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Pathway Description
Alfentanil Opioid Agonist Action Pathway
Homo sapiens
Drug Action Pathway
Alfentanil is used to induce and maintain anesthesia, as well as an analgesic.
Alfentanil is a short-acting opioid anesthetic and analgesic derivative of fentanyl. It produces an early peak analgesic effect and fast recovery of consciousness. Alfentanil is effective as an anesthetic during surgery, for supplementation of analgesia during surgical procedures, and as an analgesic for critically ill patients. Alfentanil is a synthetic opioid analgesic. Alfentanil interacts predominately with the opioid mu-receptor. These mu-binding sites are discretely distributed in the human brain, spinal cord, and other tissues. In clinical settings, alfentanil exerts its principal pharmacologic effects on the central nervous system. Its primary actions of therapeutic value are analgesia and sedation. Alfentanil may increase the patient's tolerance for pain and decrease the perception of suffering, although the presence of the pain itself may still be recognized. In addition to analgesia, alterations in mood, euphoria and dysphoria, and drowsiness commonly occur. Alfentanil depresses the respiratory centers, depresses the cough reflex, and constricts the pupils.
Alfentanil binds on pre-synaptic mu opioid receptors. Opiate receptors are coupled with G-protein receptors and function as both positive and negative regulators of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates 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. Less GABA leads to disinhibition of dopamine cell firing in the spinal cord pain transmission neurons. This leads to less pain signaling and analgesia. Opioids close N-type voltage-operated calcium channels and open calcium-dependent inwardly rectifying potassium channels. This results in hyperpolarization and reduced neuronal excitability. Alfentanil has many sites of action where it can act on mu opioid receptors. The inhibition of A delta and C pain fibres in the dorsal horn of the spinal cord is very important as it slows the signaling of pain into the spinal cord. Alfentanil can also be used for treating cough. Symptoms of overexposure include characteristic rigidity of the skeletal muscles, cardiac and respiratory depression, and narrowing of the pupils.
References
Alfentanil Opioid Agonist Pathway References
Chan P, Lufty K. Molecular Changes in Opioid Addiction: The Role of Adenylyl Cyclase and cAMP/PKA System. Progress in Molecular Biology and Translational Science, Volume 137: 203-219, 2016.
Nassirpour R, Bahima L, Lalive AL, Luscher C, Lujan R, Slesinger PA: Morphine- and CaMKII-dependent enhancement of GIRK channel signaling in hippocampal neurons. J Neurosci. 2010 Oct 6;30(40):13419-30. doi: 10.1523/JNEUROSCI.2966-10.2010.
Pubmed: 20926668
Wishart DS, Feunang YD, Guo AC, Lo EJ, Marcu A, Grant JR, Sajed T, Johnson D, Li C, Sayeeda Z, Assempour N, Iynkkaran I, Liu Y, Maciejewski A, Gale N, Wilson A, Chin L, Cummings R, Le D, Pon A, Knox C, Wilson M: DrugBank 5.0: a major update to the DrugBank database for 2018. Nucleic Acids Res. 2018 Jan 4;46(D1):D1074-D1082. doi: 10.1093/nar/gkx1037.
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