Efficacy and Safety of Zonisamide in Dementia with Lewy Bodies Patients with Parkinsonism: A Post Hoc Analysis of Two Randomized, Double-Blind, Placebo-Controlled Trials

An Update on Nondopaminergic Treatments for Motor and Non-motor Symptoms of Parkinson's Disease

Nondopaminergic neurotransmitters such as adenosine, norepinephrine, serotonin, glutamate, and acetylcholine are all involved in Parkinson's disease (PD) and promote its symptoms. Therefore, nondopaminergic receptors are key targets for developing novel preparations for the management of motor and non-motor symptoms in PD, without the potential adverse events of dopamine replacement therapy. We reviewed English-written articles and ongoing clinical trials of nondopaminergic treatments for PD patients till 2014 to summarize the recent findings on nondopaminergic preparations for the treatment of PD patients. The most promising research area of nondopaminergic targets is to reduce motor complications caused by traditional dopamine replacement therapy, including motor fluctuations and levodopa-induced dyskinesia. Istradefylline, Safinamide, and Zonisamide were licensed for the management of motor fluctuations in PD patients, while novel serotonergic and glutamatergic agents to improve motor fluctuations are still under research. Sustained- release agents of Amantadine were approved for treating levodopa induced dyskinesia (LID), and serotonin 5HT1B receptor agonist also showed clinical benefits to LID. Nondopaminergic targets were also being explored for the treatment of non-motor symptoms of PD. Pimavanserin was approved globally for the management of hallucinations and delusions related to PD psychosis. Istradefylline revealed beneficial effect on daytime sleepiness, apathy, depression, and lower urinary tract symptoms in PD subjects. Droxidopa may benefit orthostatic hypotension in PD patients. Safinamide and Zonisamide also showed clinical efficacy on certain non-motor symptoms of PD patients. Nondopaminergic drugs are not expected to replace dopaminergic strategies, but further development of these drugs may lead to new approaches with positive clinical implications.

Efficacy of Adjunctive Therapy with Zonisamide Versus Increased Dose of Levodopa for Motor Symptoms in Patients with Dementia with Lewy Bodies: The Randomized, Controlled, Non-Inferiority DUEL Study

BACKGROUND

In patients with dementia with Lewy bodies (DLB), it is unknown whether adjunct zonisamide is as effective and safe as increasing levodopa dose when levodopa has inadequate efficacy on parkinsonism.

OBJECTIVE

To compare adjunct zonisamide 25 mg/day versus an increased levodopa dose (increased by 100 mg/day) in patients with DLB treated with levodopa ≤300 mg/day for parkinsonism.

METHODS

The DUEL study was a multicenter, randomized, controlled, open-label, parallel-group, interventional, non-inferiority trial. During the observation period, levodopa was administered at ≤300 mg/day for 4 weeks. Subsequently, patients were randomized to receive adjunct zonisamide 25 mg/day or levodopa increased by 100 mg/day.

RESULTS

Respective adjusted mean changes in MDS-UPDRS Part III total score at 16 and 24 weeks (primary endpoint) were -6.3 and -4.4 in the zonisamide add-on and -0.8 and 2.0 in the levodopa increase groups. The adjusted mean difference at 24 weeks was -6.4 (95% confidence interval [CI] -13.5, 0.7); the upper limit of the 95% CI (0.7) was lower than the non-inferiority margin (3.0). No significant between-group differences were observed in total scores of the MDS-UPDRS Part II, Eating Questionnaire, EuroQol-5 dimension-5 level, Zarit Caregiver Burden Interview, or other secondary endpoints. No notable between-group differences were observed in adverse event incidences.

CONCLUSION

Adjunct zonisamide 25 mg/day may yield moderate improvement in motor symptoms in patients with DLB when the levodopa effect is insufficient, but it could not be verified that the zonisamide 25 mg/day was as effective as levodopa 100 mg/day because levodopa showed no sufficient efficacy as assumed.

Recent advances in Lewy body dementia: A comprehensive review

Lewy Body Dementia is the second most frequent neurodegenerative illness proven to cause dementia, after Alzheimer's disease (AD). It is believed to be vastly underdiagnosed, as there is a significant disparity between the number of cases diagnosed clinically and those diagnosed via neuropathology at the time of postmortem autopsy. Strikingly, many of the pharmacologic treatments used to treat behavioral and cognitive symptoms in other forms of dementia exacerbate the symptoms of DLB. Therefore, it is critical to accurately diagnose DLB as these patients require a specific treatment approach. This article focuses on its pathophysiology, risk factors, differentials, and its diverse treatment modalities. In this study, an English language literature search was conducted on Medline, Cochrane, Embase, and Google Scholar till April 2022. The following search strings and Medical Subject Headings (MeSH) terms were used: "Lewy Body Dementia," "Dementia with Lewy bodies," and "Parkinson's Disease Dementia." We explored the literature on Lewy Body Dementia for its epidemiology, pathophysiology, the role of various genes and how they bring about the disease, biomarkers, its differential diagnoses and treatment options.

Zonisamide improves axial symptoms in dementia with Lewy bodies with parkinsonism: Post hoc analysis of clinical trials

Patients with dementia with Lewy bodies (DLB) experience worsening axial symptoms with disease progression, which can negatively affect quality of life. Previous phase 2 and 3 clinical trials conducted in Japan showed that zonisamide improved parkinsonism in patients with DLB. In the present study, we performed a post hoc analysis of pooled data from the previous phase 2 and 3 trials to examine the effect of zonisamide on axial symptoms in this patient group. In our pooled analysis, the primary outcome was the change from baseline to 12 weeks in axial symptom score, measured as the sum of Unified Parkinson's Disease Rating Scale Part III items relevant to gait/balance/midline function. A total of 498 patients were included in this analysis. Zonisamide 25 mg and 50 mg significantly reduced the axial symptom score at week 12 compared with placebo (p < 0.01 and p < 0.001, respectively, by mixed model of repeated measures). Our findings indicate that zonisamide may improve axial symptoms in DLB with parkinsonism and, thus, may potentially reduce the risk of falls and improve quality of life in this vulnerable patient population.

The Application of Zonisamide to Patients Suffering from Dementia with Lewy Bodies: Emerging Clinical Data

Zonisamide is an anti-epileptic medication with multiple mechanisms of action and a favorable safety profile. Zonisamide may interact with Lewy body dementia pathophysiology through a mechanism unrelated to its original indication. Zonisamide has shown efficacy as adjunct therapy for the management of motor symptoms in patients with Parkinson's disease (PD). Given that dementia with Lewy bodies (DLB) and PD are considered subtypes of a Lewy body disease spectrum, zonisamide was investigated for the treatment of parkinsonism in DLB. Phase II and phase III clinical trials were conducted in patients with DLB in Japan. In both studies, participants were randomized to receive 12 weeks of zonisamide 25 or 50 mg/day or placebo. Zonisamide significantly improved the Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) without affecting the Mini-Mental State Examination (MMSE) or Neuropsychiatry Inventory-10 (NPI-10) scores at week 12. In 2018, zonisamide received Japanese regulatory approval for the additional indication of parkinsonism in DLB. This review discusses the emerging clinical data on zonisamide in the field of DLB.