BRL 54443 (MALEATE) is a potent agonist for the 5-HT1E/1F receptors, exhibiting Ki values of 1.1 nM and 0.7 nM, respectively. It is over 30 times more selective in its affinity for these receptors than for other serotonin (5-HT) and dopamine receptors.

BRL54443 exhibits high affinity for 5-HT 1F receptors, despite its lower affinity for a range of other receptors, including 5-HT 1A (63 nM), 5-HT 1B (126 nM), 5-HT 1D (63 nM), 5-HT 2A (1259 nM), 5-HT 2B (100 nM), 5-HT 2C (316 nM), 5-HT 6 (>10,000 nM), 5-HT 7 (>10,000 nM), D 2 (501 nM), D 3 (631 nM), and α 1B -adrenoceptors (1259 nM). In DG membranes, this compound selectively stimulates 5-HT 1E receptors and efficiently inhibits forskolin-dependent cAMP production with an IC 50 value of 14 nM. Additionally, BRL 54443 (MALEATE) (MALEATE) induces contraction with a -log EC 50 value of 6.52.

Peripheral administration of BRL54443 (5-HT(1E/1F); 3-300 microg/paw) on the ipsilateral side significantly diminished the incidence of flinching caused by formalin in rats, indicating antinociceptive effects. However, this reduction was not observed with contralateral administration.