B-HT 920, A DOPAMINE-D2 AGONIST, IN THE TREATMENT OF NEGATIVE SYMPTOMS OF CHRONIC-SCHIZOPHRENIA

A prospective, nonblind 8-week trial of talipexole dihydrochloride (B- HT 920), a dopamine D2 agonist, was conducted in 15 schizophrenic pati ents with predominantly negative symptoms. B-HT 920 was initiated at 0 .15 mg/day and then adjusted at 0.15-2.4 mg/day on the basis of clinic al response and side effects. Dosage of concurrent neuroleptics was fi xed at least 3 weeks prior to the trial and was unchanged throughout t he study period. In addition to clinical assessment, levels of plasma homovanillic acid (pHVA), a potential index of central dopamine turnov er, were measured. There was a small but significant (p < 0.01, Wilcox on test) reduction in total scores of the Scale for the Assessment of Negative Symptoms or in a cluster score o three negative items (Emotio nal Withdrawal, Blunted Affect, and Psychomotor Retardation) of the Br ief Psychiatric Rating Scale (BPRS). No change was observed in cluster scores of positive items of BPRS. There was a weak negative correlati on between pHVA levels and the cluster scores of negative items of BPR S both at weeks 0 and 8 of the trial. The clinical results suggest tha t activation of D2 receptors was related to partial amelioration of th e negative symptoms. The clinical and biochemical findings are consist ent with a hypothesis that decreased dopaminergic activity may be rela ted to the etiology of negative symptoms of schizophrenia.