Drug Action: How Drugs Act on Receptors

Many cells have specialized areas, known as receptors, on their outer walls. Natural chemical messengers, such as hormones, bind with these receptors to produce changes in cells and thereby affect body processes. In order to treat some disorders, it may be necessary to increase or decrease the effect of a particular natural chemical. Drugs called agonists bind with specific receptors to produce an effect similar to that of the natural chemical. Antagonist drugs inhibit the effect of the chemical by blocking the receptors.

Agonist drugs

An agonist drug mimics the action of body chemicals. It occupies an empty receptor and enhances the natural chemical’s effect.

Antagonist drugs

An antagonist drug occupies cell receptors, preventing the body chemicals from binding to them, thereby inhibiting their action.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

Back to top