pharmacology Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemi ...

, partial agonists are drugs that bind to and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist. They may also be considered ligands which display both

agonistic An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agoni ...

and antagonistic effects—when both a full agonist and partial agonist are present, the partial agonist actually acts as a competitive antagonist , competing with the full agonist for receptor occupancy and producing a net decrease in the receptor activation observed with the full agonist alone. Clinically, partial agonists can be used to activate receptors to give a desired submaximal response when inadequate amounts of the endogenous ligand are present, or they can reduce the overstimulation of receptors when excess amounts of the endogenous ligand are present. Some currently common drugs that have been classed as partial agonists at particular receptors include buspirone, aripiprazole, buprenorphine,

nalmefene Nalmefene is an opioid antagonist medication used in the management of opioid overdose and alcohol dependence. It is taken by mouth. Nalmefene is an opiate derivative similar in both structure and activity to the opioid antagonist naltrexone. ...

and

norclozapine ''N''-Desmethylclozapine (NDMC), or norclozapine, is a major active metabolite of the atypical antipsychotic drug clozapine. Unlike clozapine, it possesses intrinsic activity at the D2/ D3 receptors, and acts as a weak partial agonist at these ...

. Examples of ligands activating peroxisome proliferator-activated receptor gamma as partial agonists are honokiol and falcarindiol. Delta 9-tetrahydrocannabivarin ( THCV) is a partial agonist at CB2 receptors and this activity might be implicated in ∆9-THCV-mediated

anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as ...

effects. Additionally, Delta-9-Tetrahydrocannabinol ( THC) is a partial agonist at both the CB1 and CB2 receptors, with the former being responsible for its psychoactive effects.

References

Pharmacodynamics {{pharmacology-stub

See also

References