The use of methadone at Mountjoy jail has been criticised.
It's one of a number of issues highlighted by a visiting committee to Dublin's prisons.
Jails are still struggling to tackle drug and staffing problems according to the latest round of prison visit reports.
One study expressed severe reservations over the introduction of methadone at Mountjoy despite some success of the programme.
While Wheatfield prison was criticised for its drug related difficulties, vermin problems and its reduced library opening times.
There's also an issue with sniffer dogs at the jail targeting the wrong visitors for searches.
Its now recommended that the dog unit be sent for retraining.
