Catalepsy was induced in Male Sprague-Dawley rats by intraperitoneal injection of 1 ml kg−1 Haloperidol dissolved with an equal weight of tartaric acid. Rats were tested for catalepsy by positioning them such that their hindquarters rested on the bench while their forelimbs rested on a 1 cm diameter horizontal bar, 10 cm above the bench. The time that the rats maintained this position was recorded up to 120 seconds maximum. Rats were labeled cataplexic if they maintained the position for more than 30 seconds. The test was repeated 30, 60 and 90 min after drug administration. SB-228357 significantly attenuated haloperidol-induced catalepsy when dosed orally at 0.32–10 mg/kg by dissolving in one drop of BRIJ-35 and diluting in 1% methylcellulose (final delivery volume of 2 ml/kg).

Radioligand binding assays were carried out with homogenates of human recombinant 5-HT2A, 5-HT2B, and 5-HT2C receptors expressed in Human Embryo Kidney (HEK293) cells. Cells were incubated with 0.01 nM – 0.01 mM SB-22837 for 30–45 min along with 0.5 nm [3H]-ketanserin (5-HT2A), 8 nm [3H]-5-HT (5-HT2B) or 0.6 nm [3H]-mesulergine (5-HT2C). SB-22837 exhibited the following pKi binding profiles: 5-HT2A pKi = 6.97; 5-HT2B pKi = 8.14; and 5-HT2C pKi = 9.14.