5-HT4 antagonist 1 is an antagonist of 5-HT4 (pKi = 9.6).

6-Hydroxy Buspirone, an active metabolite of the anxiolytic compound buspirone, is produced via the cytochrome P450 (CYP) isoform CYP3A4. This compound exhibits affinity for the serotonin (5-HT) receptor subtype 5-HT1A, demonstrating efficacy in the rat hippocampus and dorsal raphe with half-maximal effective concentrations (EC50s) of 4 and 1 µM, respectively. Furthermore, 6-Hydroxy Buspirone acts as a potent antagonist against dopamine D2, D3, and D4 receptors with half-maximal inhibitory concentrations (IC50s) of 3.1, 4.9, and 0.85 µM, respectively, and inhibits the organic cation transporters 1 (OCT1), OCT2, and OCT3 in S2 proximal tubule cells expressing human transporters, showcasing a concentration-dependent mechanism.

Eltoprazine(DU28853) is a serenic or antiaggressive agent which as an agonist at the 5-HT1A and 5-HT1B receptors and as an antagonist at the 5-HT2C receptor.IC50 value:Target: 5-HT1A/1B agonist; 5-HT2C antagonistin vitro: The binding of [3H]eltoprazine to whole tissue sections was saturable and revealed an apparent dissociation constant (Kd) of 11 nM. Specific [3H]eltoprazine binding was completely displaced by 5-HT; conversely, unlabelled eltoprazine reduced [3H]5-HT binding to the levels of non-specific binding [1]. Eltoprazine evoked membrane changes that were similar to but much weaker than those induced by 5HT. Both the 5HT- and eltoprazine-evoked membrane hyperpolarizations were largely suppressed in the presence of spiperone [2].in vivo: eltoprazine is extremely effective in suppressing dyskinesia in experimental models, although this effect was accompanied by a partial worsening of the therapeutic effect of l-dopa. Interestingly, eltoprazine was found to (synergistically) potentiate the antidyskinetic effect of amantadine. The current data indicated that eltoprazine is highly effective in counteracting dyskinesia in preclinical models [3]. Rats were chronically treated with mianserin (10 mg/kg i.p.) or eltoprazine (1 mg/kg i.p.) and were tested in the elevated plus-maze test for anxiety. Mianserin and eltoprazine displayed opposite effects in the elevated plus-maze: mianserin induced anxiolytic-like effects, while eltoprazine showed anxiogenic-like ones [4]. [1]. Sijbesma H, et al. Eltoprazine, a drug which reduces aggressive behaviour, binds selectively to 5-HT1 receptor sites in the rat brain: an autoradiographic study. Eur J Pharmacol. 1990 Feb 20;177(1-2):55-66. [2]. Joels M, et al. Eltoprazine suppresses hyperpolarizing responses to serotonin in rat hippocampus. J Pharmacol Exp Ther. 1990 Apr;253(1):284-9. [3]. Bezard E, et al. Study of the antidyskinetic effect of eltoprazine in animal models of levodopa-induced dyskinesia. Mov Disord. 2013 Jul;28(8):1088-96. [4]. Rocha B, et al. Chronic mianserin or eltoprazine treatment in rats: effects on the elevated plus-maze test and on limbic 5-HT2C receptor levels. Eur J Pharmacol. 1994 Sep 1;262(1-2):125-31.

Loxapine hydrochloride is a dibenzoxazepine anti-psychotic agent that exerts its effects through oral administration, functioning as an inhibitor of dopamine and an antagonist of 5-HT receptors [1] [4].