Synthetic cannabinoid EG-018 showed unusual properties as a weak partial agonist at cannabinoid receptors

EG-018 had high affinity for CB1 (21 nM) and CB2 (7 nM) but behaved as a weak partial agonist, unlike typical synthetic cannabinoids. When injected into the abdomen, it produced no effects, but intravenous administration caused reduced movement, catalepsy, and hypothermia, with only catalepsy being CB1-mediated.

In vitro binding studies at human CB1 and CB2 receptors in HEK293 cells. In vivo testing in mice using the cannabinoid tetrad (hypomotility, catalepsy, hypothermia, analgesia) and THC drug discrimination via both intraperitoneal and intravenous administration.

EG-018 has been detected in illicit products and human samples, so understanding its pharmacology is important for toxicology and public health. Its unusual partial agonist profile distinguishes it from more dangerous full-agonist synthetic cannabinoids.

The fact that EG-018 has high receptor affinity but low efficacy makes it pharmacologically distinct from full-agonist synthetic cannabinoids like JWH-018, which may have implications for understanding how different cannabinoids produce different effects.

The lack of effect via intraperitoneal administration suggests pharmacokinetic issues (possibly rapid metabolism) that complicate interpretation. Only basic behavioral assays were used.