The Impact of Antipsychotic Formulations on Time to Medication Discontinuation in Patients with Schizophrenia: A Dutch Registry-Based Retrospective Cohort Study

Background: Many patients with schizophrenia discontinue antipsychotic medication, frequently with adverse outcomes. Although different antipsychotic formulations are associated with different times to discontinuation, not much is known about discontinuation rates with oral-weekly formulations. Such a formulation of penfluridol is available in both the Netherlands and several other countries. Objectives: We aimed to investigate the impact of antipsychotic formulations on time to discontinuation, especially the oral-weekly formulation. Methods: In a large, registry-based, retrospective cohort study from 1 January 2013 to 31 December 2016, we determined the time to medication discontinuation during the follow-up period with antipsychotic formulations, including oral-daily, oral-weekly, depot, or a combination of these. Patients with schizophrenia aged between 18 and 69 years were included and stratified according to the duration of recent antipsychotic use (taking the same formulation for ≤ 60 days or > 60 days before follow-up: short-term or long-term recent antipsychotic use). Medication discontinuation was defined as discontinuation of current antipsychotic formulation. Results: Overall, 8257 patients were included for analyses, with 80% of patients discontinuing antipsychotic medication. Time to discontinuation was longer in those with long-term recent antipsychotic use before the follow-up period and longest for oral-daily formulations. Patterns for discontinuation of oral-weekly and depot formulations were similar, regardless of the duration of recent antipsychotic use before follow-up. More prior discontinuations were associated with shorter time to discontinuation. Conclusions: Time to discontinuation differed considerably between formulations. The duration of recent antipsychotic use was a strong predictor of time to discontinuation. While oral-daily formulations had the longest time to discontinuation in the long-term recent antipsychotic use group, discontinuation trends were similar for oral-weekly and depot formulations. An oral-weekly formulation, whose administration route is noninvasive, might therefore be considered an alternative to depot formulations.