It is understood that nine people overdosed on Friday after drugs were dropped into the prison yard.
Four of the inmates were subsequently brought to hospital, where one person currently remains in a coma.
Two prison officers were assaulted during the incident.
The prison staff have since increased the number of random cell searches and have increased the focus on searching the deliveries into prisons.
The Prison Service assures that is working with an Garda Síochána to prevent contraband entering all prisons.
The prison service has appealed to prisoners, visitors, staff or members of the public with information regarding the trafficking of contraband to contact them at the free confidential telephone line (1800 855 717) or text line (086 180 2449) .
