NCT06831500

Feasibility Study Assessing the Effect of Carbidopa/Levodopa Ratio on Orthostatic Hypotension in Multiple System Atrophy - Parkinsonian Type and Parkinson Disease.

A Monocentric, Randomized, Double-blind Study to Assess the Feasibility of Conducting a Full-scale Randomized Controlled Trial (RCT) Assessing the Effect of Carbidopa/Levodopa Ratio on Orthostatic Hypotension (OH) in Multiple System Atrophy - Parkinsonian Type (MSA-P) and Parkinson Disease (PD) Patients (CARBIDOH)

• Status: Recruiting
• Phase: Phase 1 / Phase 2
• Study type: Interventional
• Enrollment: 36 (estimated)
• Sponsor: Julien Bally · Academic / Other
• Sex: All
• Age: —
• Healthy volunteers: Not accepted

Summary

This study is aimed at patients with multi-system atrophy - parkinsonian type (P-MSA) or Parkinson's disease (PD) receiving dopaminergic drugs and suffering from orthostatic hypotension (OH). OH is a drop in blood pressure when standing, which can lead to symptoms of dizziness, lightheadedness, a black veil in front of the eyes and, when severe, can lead to fainting. HO is one of the symptoms present in AMS-P and PD. The standard treatment for parkinsonian symptoms of slowness and stiffness is the administration of antiparkinsonian drugs containing dopamine. These dopaminergic drugs always contain 1) levodopa (which is the precursor of dopamine) and 2) an enzyme inhibitor, which may be either benserazide (in the case of Madopar® and its generics) or carbidopa (in the case of Sinemet® or Stalevo® and their generics) and whose role is to potentiate the effect of levodopa. It has long been known that dopaminergic drugs aggravate HO. Through various mechanisms, this worsening of HO is linked as much to levodopa as to the enzyme inhibitor with which it is combined. However, investigators do not know the respective effects of these two molecules on HO. In this study, investigators examine how the ratio of Carbidopa to levodopa affects HO in the various assays of the dopaminergic drug under study.

Conditions

• Multi-system Atrophy - Parkinsonian Type
• Orthostatic Hypotension, Dysautonomic
• Parkinson Disease

Interventions

Type	Name	Description
DRUG	Administration of Carbidopa/levodopa	Participants will perform beat-by-beat orthostatic tests (Schellong tests) before and after intake of single doses of carbidopa:levodopa combinations at 3 different ratios

Timeline

• Start date: 2025-07-18
• Primary completion: 2026-11-01
• Completion: 2026-11-01
• First posted: 2025-02-18
• Last updated: 2026-01-29

Locations

2 sites across 1 country: Switzerland

Regulatory

• FDA-regulated drug study