Delayed appearance of facial tics following chronic fluphenazine administration to guinea pigs.

Guinea pigs were administered chronic fluphenazine decanoate for 11 months and oral movements (OMs) were periodically observed using several different paradigms. Shortly after the initiation of neuroleptic treatment, increased OMs were seen in the drugged animals, but these did not persist and may have reflected a decreased fear (freezing) reaction in the tranquilized animals, being correlated with increased locomotion in open field. After 7 months of neuroleptics, twitch-like movements of the orofacial region were observed in the drugged animals; these dyskinetic movements were enhanced by administration of d-amphetamine. These twitch-like movements appear to be a better model of tardive dyskinesia in the guinea pig than the initially observed and normal-appearing OMs.