5-Carboxamidotryptamine (5-CT), also known as 5-(aminocarbonyl)tryptamine, is a tryptamine derivative closely related to the neurotransmitter serotonin.
5-CT acts as a non-selective, high-affinity full agonist at the 5-HT<sub>1A</sub>, 5-HT<sub>1B</sub>, 5-HT<sub>1D</sub>, 5-HT<sub>5A</sub>, and 5-HT<sub>7</sub> receptors, as well as an agonist of the 5-HT<sub>2</sub>, 5-HT<sub>3</sub>, 5-HT<sub>6</sub> receptors with lower affinity. It has negligible affinity for the 5-HT<sub>1E</sub> and 5-HT<sub>1F</sub> receptors. 5-CT binds most strongly to the 5-HT<sub>1A</sub> receptor and it was once thought to be selective for this site.
In 2018, a close derivative of 5-CT, AH-494 has been shown to function as an agonist of 5-HT7, although being more selective over 5-HT1A. Structural study indicated residue Ser5x43 might play critical roles in the selectivity of 5-CT across the serotonin receptor family.