SB-258741 behaves as a partial inverse agonist, the antagonist potency (apparent pK B ) is 8.47 [2].

SB 258741 (0-9.1 mg/kg; s.c.; once or daily for 3 days) shows antipsychotic effects in rats [1]. Animal Model: Male Wistar rats, 250 –300 g in the phencyclidine (PCP)-disrupted prepulse inhibition (PPI) and PCP-disrupted social interaction (SIT) paradigm, 200 – 250 g in the catalepsy, motility, and D-amphetamine hyperactivity paradigms [1] Dosage: 0.56, 2.3, 4.6 and 9.1 mg/kg Administration: Subcutaneous injection, once or daily for 3 days (social interaction test) Result: Reversed hyperactivity induced by D-amphet-amine over 0.56 mg/kg, and reduced motility at 4.6 and 9.1 mg/kg. Did not reverse D-Amphetamine-disrupted PPI, but enhanced PCP-disrupted PPI. Reduced PCP (2 mg/kg)-induced hyperactivity.