Risperidone long-acting in-situ microimplant in the acute management of manic episodes with psychotic symptoms in non-adherent patients with schizoaffective disorder: a retrospective real-world study

Background : Nonadherence is a major cause of relapse in patients with schizophrenia, schizoaffective disorder, or bipolar disorder who have achieved remission. However, it is also a significant challenge during manic episodes. Risperidone in-situ microimplant (ISM) releases the drug early and in a sustained manner once a month, eliminating the need for daily administration, which can be difficult during a manic episode. In this study, we examined the short-term efficacy and tolerability of risperidone ISM in real-world nonadherent inpatients with schizoaffective disorder experiencing a manic episode with psychotic symptoms. Methods : This retrospective, observational, single-centre study included 50 consecutive adults admitted after discontinuation/marked non-adherence and with prior response to risperidone received ≥6 days of oral risperidone to confirm tolerability, then risperidone ISM (75 or 100 mg) and were followed for 6 weeks. Mania severity was assessed with the Young Mania Rating Scale (YMRS). Results : Fifty patients were included; most received concomitant mood stabilisers and benzodiazepines. Median YMRS decreased from 32 at admission to 26 at first injection (after the oral lead-in), 8 by day 8, and remained low at day 28 (5) and day 42 (6). Activation/behavioural items improved earlier, whereas psychotic thought content improved more gradually, predominantly between days 8 and 28. Side-effect burden at weeks 4 and 6 was minimal, and no discontinuations due to adverse events occurred. Conclusions : In this exploratory uncontrolled cohort, oral risperidone lead-in plus monthly risperidone ISM within multimodal inpatient care was associated with rapid and sustained improvement and favourable short-term tolerability. These findings should be interpreted as resulting from a combination of ISM treatment and a structured inpatient strategy, rather than as evidence of the effect of ISM alone. Prospective, controlled studies are warranted.