Stopping the use of certain tranquillisers in prisons and hospitals reduces the levels of violence and self-harm and helps raise health standards, according to the country’s leading forensic psychiatrist.

Harry Kennedy, head of the Central Mental Hospital, said that since they stopped prescribing the medication in their prison clinics, the suicide rates there had fallen.

He said in the CMH, the most violent patients in the State are now managed without BZDs, a group name for tranquillisers commonly known as benzos.

Prof Kennedy’s statement comes as the Department of Health continues to draft laws to impose additional controls on BZDs and hypnotics known as Z-drugs.

The measures are being brought in to deal with both legal over-prescribing of the drugs by GPs and psychiatrists, and the massive illicit sale of the drugs, fuelled by a booming online trade.

Recent figures from a population survey found a lifetime prevalence (ever used) of tranquillisers and sedatives of 13.9% in 2011, compared to 10.5% in 2007. Last year usage (recent use) was 6.5%, up from 4.7%. Research among those in drug treatment in prisons found that 27% were on BZD medication, rising to a high of 44% in Mountjoy and 54% in Dochas.

Writing in the journal Psychiatry Professional, Prof Kennedy said determined efforts to end the prescription of BZDs had huge benefits.

"In our experience, eliminating the use of all BZDs in prisons and in hospital settings improves therapeutic engagement and motivation, eliminates drug seeking from the therapeutic process and reduces violence and repetitive self-harm when combined with effective nursing and multidisciplinary care," he said.

Unlike many other psychiatric settings, said Prof Kennedy