🚩Is a new centrally acting analgesic that relies on a dual mechanism of action. These are mu opioid receptor agonism and norepinephrine (noradrenaline) reuptake inhibition 
🚩It is therefore not a classical opioid, but represents a unique class of analgesic drug (MOR-NRI). 
🚩It is now registered for use in the treatment of moderate to severe chronic pain that proves unresponsive to conventional non-narcotic medications in many countries. 
🚩Tapentadol has a much lower affinity (20 times less) to the mu receptor than morphine, but its analgesic effect is only around three times less than morphine. 
🚩This discrepancy is explained by its inhibitory effect on norepinephrine reuptake, strengthening descending inhibitory pathways of pain control 
🚩Tapentadol is seen by some as similar to tramadol, but differs in a number of important points:
▶️It is not a racemic mixture of two enantiomers with different pharmacological effects
▶️Has no active metabolites (which are relevant for tramadol’s mu opioid receptor agonism) 
▶️Has only minimal serotonin effects
🚩This means that interactions with other serotonergic drugs (such as anti-depressants) are unlikely, reliance on metabolism by the cytochrome P450 system for increased efficacy is not required and retention of active metabolites causing potential adverse effects is not a concern. 


🔻Tramadol is a 4 phenyl piperidine analogue of codeine
🔻It has a weak central action at opioid receptors
🔻And also on descending monaminergic pathways (also responsible for the side effects)
🔻Hence known as an atypical centrally acting opioid
🔻It’s M1 metabolite has more affinity to opioid receptors than parent compound 
🔻So metabolites are important in maintaining efficacy
#Opioids , #Pharmacology , #analgesia , #PalliativeCare , #Pain , #SideEffects , #NewDrugs , #medicine , #anaesthesia
Reference: Recent advances in the pharmacological management of acute and chronic pain Stephan A. Schug, Catherine Goddard, Annals of Palliative Medicine, Vol 3, No 4 October 2014


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