One of Britain's most popular sleeping drugs has been blamed for a series of bizarre events in which patients have driven their cars or had eating binges in the middle of the night while still unconscious.
New evidence has linked zolpidem to a series of incidents of strange and often risky behaviour, including a woman who painted her front door while still asleep and another user who put on just under four stone in seven months after she began raiding her fridge.
The research, by Australia's Federal Health Department, found 16 cases of odd sleepwalking, 104 of hallucinations and 62 of amnesia among users of the powerful sedative.
Britain's official medicines watchdog, the Medicines and Healthcare products Regulatory Agency (MHRA), said this weekend that it had recorded 68 incidents of adverse reactions to zolpidem between 2001 and 2005 under its 'yellow card' scheme, which doctors use to alert the agency to patients suffering worrying side-effects to a drug.
Twenty-one involved 'psychiatric disorders', 13 were of 'nervous system disorders' and eight involved 'injury, poisoning and procedural' issues.
Problems involving zolpidem have also emerged in America, where some people have been injured by cars driven by people under the influence of the drug, known there as Ambien.
In one high-profile case last year, Representative Patrick Kennedy, son of veteran senator Edward Kennedy, crashed his car into a traffic barrier on Capitol Hill at 3am. He told police that he had been going to vote at the House of Representatives. Kennedy said that he had been taking Ambien and another drug, and had become 'disorientated from the medication'.
In another case, Sean Joyce, a British painting contractor, caused havoc on a flight from North Carolina to London after taking an Ambien pill and two glasses of wine. His behaviour caused the flight to be diverted to Boston and he was later jailed for five days.
Health experts last night voiced alarm about zolpidem, which was prescribed 674,500 times in 2005 in Britain. Of those, 46,800 were for Stilnoct, the name for one of the six versions of zolpidem available in the UK and the drug implicated in the 182 episodes reported on by Australia's Adverse Drug Reactions Advisory Committee.
Professor Mayur Lakhani, chairman of the Royal College of General Practitioners, said: 'I'm concerned to hear about these instances in Australia and the 68 yellow card flaggings by our MHRA, especially as there's an increasing use of hypnotic drugs in this country. It's not the sort of thing you can ignore. We need to be vigilant, to monitor things closely and be careful how we prescribe and take this whole class of drugs.
'GPs should think carefully before they prescribe anything like this, and prescribe it for as short a time as possible, as the guidelines say. The trouble is that there are few alternative treatments for insomnia.'
Labour MP Howard Stoate, who is also a GP in Kent and the only practising GP in the Commons, said: 'I have heard of this problem with zolpidem. It's a matter of great concern. If people are operating machinery, or driving their cars, or doing skilled jobs, you wouldn't want them to be under the influence of anything that would alter their mental state, as drugs such as this do. That could be catastrophic.'
Stoate, a member of the Commons Health Select Committee, added: 'A common impression of sleeping medications is that these things are fairly mild and fairly harmless, and that's a mistake. These drugs all have problems.'
Vanessa Bourne, a spokesman for the Patients Association, said: 'Many of us are only alive because of modern drugs, so it is vital that patients have confidence not just in the drugs themselves, but in the regulatory systems that govern their use.'
An MHRA spokesman said that, as the accompanying information leaflet for both prescribers and users of Stilnoct already warns of possible side-effects including nightmares, night restlessness, sleepwalking, hallucinations and other problems, it was not necessary to conduct any inquiry into the drug or the advice that goes with it.
Drug giant Sanofi Aventis, which makes Stilnoct, said it had not been proved in the Australian cases that the drug was causing the incidents of disturbed sleep behaviour.
