STS-135 (N-(adamantan-1-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide, also called 5F-APICA) is a designer drug offered by online vendors as a cannabimimetic agent.

The structure of STS-135 appears to use an understanding of structure-activity relationships within the indole class of cannabimimetics, although its design origins are unclear.

[2] STS-135 produces bradycardia and hypothermia in rats at doses of 1–10 mg/kg, suggesting cannabinoid-like activity.

[2] As of October 2015 STS-135 is a controlled substance in China.

A forensic standard of STS-135 is available, and the compound has been posted on the Forendex website of potential drugs of abuse.