Skip to Content

Ambien at High Doses Is a Driving Hazard

A small study of motorists on high doses of Ambien (zolpidem) has made headlines for highlighting the risks of driving with high blood-levels of the drug caused by overdosing or taking Ambien and not resting afterward.

The trial, led by toxicologist Laura Liddicoat, supervisor of the toxicology section of the Wisconsin State Laboratory of Hygiene in Madison, was presented at the American Academy of Forensic Sciences meeting on February 23 and by MedPage Today on March 9, 2006.

Liddicoat reported on a study of six patients and discussed how drivers with high blood levels of Ambien crashed their cars and had no memory of doing so. Apparently, the study subjects either took Ambien at high doses, or took it and did not subsequently "sleep it off" before getting behind the wheel - often intending to drive home and then sleep.

"They haven't slept it out and the drug was still in their system," Liddicoat reportedly said.

Ambien is reportedly taken by millions of Americans each year, and its effects are known well enough to lead a New York Times journalist to use the term "Ambien driver" as a descriptive.

According to Liddicoat, a standard 10-mg dose of Ambien produces average serum levels of 121 ng/mL (range: 58 ng/mL to 272 ng/mL). However, after eight hours of sleep, blood levels would return to zero, or close to it.

Study Results

The six study participants had blood levels of Ambien of up to 1,000 ng/mL - and in one case 4,400 ng/mL. One of these participants had an out-of-date Ambien prescription and bought her drugs online. Some participants combined Ambien with other depressants, but none of these six also ingested alcohol.

Other drivers with high blood levels of Ambien drove on the wrong side of the road, crashed into stationary objects and suffered confusion, loss of balance and memory loss, according to the report. They reported not knowing why they were in the hospital -or why they were being arrested.

Liddicoat reported that the study participants showed high deficits in psychomotor performance and cognitive abilities when driving within five hours after taking Ambien.

"Drugged driving cases have been steadily increasing over the last five years, and Ambien cases have mirrored this trend, reaching a peak of 45 cases a year in Wisconsin alone in 2003 and 2004."

According to MedPage Today, Liddicoat said in an interview that she is happy to help inform physicians, as the problems are related to how and when people take Ambien. She adds that she believes these people are not faking their confusion or memory loss, as questions like, "Why am I in the hospital?" are consistent among the patients.

Of note, Liddicoat also reports that no significant residual effects on memory or driving ability have been reported when people have been tested the morning after taking one dose of 10 mg (5 mg in the elderly) just before sleeping.

According to other medical records, many other drivers driving under the influence of high doses of Ambien had also been drinking, despite a warning by Ambien's manufacturer, Sanofi Aventis, against staking Ambien with alcohol. Sanofi's drug-label also instructs people to take Ambien just before going to bed, and to get a full eight hours' sleep, as well as cautioning against operating heavy machinery or driving.

Sanofi Aventis commented that "the drug's record after 13 years of use in this country shows it is safe when taken as directed," according to MedPage Today. The company also added it has provided the US Good and Drugs Administration with reports of people driving while sleep-walking, according to the New York Times.

Liddicoat presented these examples of impaired drivers, according to MedPage Today:

  • Driver taking 670 ng/mL while driving, reported to be "very out of it."
  • Driver taking 500 ng/mL plus Celexa (citalopram) crashed into a parked car, bizarre behavior, couldn't follow simple instructions.
  • Driver taking 820 ng/nL, poor comprehension, nearly fell over.
  • Driver taking 190 ng/mL plus other antidepressants driving southbound in northbound lane.
  • Driver taking 1,000 ng/mL plus Zoloft (sertraline) crashed into a truck; got drug online and continued to increase doses.
  • Finally, driver taking 4,400 ng/mL drove on rim of flat tire, hit mailboxes, very confused.

Posted: March 2006