RCS-8, or 1--3-(2-methoxyphenylacetyl)indole, is a synthetic cannabinoid also known as SR-18 or BTM-8, which has been found as an ingredient of "herbal" synthetic cannabis blends. It can be described as an analogue of JWH-250

JWH-250

JWH-250 or is an analgesic chemical from the phenylacetylindole family, which acts as a cannabinoid agonist at both the CB1 and CB2 receptors, with a Ki of 11nM at CB1 and 33nM at CB2...

 with the 1-pentyl group replaced by 1-(2-cyclohexylethyl), and can be expected to be less potent than JWH-250 (cf. JWH-007

JWH-007

JWH-007 is an analgesic chemical from the naphthoylindole family, which acts as a cannabinoid agonist at both the CB1 and CB2 receptors. It was the most active of the first group of N-alkyl naphoylindoles discovered by the team led by John W Huffman, several years after the family was initially...

 and its cyclohexylethyl analogue). Despite not having been reported in the scientific or patent literature as yet, reputed recreational use of RCS-8 in the United States has led to it being specifically listed in a proposed 2011 amendment to the Controlled Substances Act

Controlled Substances Act

The Controlled Substances Act was enacted into law by the Congress of the United States as Title II of the Comprehensive Drug Abuse Prevention and Control Act of 1970. The CSA is the federal U.S. drug policy under which the manufacture, importation, possession, use and distribution of certain...

, aiming to add a number of synthetic drugs into Schedule I.