PB-22

PB-22 (QUPIC or 1-pentyl-1H-indole-3-carboxylic acid 8-quinolinyl ester) is a designer drug offered by online vendors as a cannabimimetic agent, and detected being sold in synthetic cannabis products in Japan in 2013. The structure of PB-22 appears to use an understanding of structure-activity relationships within the indole class of cannabimimetics, although its design origins are unclear. PB-22 represents a structurally unique synthetic cannabinoid chemotype, since it contains an ester linker at the indole 3-position, rather than the precedented ketone of JWH-018 and its analogs, or the amide of APICA and its analogs.

PB-22 has an EC₅₀ of 5.1 nM for human CB₁ receptors, and 37 nM for human CB₂ receptors. PB-22 produces bradycardia and hypothermia in rats at doses of 0.3–3 mg/kg, suggesting potent cannabinoid-like activity. The magnitude and duration of hypothermia induced in rats by PB-22 was notably greater than JWH-018, AM-2201, UR-144, XLR-11, APICA, or STS-135, with a reduction of body temperature still observable 6 hours after dosing. One clinical toxicology study found PB-22 to be the cause of seizures in a human and his dog.