Antagonist: Difference between revisions
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Pharmacological antagonists can be further characterised as: | Pharmacological antagonists can be further characterised as: | ||
*[[Competitive antagonists|Competitive]] which binds to the binding site of a receptor - via the induced fit method - and can be overcome by increasing the concentration of an [[Agonist|agonist]] (competitor). Example: Atropine, Tropicamide, Hyoscine (all these bind to muscarinic receptors)<ref>Rang, H. and Dale, M. (2012). Rang and Dale's pharmacology. Edinburgh: Elsevier/Churchill Livingstone pg160</ref><br> | *[[Competitive antagonists|Competitive]] which binds to the binding site of a receptor - via the induced fit method - and can be overcome by increasing the concentration of an [[Agonist|agonist]] (competitor). Example: Atropine, Tropicamide, Hyoscine (all these bind to muscarinic receptors)<ref>Rang, H. and Dale, M. (2012). Rang and Dale's pharmacology. Edinburgh: Elsevier/Churchill Livingstone pg160</ref><br> | ||
*[[Irreversible competitive antagonist|Irreversible competitive]] which forms a [[Covalent bond|covalent bond]] with the receptor. | *[[Irreversible competitive antagonist|Irreversible competitive]] which forms a [[Covalent bond|covalent bond]] with the receptor. | ||
*[[Non-competitive antagonist|Non-competitive antagonists]] which blocks the [[Signal transduction|signal transduction]] event of the [[Receptor|receptor]]. | *[[Non-competitive antagonist|Non-competitive antagonists]] which blocks the [[Signal transduction|signal transduction]] event of the [[Receptor|receptor]]. There term non-competitive antagonists are used to describe two different situations : one where the antagonist binds to the allosteric site of the receptor itself and the other is when the antagonist binds to the active site of the receptor<sup>(2)</sup>. | ||
A pharmacalogical example of an antagonist is [[Tamoxifen|Tamoxifen]], a drug which acts on [[Oestrogen|estrogen]] receptor. | A pharmacalogical example of an antagonist is [[Tamoxifen|Tamoxifen]], a drug which acts on [[Oestrogen|estrogen]] receptor. | ||
See also [[Agonist|agonist]]. | See also [[Agonist|agonist]]. | ||
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=== References === | === References === | ||
<references /> | <references /> | ||
2. Golan D. Principles of Pharmacology [Internet]. Google Books. 2016 [cited 20 October 2016]. Available from: [https://books.google.com.my/books?id=az8uSDkB0mgC&pg=PA23&lpg=PA23&dq=noncompetitive+active+site+antagonist&redir_esc=y&hl=en#v=onepage&q&f=false https://books.google.com.my/books?id=az8uSDkB0mgC&pg=PA23&lpg=PA23&dq=noncompetitive+active+site+antagonist&redir_esc=y&hl=en#v=onepage&q&f=false] | |||
Revision as of 02:25, 20 October 2016
A compound (usually synthetic) that inhibits the action of its natural counterpart by binding to a receptor or protein. There are three classes of antagonist, chemical, physiological and pharmacological.
Pharmacological antagonists can be further characterised as:
- Competitive which binds to the binding site of a receptor - via the induced fit method - and can be overcome by increasing the concentration of an agonist (competitor). Example: Atropine, Tropicamide, Hyoscine (all these bind to muscarinic receptors)[1]
- Irreversible competitive which forms a covalent bond with the receptor.
- Non-competitive antagonists which blocks the signal transduction event of the receptor. There term non-competitive antagonists are used to describe two different situations : one where the antagonist binds to the allosteric site of the receptor itself and the other is when the antagonist binds to the active site of the receptor(2).
A pharmacalogical example of an antagonist is Tamoxifen, a drug which acts on estrogen receptor.
See also agonist.
References
- ↑ Rang, H. and Dale, M. (2012). Rang and Dale's pharmacology. Edinburgh: Elsevier/Churchill Livingstone pg160
2. Golan D. Principles of Pharmacology [Internet]. Google Books. 2016 [cited 20 October 2016]. Available from: https://books.google.com.my/books?id=az8uSDkB0mgC&pg=PA23&lpg=PA23&dq=noncompetitive+active+site+antagonist&redir_esc=y&hl=en#v=onepage&q&f=false