# APBA Kısa Özet

A systematic review of three RCTs (n=560) found that extended-release IPX203 increased total "Good On-time" and reduced "Off-time" compared to immediate-release carbidopa-levodopa in advanced Parkinson's disease. Motor function (Part III UPDRS) improved more with IPX203. Adverse event incidence was comparable, but treatment-emergent adverse events and discontinuations were more frequent with IPX203.

# Çalışma neyi araştırdı?

This systematic review aimed to evaluate the efficacy and safety of IPX203, a newly approved oral carbidopa-levodopa formulation designed to prolong the therapeutic effect, compared to the standard immediate-release formulation in patients with advanced Parkinson's disease. The review followed PRISMA guidelines and was registered in the International Prospective Register of Systematic Reviews (registration number: CRD42024623230). A comprehensive search of PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, ScienceDirect, Scopus, and Embase identified randomized controlled trials comparing IPX203 with immediate-release carbidopa-levodopa. The primary outcomes were changes from baseline in "Good On-time" (periods of effective symptom control with minimal dyskinesia) and "Off-time." Secondary outcomes included motor function assessments using Part III of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and safety outcomes, specifically adverse event incidence and treatment discontinuations. Data were synthesized qualitatively due to heterogeneity in study populations and designs.

# Yöntem

The review included three randomized controlled trials with a total sample size of 560 participants. Studies were selected based on predefined criteria comparing IPX203 to immediate-release carbidopa-levodopa. Primary outcomes focused on changes from baseline in "Good On-time" and "Off-time." Secondary outcomes included motor function assessments using Part III of the MDS-UPDRS and safety outcomes, specifically adverse event incidence and treatment discontinuations. Data were synthesized qualitatively due to heterogeneity in study populations and designs. The search strategy encompassed major databases such as PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, ScienceDirect, Scopus, and Embase to ensure comprehensive coverage of available evidence. Inclusion criteria specified randomized controlled trials involving patients with advanced Parkinson's disease comparing IPX203 against immediate-release carbidopa-levodopa.

# Temel bulgular

  • Good On-time: IPX203 significantly increased total "Good On-time" compared to immediate-release carbidopa-levodopa. The extension of "Good On-time" represents a critical advancement for patients experiencing motor fluctuations, as it directly correlates with periods of effective symptom control and minimal dyskinesia.
  • Off-time: IPX203 reduced "Off-time" compared to the immediate-release formulation. Reduction in "Off-time" is a primary therapeutic goal in advanced Parkinson's disease, as it reflects periods of improved mobility and symptom control.
  • Motor Function: Scores on Part III of the MDS-UPDRS demonstrated greater improvement in motor function with IPX203. Improvement in Part III UPDRS scores indicates better control of motor symptoms such as rigidity, bradykinesia, and tremor.
  • Adverse Events: The overall incidence of adverse events was comparable between groups; however, treatment-emergent adverse events and treatment discontinuations were more frequent in the IPX203 group. While the total number of adverse events did not differ, the nature of these events and the decision to discontinue treatment were more common with the extended-release formulation.

# Bulgular ne anlama geliyor?

The findings suggest that IPX203 offers a pharmacological advantage in managing motor fluctuations in advanced Parkinson's disease by extending the periods of effective symptom control and reducing "Off-time." The greater improvement in motor function scores indicates a potential clinical benefit in daily functioning, allowing patients to experience more hours of symptom relief. However, the increased frequency of treatment-emergent adverse events and discontinuations highlights a significant tolerability concern. Clinicians considering IPX203 must balance these efficacy gains against the higher likelihood of side effects leading to treatment withdrawal. The number needed to treat (NNT) for benefit must be weighed against the number needed to harm (NNH) regarding discontinuation.

# Klinik önem

While IPX203 demonstrates superior efficacy in controlling motor symptoms and improving "Good On-time," the increased frequency of treatment-emergent adverse events and discontinuations presents a practical barrier to its universal adoption. The overall safety profile remains comparable aside from these specific events. In a clinical setting, the decision to switch from immediate-release to IPX203 should be individualized, considering the patient's tolerance for side effects and their specific symptom profile. Patients experiencing significant motor fluctuations who are tolerant of adverse events may derive substantial benefit. Conversely, patients prone to side effects or those with a history of treatment discontinuation may fare better on immediate-release therapy. Further research with larger sample sizes and longer follow-up is needed to fully characterize the long-term safety and optimal patient selection criteria.

# Sınırlılıklar

The systematic review has several limitations that affect the precision of its conclusions. Only three RCTs with small sample sizes were included, which limits the generalizability of the findings to the broader Parkinson's disease population. There was heterogeneity in study populations and trial designs, contributing to imprecision in the effect estimates and making direct comparisons challenging. Additionally, risk of bias concerns were present across the included studies, potentially influencing the observed treatment effects. Most critically, the review notes limited long-term safety data, and the indirect precision of the effect estimates restricts the confidence with which these results can be applied to broader clinical practice. Future large-scale, long-term RCTs are necessary to validate these findings and establish the place of IPX203 in the therapeutic algorithm for advanced Parkinson's disease.