Benzodiazepines, commonly known as benzos and used to treat anxiety and sleep problems, are now considered the number-one drug problem by many community groups and are typically combined with other substances.
The booming market is being supplied through over-prescription by some GPs, mass importation either physically or online, and back-street manufacture.
The situation inside prisons has traditionally been harder to grasp, with limited information from prison authorities and little independent research.
However, two sets of data obtained by the Irish Examiner give a glimpse into the area.
Documents released under the Freedom of Information Act show the amount spent by the Irish Prison Service (IPS) on pharmaceuticals has risen over the last seven years.
In 2004, the bill came to €2.4m. This figure remained generally stable until 2008, before jumping to €2.8m in 2009 and to €2.96m in 2010.
The vast bulk of the budget is spent providing medication to treat anxiety, depression, psychosis, HIV, and drug addiction among inmates.
The rise in the budget corresponds with a jump in the prison population, from 3,199 in 2004 to 4,290 in 2010.
Taking prisoner numbers into account, the average cost per inmate per year rose between 2004 and 2006, when it peaked at €805, before falling in 2007 and 2008, rising again in 2009 and dropping back in 2010. Overall, the average cost fell from €760 in 2004 to €690 in 2010.
Comparisons between individual prisons for the period are not possible from the data provided by the IPS, with the only comparable figures being limited to 2009 and 2010.
The same four prisons (Dóchas, Arbour Hill, Wheatfield, and Midlands) feature in the top five jails in 2009 and 2010 for consumption levels per inmate.
Dóchas women’s prison has the highest consumption levels, with the average cost hitting nearly €960 in 2010, followed by Arbour Hill (€810), the main jail for sex offenders.
Wheatfield, Portlaoise, and Castlerea prisons come after.
The documents do not provide a breakdown between the different types of medication, but a significant proportion of the bill is thought to be from benzodiazepines.
Antiretroviral drugs used to treat HIV are expensive and account for about 25% of the bill.
A second set of prison data, compiled by the Health Research Board, also shows a high level of benzodiazepine use, this time among inmates in, or seeking, drug treatment.
While the data doesn’t say whether usage is based on prescription or is supplied illegally into prisons, Dr Jean Long of the HRB believes it is “mostly prescription”, in part because security procedures have cut down illegal supplies into the system.
“Benzodiazepines are a major problem inside and outside in the community,” said Dr Long. “It is a drug used to treat anxiety, but the problem is if used over the long term you can develop a new addiction. There has got to be better ways to manage anxiety.
“We need to look at why so many people are on benzodiazepines. Are there other options to manage these people better, rather than compounding addictions? We need more therapy than medication.”
Dr Long said the figures suggested a “big improvement” in the reduction of illegal drug use generally, particularly in relation to heroin and cocaine, although the figures for cannabis erre relatively high across prisons, particularly in Mountjoy, Loughan House, and Castlerea.
Dr Long said access to drug treatment had “increased phenomenally” and commended this.
Dr Joe Barry, a public health specialist and lecturer in Trinity College Dublin, said the staff levels were not there in prisons to provide therapy.
He added: “If you really want to reduce the cost of the drug bill you need to change sentencing policy and reduce the number of people with primarily mental health issues going to prison. That’s the single biggest take-home message from these figures.”