The Health Service Executive has urged chemists to resume their services to methadone patients.
Members of the Irish Pharmaceutical Union have withdrawn services to methadone patients in a row over a new drug payment structure.
The Merchants Quay project has criticised the action saying vulnerable people will suffer.
The General Secretary of the Irish Pharmaceutical Union has said there has been a total breakdown in trust between the HSE and pharmacists.
Speaking to RTÉ News, Seamus Feely said they are available for talks with the HSE, but those talks must address all issues, including pharmacists' right to union recognition, plans to cut the mark-up on the wholesale cost of drugs and also the administration of the methadone scheme.
His comments come as more than 140 pharmacies pulled out of the HSE's methadone protocol today. Pharmacists have stopped dispensing to 3,000 methadone patients.
Earlier, the head of the Health Service Executive pharmaceutical office urged pharmacists to resume services to methadone patients.
Professor Kamal Sabra said the HSE would do anything to resolve the situation. However, he said it could not negotiate fees with the IPU as this would be in breach of competition law.
The HSE says the new arrangements will slash an estimated €100m off the State's drugs bill next year, but pharmacists say it will result in them having to dispense medicine to public patients at a loss and put their businesses at risk.
As a result of the pharmacists' action, former heroin users who had been receiving methadone from a chemist are being told to attend a drugs clinic instead.
The HSE says all clients affected have been contacted and emergency methadone services are being provided at 11 sites.
Information about the contingency arrangements is available on the HSE's Drug Helpline (1800 459 459).
The action is mainly confined to Dublin but the HSE says it is monitoring the situation nationwide.
