About Dibucaine Amide type most potent and toxic long-acting local anaesthetic. Mechanism of Action of Dibucaine Dibucaine is a local anesthetic. It works by blocking the pathway of pain signals along nerves. It inhibits conduction of nerve impulses and decreases cell membrane permeability to ions at the site of the pain. This prevents an electrical signal building up and passing along the nerve fibres to the brain. In this way Dibucaine causes numbness and relieves pain at the area it is applied to.