This study was conducted to determine whether the addition of naltrexo
ne to ongoing neuroleptic treatment would facilitate the reduction in
positive or negative symptoms in patients with schizophrenia. Twenty-o
ne patients meeting DSM-III criteria for schizophrenia were enrolled;
all patients had been stabilized for at least 2 weeks on their dosage
of neuroleptic medicine before entering the study. Patients were rando
mized to receive either placebo or naltrexone 200 mg/day for 3 weeks i
n addition to their neuroleptic. Patients randomized initially into th
e placebo arm were crossed over to receive naltrexone in a single-blin
d fashion for 3 additional weeks. All patients were rated weekly with
the Brief Psychiatric Rating Scale (BPRS). Fifteen patients received p
lacebo and six received naltrexone in the first 3 weeks. No significan
t effects of naltrexone on total BPRS scores or BPRS subscale scores w
ere observed. Patients who received naltrexone on a single-blind basis
at the end of the placebo-controlled trial demonstrated a transient e
xacerbation in negative symptoms as reflected by the total BPRS score
and the BPRS Withdrawal-Retardation subscale score. Repeated-measures
analysis of variance (ANOVA) on the BPRS total Score of the subsequent
treatment with naltrexone showed a trend for a significance in the dr
ug by time effect. Repeated-measures ANOVA on the BPRS Withdrawal-Reta
rdation subscale of the subsequent treatment with naltrexone showed a
significant drug by time effect. The current data failed to indicate a
clinical benefit when naltrexone was added to the neuroleptic regimen
. Other potential applications of naltrexone in schizophrenia are addr
essed.