Mechanism of Action in Healthcare

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The term mechanism of action is a pharmacological term that you commonly hear associated with medications or drugs. Let's gain an understanding of what mechanism of action means, and provide examples within the context of health conditions.


Mechanism of action refers to the biochemical process through which a drug produces its effect. Drugs bind to receptors, which are located on the surface of cells or within a cell's cytoplasm — a jelly-like substance within a cell.

When bound, the drug can act as either an agonist or an antagonist. Agonist drugs activate the receptors they bind to, which either increases or decreases activity within the cell. Antagonist drugs, on the other hand, block the receptors so that natural agonists within the body cannot bind.

Most drugs bind to a specific type of receptor, and this term is called receptor selectivity. The ability of a drug to bind to a certain receptor is based on its unique chemical structure.


The mechanism of action of a medication is the specific biological process through which the medication causes a reduction in symptoms. For example, the mechanism of action of selective serotonin reuptake inhibitors, or SSRIs, is well known. SSRIs inhibit the reuptake of serotonin. This increases the level of serotonin in the brain, which improves a person's mood.

For some drugs, the mechanism of action is unknown—so the drug works, but scientists are not sure exactly how it creates its therapeutic effect. An example of a medication with an unknown mechanism of action is lithium, a mood stabilizer used in the treatment of bipolar disorder. Other drugs have multiple known mechanisms of action, like caffeine.

More on Mechanism of Action

Sometimes the term mechanism of action is used to describe a non-drug treatment. For example, the mechanism of action of a psychosocial intervention—like psychotherapy—is the specific intervention that produces a change in a patient's symptoms. Experts propose that the mechanism of action of psychotherapy is based on the patient-therapist interaction, and how actively they participate in sessions.

What This Means for You

It's a good idea to understand the mechanism of action of any therapy you are receiving. This may help you conceptualize how the medication or therapy is supposed to help you get better.

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Article Sources

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