A substituted pyridopyrroloquinoxaline, or more specifically a substituted octahydro-1H-pyrido[3',4':4,5]pyrrolo[1,2,3-de]quinoxaline, also known as a substituted heterocycle fused ó-carboline, is a further-cyclized and substituted tetracyclic derivative of the tricyclic alkaloid ó-carboline as well as an analogue of the atypical antipsychotic lumateperone. They can additionally be thought of as analogues of cyclized tryptamines like the ò-carbolines or harmala alkaloids such as harmaline, but are not technically tryptamines themselves.
Pyridopyrroloquinoxalines are notable for their varying interactions with the serotonin 5-HT<sub>2A</sub> receptor as well as with other monoamine receptors. Lumateperone and deulumateperone are serotonin 5-HT<sub>2A</sub> receptor antagonists with antipsychotic properties, IHCH-7113 is a putatively psychedelic serotonin 5-HT<sub>2A</sub> receptor full agonist with a robust head-twitch response in rodents, and IHCH-7086, IHCH-7079, and ITI-1549 are putatively non-hallucinogenic ò-arrestin-biased serotonin 5-HT<sub>2A</sub> receptor partial agonists with psychoplastogenic and/or antidepressant-like effects in preclinical studies. The broad receptor interactions of some of these compounds have been studied.
Pyridopyrroloquinoxalines with serotonin 5-HT<sub>2A</sub> receptor agonistic activity such as IHCH-7113 and IHCH-7086 were first described in the scientific literature by Dongmei Cao and colleagues by 2022. As of 2025, ITI-1549 is under development by Intra-Cellular Therapies for the treatment of mood and other psychiatric disorders.
Other known pyridopyrroloquinoxalines include IHCH-7081, IHCH-7087, IHCH-7088, IHCH-7089, IHCH-7112, and IHCH-7120.