JWH-138 (ÃÂ<sup>8</sup>-THC-Octyl, ÃÂ<sup>8</sup>-THC-C8) is a synthetic cannabinoid first synthesized by Roger Adams and later studied by John W. Huffman, with a K<sub>i</sub> of 8.5nM at the CB<sub>1</sub> cannabinoid receptor.
ÃÂ<sup>9</sup>-THC-Octyl and its hydrogenated analog HHC-Octyl was synthesized and studied by Roger Adams as early as 1942, and should not be confused with the ÃÂ<sup>8</sup> analog.
The ÃÂ<sup>3</sup>/ÃÂ<sup>6a(10a)</sup> isomer was synthesised in 1941, but was found to be slightly less active than ÃÂ<sup>3</sup>-THC itself. The alternate isomer ÃÂ<sup>9</sup>-THC-C8 has also been synthesised,.
Tetrahydrocannabioctyl is sometimes referred to as THC-Octyl or THC-O, which may cause confusion with THC-O-acetate which is commonly known as THC-O on packaging for grey market vaping liquids sold for use in humans. Both ÃÂ8 and ÃÂ9 (C8)-THC have been sold as designer drugs, first identified in Denmark in August 2024.
Both the ÃÂ<sup>8</sup> and ÃÂ<sup>9</sup> isomers are included within the definition of an "intoxicating cannabinoid" in Colorado under the name tetrahydrocannabioctyl, but it is unclear if it has been identified as a natural product.