A double-blind trial of adjunctive allopurinol for schizophrenia.

Objective: To investigate if adjunctive allopurinol reduces symptoms in schizophrenia outpatients with persistent symptoms despite adequate pharmacotherapy.

Method: N=59 schizophrenia outpatients were randomly assigned to receive adjunctive allopurinol 300 mg bid or identical-looking placebo for 8 weeks after a 2-week placebo run-in. Symptoms were assessed biweekly.

Results: A total of n=51 patients completed the trial. Including all n=59 randomized patients, a total of 4 of 31 in the allopurinol group and 0 of 28 in the placebo group had at least a 20% reduction in total PANSS score at the final study visit (chi-square=3.88, p=.049). Among the n=51 completers, individuals in the allopurinol group rated themselves as more improved than did those in the placebo group (z=-2.24, p=.025). The allopurinol medication was well tolerated and there were not any adverse events attributed to the study medication.

Conclusions: Allopurinol may be an effective adjunctive medication for some patients with persistent schizophrenia.