A double-blind trial of adjunctive allopurinol for schizophrenia

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

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.

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.

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