Pathological gambling (PG) is a potential complication related to the treatment 
of Parkinson disease (PD) with dopamine agonists (DA). The cause of this 
disorder is unknown, but altered dopamine neurotransmission may be involved.
OBJECTIVE: We evaluated the efficacy and tolerability of the opioid antagonist 
naltrexone in the treatment of PG in PD.
METHODS: Our cases included 3 patients with PD who developed PG after DA 
treatment.
RESULTS: Pathological gambling did not improve after reduction or 
discontinuation of DA. These patients responded poorly to serotonin reuptake 
inhibitors, whereas treatment with opioid antagonist naltrexone resulted in the 
remission of PG. Naltrexone treatment was well tolerated. In one patient, higher 
dose of naltrexone resulted in hepatic abnormalities, which resolved after 
dosage reduction.
CONCLUSIONS: The opioid antagonist naltrexone could be an effective option for 
the treatment of PG in PD.