The Therapeutic Goods Administration (TGA) in Australia has updated warnings on a popular sleeping drug.
The sleeping drug Stilnox, also called Stildem or Zolpidem, will in future be sold in packs of no greater than 14 tablets - down from 21.
The updated warning comes as a result of numerous reports of strange and potentially dangerous side-effects which include changes in behaviour and mental state, sleep walking, and undertaking strange and potentially dangerous behaviours while apparently asleep.
The TGA says Stilnox packs will include significantly changed Consumer Medicine Information (CMI) information about the side effects of Zolpidem which now include the less common adverse effects of rage reactions, worsened insomnia, confusion, agitation, hallucinations and other forms of unwanted behaviour.
Sleep walking, driving motor vehicles and other unusual and on some occasions dangerous behaviours whilst apparently asleep have been reported along with preparing and eating food, making phone calls and having sexual intercourse.
The TGA says people experiencing these effects have had no memory of the events and significantly such side effects can occur at therapeutic doses, without any intake of alcohol.
The TGA says alcohol intake heightens the risk of such side effects and warns the reactions could occur among both first-time and regular users, at prescribed doses and without the consumption of alcohol.
Australians wanting to report adverse reactions to the drug should phone 1300 134 237.
Zolpidem is sold in Australia under the brand-names Dormizol, Zolpibell, Zolpixdem, Somidem and Stildem.
It is also sold in the United States and in March this year the Food and Drug Administration (FDA) requested that all manufacturers of sedative-hypnotic drug products, such as Stilnox update their product labeling to include stronger language concerning potential risks.
These risks listed by the FDA include severe allergic reactions and complex sleep-related behaviours, including sleep-driving.
Also included were warnings about anaphylaxis (severe allergic reaction) and angioedema (severe facial swelling), which can occur as early as the first time the product is taken and complex sleep-related behaviours which may include making phone calls, and preparing and eating food (while asleep).
Experts say patients being treated with sleep medications should read the information before taking the product and talk to their doctors if they have questions or concerns.
The FDA has recommended that the drug manufacturers conduct clinical studies to investigate the frequency with which sleep-driving and other complex behaviours occur in association with individual drug products.