Combination Therapy of Long-Acting Injectable Second-Generation Antipsychotics and Oral Antipsychotics: A Retrospective Chart Review and Prescribers' Attitude Survey

Background Although long-acting injectable antipsychotics (LAI-APs) have been considered as a monotherapeutic option in the maintenance treatment of schizophrenia, it has been recently reported that the combination therapy of LAI-APs and oral antipsychotics (OAPs) is common. Methods We conducted a retrospective chart review to examine the situation of the combination therapy of LAI second-generation antipsychotics (LAI-SGAs) and OAPs, and a questionnaire survey to investigate prescribers' attitudes toward the combination therapy. We included patients who received any LAI-SGAs for 1 month or longer and classified them into monotherapy and combination therapy groups. We collected information on age, sex, primary psychiatric diagnosis, and concomitant psychotropic medications. Results Of the 132 patients, 39 (29.5%) received the combination therapy of LAI-SGAs and OAPs. Long-acting injectable risperidone was significantly associated with receiving the combination therapy compared with LAI aripiprazole. Olanzapine was the most common OAP in combination with LAI-SGAs. Only 8 patients (20.5%) concurrently received the same type of OAPs as LAI-SGAs. More than 60% of the patients received OAP polypharmacy before the initiation of LAI-SGAs. The psychiatrists in charge prescribed LAI-SGAs mainly because of a concern about adherence, and OAPs mainly because of insufficient dose of LAI-SGAs, to patients in the combination therapy group. They estimated that adherence to OAPs in two thirds of the patients in the combination therapy group was 80% or higher. Conclusions The present study showed that the combination therapy of LAI-SGAs and OAPs is often conducted in real-world clinical practice. Considering the reason for the introduction of LAI-APs, clinicians should carefully monitor patients' adherence to OAPs concurrently used with LAI-APs.