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.