AL-34662 is an indazole derivative drug that is being developed for the treatment of glaucoma. It acts as a selective 5-HT2A receptor agonist, the same target as that of psychedelic drugs like psilocin, but unlike these drugs, AL-34662 was designed specifically as a peripherally selective drug, which does not cross the blood–brain barrier. This means that AL-34662 can exploit a useful side effect of the hallucinogenic 5-HT2A agonists, namely reduction in intra-ocular pressure and hence relief from the symptoms of glaucoma, but without causing the hallucinogenic effects that make centrally active 5-HT2A agonists unsuitable for clinical use. In animal studies, AL-34662 has been shown to be potent and effective in the treatment of symptoms of glaucoma, with minimal side effects.