I In rats, Pimavanserin (3 mg/kg, p.o.) attenuates DOI-induced head twitches. In mice, Pimavanserin (3 mg/kg, p.o.) significantly attenuated MK-801-induced hyperactivity. In a rat model of Parkinsonian tremor, Pimavanserin (40 mg/kg, I. p.) comprehensively attenuated tacrine-induced paw tremor.