleep for 10 hours, whereas someone who took it for the last two years is probably as alert as I am now," he said.

Opiate-based medications including warning labels advising against operating heavy machinery, but Buvanendran suggested that restrictions on the activities of regular opioid users be reviewed. "There's no point in giving opioids to these patients if they can't return to functionality in society," he said.

Buvanendran presented his findings at the October annual meeting of the American Society of Anesthesiologists.