Ambien is an FDA-approved medication that can put an insomniac to sleep in a matter of minutes at night. But when taken during the day, the little pill can cause slurred speech, blurred cognition and erratic behavior.
Zolpidem, a generic version of the drug, has now been implicated in a car crash two weeks ago, when Kerry Kennedy, the daughter of Robert F. Kennedy, swerved into a tractor-trailer on New York's Route 684 and kept driving. Witnesses said she had been weaving in and out of lanes for miles before the accident.
Toxicology reports showed 14 nanograms per milliliter of zolpidem in Kennedy's blood, according to the Associated Press. Both her blood and urine samples were negative for alcohol or other drugs.
"Ambien is a very bizarre drug," said Paul L. Doering, co-director of the Drug Information and Pharmacy Resource Center at the University of Florida. "It is only supposed to be taken as directed and is not intended to be taken during the day unless you are a shift worker.
"There is the sedative effect itself," said Doering. "You can be groggy, with slurred speech and not all there. That's why they call them sleeping meds."
And, when taken during the daytime, there is also a high risk for abuse, he said.
Kennedy, 52, is the seventh of the 11 children of Robert F. Kennedy and the ex-wife of New York's Gov. Andrew Cuomo. She is a human rights activist and mother of three.
Police found Kennedy slumped in her white Lexus on the morning of July 13, according to Reuters. She was unsteady on her feet and slurring her words. Initially she told police she may have accidentally taken the sleeping aid earlier that day, mistaking it for her thyroid medication.
At a court appearance July 17, she pleaded not guilty to a charge of drunk driving and said the hospital where she was treated found no trace of drugs and doctors had suspected a brain seizure. She is due back in court Aug. 14.
In 2006, her cousin Patrick Kennedy, the former congressman from Rhode Island and the son of the late Sen. Edward Kennedy, was sent to alcohol and drug rehab, after crashing his car while on Ambien in Washington, D.C.
Ambien, or its generic cousin zolpidem, is a sedative-hypnotic that works by slowing activity in the brain, according to the National Institutes of Health. It is prescribed for those who have difficulty falling or staying asleep. It's meant to be taken immediately before bedtime and its effects last about seven to eight hours.
Sometimes patients can experience memory problems on awakening. Some have reportedly taken Ambien, left their bed and driven cars, prepared and eaten food, had sex or made phone calls while under the influence of the drug and not fully awake, according to theFood and Drug Administration.
The drug has a risk for anterior-grade amnesia, as well, according to Doering. "Memory never burns from RAM to ROM."
"The things that happen to a driver can be very scary," he said. "You are in a state where you are dreaming, but you are not quite sure whether you are awake or dreaming."
Drug Mix-Ups Are Common
Kennedy's statement that she may have mistakenly taken Ambien instead of her thyroid medicine is not far-fetched, according to experts.
New York City mother and writer Nancy Kruger Cohen wrote about the same mix-up in an article, "Mothers Little Helper," for the New York Times magazine in 2010. She said she begins each day with her gray thyroid tablet, but one day, while getting her two children ready for school, she grabbed the wrong prescription bottle.
"As the pill goes in, my tongue pauses -- Is it usually pink? -- but I swallow anyway. And then the mistake is clear," Cohen writes. "I have taken a sleeping pill at 8:15 a.m."
She describes a day of bedlam, one in which she texts her girlfriends, throws up over tea, crashes in bed and eventually spends the evening playing with her children, uncharacteristically oblivious to the mess and confusion. Her memory of the day is, of course, spotty.
Since 2000, the Food and Drug Administration (FDA) has received more than 95,000 reports of medication errors -- some of them doctor or pharmacy mistakes, but many by consumers themselves.
"Chaos at home is a common denominator in a lot of accidental poisonings," Marcel J. Casavant, a toxicologist and medical director of the Central Ohio Poison Center at Nationwide Children's Hospital in Columbus, told ABCNews.com at the time.
"Kids may be playing, mom is fixing dinner, dad is getting in from work and grabbing mail or whatever dads do," he said. "But there's a lot going on, and someone decides it's time to administer medication."
At least half of all Americans take at least one prescription drug, with one in six taking three or more medications. The biggest increases in prescriptions were for antidepressants, nonsteriodal anti-inflammatory drugs, and blood sugar and cholesterol lowering drugs, according to a 2004 Department of Health and Human Services report.
Casavant said his poison control center, one of three in Ohio, fields at least 100 calls a day, "a couple of dozen" of which are unintentional medication mix-ups. "We have a lot more chemicals and a lot more medicine these days."