Adding another antipsychotic to a treatment regimen was previously used in evaluating the medication's efficacy. Supplementation of depot antipsychotics with oral antipsychotics is particularly meaningful because depot formulations are typically chosen for patients struggling with adherence to oral antipsychotics. This post-hoc analysis assessed supplementation of olanzapine long-acting injection (olanzapine-LAI) with oral olanzapine.

We used 12 months of data from an open-label, single-arm extension study of patients with schizophrenia or schizoaffective disorder (N = 931) treated with olanzapine-LAI. The prevalence, duration, time to first supplementation, and best predictors of oral supplementation were assessed.

Oral supplementation occurred in 21% of patients for a median of 31 days with mean modal dose of 10.8 mg/day. Mean time to first supplementation was shorter for patients who were at least moderately ill at baseline compared to less ill patients (47 vs. 97 days, p < 0.001). Best predictors of oral supplementation included a more severe illness profile at baseline, lower olanzapine-LAI dose prior to oral supplementation, supervised living arrangements, and being African-American.

Supplementation of olanzapine-LAI appears to be infrequent, of relatively short duration, and reserved for more severely ill patients who may require a targeted rescue medication due to signs of impending relapse.