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|Atropine]], [[Tropicamide|Tropicamide]], [[Hyoscine|Hyoscine]] (all these bind to [[ | *[[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|Atropine]], [[Tropicamide|Tropicamide]], [[Hyoscine|Hyoscine]] (all these bind to [[Muscarinic receptor|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]]. 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<ref>Golan D. Principles of Pharmacology [Internet]. Google Books. 2016 [cited 20 October 2016]. Available from: https://books.google.com.my/books?id=az8uSDkB0mgC&amp;pg=PA23&amp;lpg=PA23&amp;dq=noncompetitive+active+site+antagonist&amp;redir_esc=y&amp;hl=en#v=onepage&amp;q&amp;f=false</ref>. | *[[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<ref>Golan D. Principles of Pharmacology [Internet]. Google Books. 2016 [cited 20 October 2016]. Available from: https://books.google.com.my/books?id=az8uSDkB0mgC&amp;amp;pg=PA23&amp;amp;lpg=PA23&amp;amp;dq=noncompetitive+active+site+antagonist&amp;amp;redir_esc=y&amp;amp;hl=en#v=onepage&amp;amp;q&amp;amp;f=false</ref>. | ||
A pharmacalogical example of an antagonist is [[Tamoxifen|Tamoxifen]], a drug which acts on [[Oestrogen|estrogen]] receptor and is often used in the treatment of breast cancer. | |||
Chemical antagonism occurs when the drug in question causes an effect by preventing the formation of a chemical compound. | |||
See also [[Agonist|agonist]].<br> | See also [[Agonist|agonist]].<br> | ||
Revision as of 12:53, 24 October 2017
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 and is often used in the treatment of breast cancer.
Chemical antagonism occurs when the drug in question causes an effect by preventing the formation of a chemical compound.
See also agonist.
References
- ↑ Rang, H. and Dale, M. (2012). Rang and Dale's pharmacology. Edinburgh: Elsevier/Churchill Livingstone pg160
- ↑ Golan D. Principles of Pharmacology [Internet]. Google Books. 2016 [cited 20 October 2016]. Available from: https://books.google.com.my/books?id=az8uSDkB0mgC&amp;pg=PA23&amp;lpg=PA23&amp;dq=noncompetitive+active+site+antagonist&amp;redir_esc=y&amp;hl=en#v=onepage&amp;q&amp;f=false