New data from Australian and United Kingdom (UK) health agencies sheds light on bizarre behaviors associated with a commonly prescribed sleep medication, Ambien. One report from Australia’s Federal Health Department describes 104 cases of hallucinations and 62 cases of amnesia experienced by people taking Ambien or Ambien CR, also known by its generic name, zolpidem. The Australian health department report also mentioned 16 cases of strange sleepwalking by people taking the medication.
In one of these sleepwalking cases a patient woke with a paintbrush in her hand after painting the front door to her house. Another case involved a woman who gained 23 kilograms over seven months while taking zolpidem. “It was only when she was discovered in front of an open refrigerator while asleep that the problem was resolved,” according to the report.
Zolpidem, sold under the brand names Ambien, Ambien CR, Stilnoct and Stilnox, is widely prescribed to treat insomnia and other disorders such as sleep apnea. While doctors say that Ambien can offer much-needed relief for people with sleep disorders, they caution that these newly reported cases should prompt a closer look at its possible side effects.
The UK’s Medicines and Healthcare products Regulatory Agency, meanwhile, has recorded 68 cases of adverse reactions to zolpidem from 2001 to 2005.
The newly reported cases in the UK and Australia add to a growing list of bizarre sleepwalking episodes linked to the drug in other countries, including reports of people sleep-driving while on the medication. In one case, a transatlantic flight had to be diverted after a passenger caused havoc after taking Ambien.
There is no direct causal relationship that has been proven to connect Ambien with these behaviors. The drug is a benzodiazepine-like hypnotic that promotes deep sleep by interacting with brain receptors for a chemical called gamma-aminobutyric acid. While parts of the brain become less active during deep sleep, the body can still move, making sleepwalking a possibility.
The product information for prescribers advises that psychiatric adverse effects, including hallucinations, sleepwalking and nightmares, are more likely in the elderly, and treatment should be stopped if they occur.
Millions of people have taken the drug without experiencing any strange side effects. Unlike older types of sleep medications, Ambien does not carry as great a risk of addiction.
The US Food and Drug Administration says it is continuing to “actively investigate” and collect information about cases linking zolpidem to unusual side effects.
The Ambien label currently lists strange behaviour as a “special concern” for people taking the drug. “It’s a possible rare adverse event,” says Sanofi-Aventis spokesperson Melissa Feltmann, adding that the strange sleepwalking behaviours “may not necessarily be caused by the drug” but instead result from an underlying disorder. She says that “the safety profile [of zolpidem] is well established”. The drug received approval in the US in 1993.