Dependence-producing properties of alprazolam in the dog.

Alprazolam (48 mg/kg/day) administered orally to dogs 4 times a day in equally divided doses produced physical dependence. This dependence was revealed by a precipitated abstinence syndrome which occurred after either oral administration of flumazenil (6, 18 and 36 mg/kg) or intravenous administration of a liposomal suspension of flumazenil. Flumazenil alone (18, 36 and 72 mg/kg) produced no significant signs of precipitated abstinence in naive dogs. This precipitated abstinence syndrome in alprazolam-dependent dogs was characterized by both clonic and tonic-clonic seizures. Other signs of precipitated abstinence which comprise the NPAS score were less intense in the alprazolam-dependent than in diazepam-dependent dogs. Alprazolam is extensively metabolized in the dog and does not accumulate whereas its predominant metabolite, alpha hydroxyalprazolam, does accumulate. The data suggest that alpha hydroxyalprazolam plays a role in the dependence-producing properties of alprazolam in the dog as revealed by the precipitated abstinence syndrome.