Clozapine Is Severely Underused in Parkinson's Disease Patients

Brief commentary: Under-recognition of underuse of clozapine in treating psychotic symptoms in Parkinson's disease

Clozapine is an important drug in the treatment of Parkinson's disease (PD). It has proven efficacy in treating PD psychosis without worsening motor function, as well as in treating tremor refractory to L-Dopa, yet it is severely underused in the United States. Unlike the situation of treatment resistant schizophrenia, this underuse is underrecognized.

On the Optimal Diagnosis and the Evolving Role of Pimavanserin in Parkinson's Disease Psychosis

Parkinson's disease (PD) is associated with the development of psychosis (PDP), including hallucinations and delusions, in more than half of the patient population. Optimal PD management must therefore involve considerations about both motor and non-motor symptoms. Often, clinicians fail to diagnosis psychosis in patients with PD and, when it is recognized, treat it suboptimally, despite the availability of multiple interventions. In this paper, we provide a summary of the current guidelines and clinical evidence for treating PDP with antipsychotics. We also provide recommendations for diagnosis and follow-up. Finally, an updated treatment algorithm for PDP that incorporates the use of pimavanserin, the only US FDA-approved drug for the treatment of PDP, was developed by extrapolating from a limited evidence base to bridge to clinical practice using expert opinion and experience. Because pimavanserin is only approved for the treatment of PDP in the US, in other parts of the world other recommendations and algorithms must be considered.

Second-generation antipsychotics for Parkinson's disease psychosis: A systematic review and network meta-analysis

OBJECTIVE

This network meta-analysis assessed the efficacy, tolerability, and acceptability of second-generation antipsychotics (SGAs) for Parkinson's disease psychosis (PDP).

METHODS

We searched PubMed, Embase, Cochrane Library, and ClinicalTrials.gov for randomized controlled trials investigating SGAs for PDP up to October 26, 2023.

RESULTS

We included 16 trials (N = 1252) investigating clozapine, melperone, olanzapine, pimavanserin, quetiapine, ulotaront, and placebo. In comparisons between SGAs and placebo, the findings were: i) Standardized mean differences, 95% confidence intervals (SMDs, 95%CIs), for psychotic-symptom reduction revealed the first rank of clozapine (-1.31, -1.73 to -0.89), the second rank of pimavanserin, with significant inferiority of quetiapine (SMD = 0.47, 0.02 to 0.92); ii) Mean differences (MDs, 95%CIs) for abnormal movement, as assessed by the Unified Parkinson's Disease Rating Scale - Part III, indicated that clozapine had the least motor side effects (-0.92, -2.75 to 0.91); iii) Risk ratios (RRs, 95% CIs) for adverse-effect dropout rates were lowest for melperone (1.02, 0.20 to 5.24); and iv) RRs (95% CIs) for all-cause dropout rates were lowest for clozapine (0.73, 0.42 to 1.25).

CONCLUSIONS

For patients with PDP, clozapine may substantially reduce psychotic symptoms with minimal abnormal movement, high acceptability, and moderate overall tolerability. Pimavanserin, not quetiapine, could be an alternative.

Parkinson's disease psychosis management: an evidence based, experience informed, pragmatic approach

INTRODUCTION

Psychotic symptoms in people with Parkinson's disease (PD) have attracted increasing. Recommendations on treating psychosis often fail to take into account what psychotic symptoms require treatment, which has been complicated by the increasing number of reports documenting the frequency of 'minor' hallucinations.

AREAS COVERED

This article focuses both on the phenomenology of psychotic symptoms and their management.

EXPERT OPINION

Understanding the nature and implications of the types of psychotic symptoms in PD is the key to proper treatment. Evidence and experience-based data on the effect of anti-psychotic medications will be reviewed and how the various clinical settings should determine the treatment approach. The evidence base consists of all reported blinded trials recorded in PubMed and the experience-based studies are those chosen by the author from PubMed as illustrative. Specific recommendations for the treatment of psychosis will be listed for specific situations. Pimavanserin is the first-line choice for mild symptoms; quetiapine for symptoms that require improvement in a short period and clozapine for urgent problems or those which fail the other approaches.

Rethinking Clozapine: Lights and Shadows of a Revolutionary Drug

The current literature globally highlights the efficacy of Clozapine in several psychiatric disorders all over the world, with an FDA indication for reducing the risk of repeated suicidal behavior in patients with schizophrenia or schizoaffective disorder. A growing field of research is also stressing a possible broader beneficial effect of Clozapine in promoting neuroprotection and neurotrophism. However, this drug is linked to several life-threatening side effects, such as agranulocytosis, myocarditis and seizures, that limit its use in daily clinical practice. For this work, a search was performed on PubMed using the terms "Clozapine indications", "Clozapine adverse effects", "Clozapine regenerative effects", and "Clozapine neuroplasticity" with the aim of reviewing the scientific literature on Clozapine's treatment indications, adverse effects and potential regenerative role. The results confirmed the efficacy of clozapine in clinical practice, although limited by its adverse effects. It appears crucial to raise awareness among clinicians about the potential benefits of using Clozapine, as well educating medical personnel about its risks and the early identification of possible adverse effects and their management.

Clozapine: Efficacy for Parkinson Disease psychosis in patients refractory to pimavanserin

Pimavanserin is the only approved drug for Parkinson's disease psychosis (PDP) and is an increasingly used therapy where available. Clozapine has proven efficacy for PDP but is much less commonly used secondary to frequent blood tests to monitor for agranulocytopenia. We identified 27 patients with PDP (72 ± 7.3 years, 11 (41%) female), with an inadequate response to pimavanserin, who subsequently started clozapine. The final mean daily dose of clozapine was 49.5 mg [range 25-100] at night, and mean duration of follow-up was 17 months [range: 2-50 months]. Patients reported clozapine to be markedly effective in 11 (41%), moderately effective in 6 (22%), somewhat effective in 5 (18%). No patient reported that it was ineffective, but 5 (19%) had inadequate follow-up. Clozapine should be considered in pimavanserin refractory psychosis.