Background:

IC50: 0.8-1.5 nM for rat and human 5-HT2 receptor

AL 34662 is a potent 5-HT2 receptor agonist.

SEROTONIN (5-hydroxytryptamine; 5-HT) is a major neurotransmitter in the central nervous system (CNS) of mammals and has welldocumented physiological functions in numerous cells, tissues, and organs.

In vitro: AL-34662 exhibited a high affinity for the rat and human 5-HT2 receptor and for cloned human 5-HT2A-C receptors. AL-34662 stimulated phosphoinositide turnover in human ciliary muscle and in human trabecular meshwork cells. AL-34662 also mobilized intracellular Ca2+ in h-CM and h-TM cells, being a full agonist like 5-HT itself. AL-34662's effects in the h-CM cells were potently antagonized by 5-HT2A-antagonist M-100907, but weakly by 5-HT2B-antagonist, 5-HT2B/C- antagonist and 5-HT2C antagonist. Moreover, it was found that the (R)-enantiomer (AL-34707) and the racemate (AL-34497) were less potent and/or efficacious than AL-34662 in all of these assays [1].

In vivo: AL-34662 caused relatively minimal ocular discomfort and hyperemia in rabbit and guinea pig eyes. It efficaciously lowered intraocular pressure in the conscious ocular hypertensive monkey eyes [1].

Clinical trial: So far, no clinical study has been conducted.

Reference:
[1] Sharif NA, McLaughlin MA, Kelly CR.  AL-34662: a potent, selective, and efficacious ocular hypotensive serotonin-2 receptor agonist. J Ocul Pharmacol Ther. 2007 Feb;23(1):1-13.