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Mechanisms of Drug Action - Coggle Diagram
Mechanisms of Drug Action
Physical Mechanisms
Drug does not produce any chemical reaction or change in the cells of the body.
The effect is only physical.
Chemical Mechanisms
Drugs act by producing chemical reactions in the body.
Drug-Receptor Interactions
Drugs act on the cell membrane by physical and/or chemical interactions.
They usually act through specific drug receptor sites located on the membrane
Receptor: the specific chemical constituents of the cell which a drug interacts with to produce a pharmacological effect.
This binding can be reversible or irreversible.
When a drug binds to the receptor, the response gradually increases until it reaches the peak, and then the response decreases. The reason for desensitisation is unclear.
Drug-Enzyme Interactions
Drugs act within the cell by modifying normal biochemical reactions. The drugs resemble the natural substrate, bind and cause change in their normal activity.
This may take place by activation or inhibition of enzymes.
The competition of drugs with enzymes may be competitive or non-competitive inhibition.
Drug-Channel Interactions
Drugs interfere with the flow of ions through specific channels.
e.g. sodium ion channels, potassium ion channels, calcium ion channels and chloride channels
Miscellaneous Mechanisms
Some drugs do not act through any of the other categories, therefore are categorised as miscellaneous.
Some drugs act exclusively outside of cells, such as the external surfaces of skin and gastrointestinal tract. This is a good example of drugs acting outside of the cells by physical means.
Neutralisation of the stomach acid by antacids is an example of drugs acting outside of cell membranes by chemical interactions.