Medical specialists warned the Government they had serious reservations about expanding the role of drug-buying agency Pharmac, saying some aspects could prove to be a nightmare.
Clinicians' concerns are detailed in a report on consultations carried out with them about the plan to have Pharmac manage all hospital as well as community medicines.
The specialists say they realise the need for national consistency and cost-effectiveness, but say putting Pharmac in charge of all hospital medicines could restrict their treatment decisions.
They also say say Pharmac takes too long to approve drugs, isn't open and may ignore expert advice.
Health Minister Tony Ryall says the move will end inconsistencies between regions in the drugs patients are able to get through their local district health board.
Pharmac already manages cancer drugs and some off-patent drugs used in hospitals and will now take over management of $215 million of other hospital drugs every year.
In addition, it is to begin taking over the assessment and purchase of all medical devices used in hospitals, beginning with insulin pumps.
Mr Ryall says changes to the buying of medical devices will be made slowly in order to retain doctors' confidence in the process.