About Fentanyl Citrate Synthetic primary opioid agonist, Anilidopiperidine derivative, Narcotic analgesic, General Anesthetic. Mechanism of Action of Fentanyl Citrate This drug primarily acts on the CNS. Fentanyl is a pure Opioid agonist and primarily acts on the mu Opioid receptors located in brain, spinal cord, and in smooth muscles. This action causes alteration of pain perception in patients, thus providing analgesia. It has some hypnotic activity. It causes histamine release rarely. Indications for Fentanyl Citrate 1. Adjunct to anesthesia 2. Induction and maintenance of anesthesia 3. Post operative analgesic 4. Pre operative analgesic 5. Chronic pain Interactions for Fentanyl Citrate CNS depresants, neuroleptics, narcotic anlgesics, nitrous oxide, conduction anaesthetics.