Remifentanil is a potent ultra short-acting synthetic opioid given to patients during surgery for pain relief and adjunctive to an anaesthetic. Remifentanil is a specific mu-type-opioid receptor agonist which acts in the brain, spinal cord, and peripherally. This means it reduces sympathetic nervous system tone, and causes respiratory depression and analgesia. Remifentanil binds to mu opioid receptors, stimulating the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as GABA is inhibited. Opioids close N-type voltage-operated calcium channels and open calcium-dependent inwardly rectifying potassium channels. This results in hyperpolarization and reduced neuronal excitability. This leads to less activity in the brain which causes an anesthetic effect.

Remifentanil Opioid Anasthetic Pathway References