Overcoming antipsychotic-induced parkinsonism: efficacy of monthly long-acting risperidone in a complex schizophrenia case

Introduction

Antipsychotic-induced parkinsonism is a clinically significant adverse effect that may substantially limit pharmacological options in the treatment of schizophrenia and negatively impact long-term adherence and functional outcomes. This is particularly challenging in patients who exhibit intolerance to multiple antipsychotic agents, including both oral and long-acting injectable formulations. In such cases, therapeutic strategies must carefully balance efficacy, tolerability, and adherence support, often requiring complex and highly individualized clinical approaches.

Aims

This case report aims to describe the clinical course and therapeutic strategy in a patient with chronic schizophrenia and a history of antipsychotic-induced parkinsonism, emphasizing the role, efficacy, and tolerability of monthly long-acting injectable risperidone as adjunctive therapy to clozapine in a clinically complex context.

Methods

We present a single-case descriptive report of a 53-year-old male with a 30-year history of schizophrenia followed in psychiatric care. Clinical data were obtained through longitudinal assessment during outpatient follow-up and inpatient admission, supported by review of clinical records and direct clinical observation. Given the nature of the report, no statistical analyses were performed. Clinical outcomes were evaluated based on symptom evolution, adverse effect profile, treatment adherence, need for hospitalization, and overall functional stabilization over time.

Results

The patient had previously developed significant drug-induced parkinsonism during treatment with paliperidone long-acting injectable, which led to its discontinuation. In addition, prior exposure to aripiprazole had been complicated by priapism, further restricting pharmacological options and limiting future therapeutic choices. Following discontinuation of long-acting injectable antipsychotics, clozapine monotherapy was initiated, resulting in good initial clinical stabilization, with adequate control of psychotic symptoms and partial recovery of psychosocial functioning. However, treatment could not be titrated beyond 150 mg/day due to dose-limiting adverse effects, including marked sialorrhea, constipation, and daytime sedation, which negatively impacted tolerability and long-term adherence. Despite early stability under clozapine, the patient subsequently developed treatment non-adherence, leading to progressive clinical deterioration, functional decline, and ultimately requiring involuntary psychiatric admission due to relapse of psychotic symptoms with behavioural disorganization and impaired insight. During hospitalization, clozapine was reintroduced and maintained at 150 mg/day; however, further dose escalation remained unfeasible due to persistence of the same adverse effects. Given the combination of partial therapeutic response, adherence difficulties, and ongoing clinical vulnerability, monthly long-acting injectable risperidone was introduced as adjunctive therapy to ensure sustained antipsychotic coverage. The combination of clozapine and monthly long-acting injectable risperidone resulted in complete remission of psychotic symptoms. Importantly, no recurrence of extrapyramidal symptoms, including parkinsonism, was observed throughout follow-up. The treatment was well tolerated overall, without emergence of new significant adverse effects. The patient achieved sustained clinical stabilization, improved adherence, and was discharged under combined maintenance therapy.

Conclusions

This case illustrates that monthly long-acting injectable risperidone may be a safe and effective adjunct to clozapine in selected patients with schizophrenia, even in the context of previous antipsychotic-induced parkinsonism. Carefully individualized combination strategies may enhance adherence, improve symptom control, and maintain clinical stability while minimizing extrapyramidal risk in complex, treatment-refractory cases.

References

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