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Tuesday, January 10, 2017

Tapentadol



🚩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.

NB

🔻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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