Org 27569 is a drug which acts as a potent and selective allosteric modulator of the cannabinoid CB₁ receptor

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

. Studies in vitro suggest that it binds to a regulatory site on the CB₁ receptor target, causing a conformational change that increases the binding affinity of CB₁ agonists such as CP 55,940

CP 55,940

CP 55,940 is a cannabinoid which mimics the effects of naturally occurring THC . CP 55,940 was created by Pfizer in 1974 but was never marketed. It is currently used to study the endocannabinoid system...

, while decreasing the binding affinity of CB₁ antagonists or inverse agonists such as rimonabant

Rimonabant

Rimonabant is an anorectic antiobesity drug that has been withdrawn from the market. It is an inverse agonist for the cannabinoid receptor CB1...

. However while Org 27569 increases the ability of CB₁ agonists to bind to the receptor, it decreases their efficacy at stimulating second messenger signalling once bound, and so in practice behaves as an insurmountable antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

of CB₁ receptor function.