The number of people seeking treatment for an addiction to benzodiazepines has more than doubled since 2009, figures from the Health Service Executive have shown.

The increase in use of the psychoactive drug, which has been implicated in hundreds of deaths in recent years, has been described as a major cause for alarm by an addiction services expert.

The most recent statistics show benzodiazepines were the main problem drug of 547 people who sought treatment for substance abuse in 2012, compared with 261 in 2009.

Benzodiazepines are sedatives that are often prescribed by doctors for the treatment of anxiety and insomnia, but recreational misuse of the drug has become increasingly common.

Dr Garrett McGovern, a GP who specialises in the treatment of alcohol and substance abuse, said the increase in misuse of the potentially lethal drug was a worrying development.

"The statistics are a major cause for alarm. We have not got a handle on this at all due to a lack of expertise in the area and an unwillingness within government to invest in treatment," he said.

Dangerous

"Using benzos in an unstructured manner with alcohol and other CNS (central nervous system) depressants is dangerous, but the risk of overdose is not uniform - many different users can take the same quantity of drugs but not all of them will suffer a fatal overdose."

According to the Health Research Board's (HRB) National Drug-Related Deaths Index, benzodiazepines were implicated in 166 deaths in 2011 and 103 in 2010. They were also involved in more deaths by poisoning than any other substance between 1998 and 2008.

Tony Duffin, director of the Ana Liffey Drug Project, suggested the increase in misuse of benzodiazepines in recent years may be linked to the closure of headshops in 2010.

"Once headshop drugs were restricted via the legislation there was a shift away from the headshop drugs back to the more traditional substances of choice - notably heroin and benzodiazepines," he said.

The statistics relating to the number of people seeking treatment for substance abuse was revealed in response to a parliamentary question by Galway West TD Brian Walsh.