Onternabez (also known as HU-308, HU308, PPP-003, and ARDS-003) is a synthetic cannabinoid that acts as a potent cannabinoid agonist. It is highly selective for the cannabinoid-2 receptor (CB<sub>2</sub> receptor) subtype, with a selectivity more than 5,000 times greater for the CB<sub>2</sub> receptor than the CB<sub>1</sub> receptor. The synthesis and characterization of onternabez took place in the laboratory of Raphael Mechoulam at the Hebrew University of Jerusalem (the HU in HU-308) in the late 1990s. The pinene dimethoxy-DMH-CBD derivative onternabez was identified as a potent peripheral CB<sub>2</sub>-selective agonist in in vitro and animal studies in 1990 and 1999.
Onternabez is non-psychoactive and not scheduled at the federal level in the United States. It is a Schedule I controlled substance in the state of Florida making it illegal to buy, sell, or possess there.