A Phase 1/2 interventional study of Clarithromycin (Not used as of 4/2020) and Placebo (Not used as of 4/2020) in Parkinson Disease, sponsored by Nicolaas Bohnen, MD, PhD. Completed at 1 site in United States. Open to participants aged 50 Years and older. Per ClinicalTrials.gov, last updated 2023-01-10.
Sponsored by Nicolaas Bohnen, MD, PhD · Phase 1/2, Interventional, and Other
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Among 1,649 studies in Parkinson Disease with a site in United States — 304 open to participants now, 387 under way, 7 of them phase 3. Parkinson Disease · United States.
Among the 1,649 studies in Parkinson Disease with a site in United States, this one is the 645th largest by enrollment of the 1,256 interventional ones that give a count, is one of 90 that started in 2018, is one of 51 in phase 1/2, and was the 837th registered.
4,576 studies on the registry are indexed under Parkinson Disease; 1,087 are open to participants now.
Browse Parkinson Disease studies →304 of the 1,649 studies in Parkinson Disease with a site in United States are open now. Recruiting first, the newest first:
The Cleveland Clinic · Sites in United States
Ages 18+
University of Colorado, Denver · Sites in United States
Ages 45–75
University of Minnesota · Sites in United States
Ages 18+
Hoffmann-La Roche · Sites in United States, China, United Kingdom
Ages 40–85
Medical University of South Carolina · Sites in United States
Ages 50–85
A study can be open while its sites in United States have not opened yet or have stopped. Only those recruiting at a site in United States →
Of the 750 Parkinson Disease studies recruiting now, 312 (42%) set no upper age limit and 127 (17%) stop at 75 or younger; 64 take children under 18; 190 take healthy volunteers.
This study: 50 Years and older · all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
1,649 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 226 · Phase 2 304 · Phase 3 145 · Phase 4 75
First in 1991; this study’s year is marked. 90 started in 2018.
By drug class, each counting the studies that test any of its medicines:
This study's enrollment of 34 is below the median of 40 across 3,355 interventional studies indexed under Parkinson Disease.
Median enrollment 36 across the 1,256 interventional studies, 78 across the 379 observational. Of the 1,139 that completed or were terminated, 435 (38%) have results posted.
This tab as a report to print or save as PDF → With an account.
470 of 1,649 have an industry lead sponsor. The 10 most frequent:
Nicolaas Bohnen, MD, PhD is the lead sponsor of 2 studies on the registry; none are open to participants now.
Nicolaas Bohnen, MD, PhD has 2 studies filed under Parkinson Disease — fewer than ten, so there is no comparison to draw.
137 of the studies in Parkinson Disease with a site in United States that are under way reach primary completion within a year, 1 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT06976268Phase 3Biohaven Therapeutics Ltd.A Study to Determine if BHV-8000 is Effective, Safe and Tolerable as a Treatment for Adults Living With Early Parkinson's Disease | 2027-08 |
| NCT06098612Massachusetts General HospitalPET Imaging Evaluation of [11C]SY08 | 2026-11 |
| NCT06489483University of Texas Southwestern Medical CenterAction Regulation Behavioral | 2026-11 |
| NCT05558189Stanford UniversityVibrotactile Coordinated Reset for the Treatment of Post Surgery Refractory Parkinson's Disease Patients | 2026-11-21 |
| NCT06773962TrueBinding, Inc.A Phase 2a Multicenter Clinical Trial of TB006 in Participants With Parkinson's Disease | 2026-11-28 |
Add all 137 to your calendar (.ics) → With an account.
Among the 1,649 studies in Parkinson Disease with a site in United States, from their registry updates:
This tab as a report to print or save as PDF → With an account.
The arm of this study evaluates possible GABA-A receptor target engagement effects of the FDA-approved medication, transdermal flumazenil (added 4/2020, replaced clarithromycin), in the setting of Parkinson's disease. Half of the subjects will receive transdermal flumazenil for 7-10 days, and half will receive a placebo. [11C]Flumazenil GABA-A receptor PET imaging will be used to assess target engagement effects. Note [11C]Flumazenil GABA-A receptor PET was not performed as part of the transdermal flumazenil study because of a Covid pandemic research amendment.
This study focuses on neurochemical changes in the brain that occur in Parkinson's disease. In particular we will be looking a neurotransmitter called GABA. In some Parkinson's disease patients we see too much GABA activity in the brain. This target engagement study examines the target engagement effect of GABA-A receptor modulation by transdermal flumazenil (previously clarithromycin). [11C]-flumazenil Positron Emission Tomography (PET) imaging results will be used to assess for possible GABA-A receptor target engagement effects of transdermal flumazenil (previously clarithromycin). Note [11C]Flumazenil GABA-A receptor PET was not performed as part of the transdermal flumazenil study because of a Covid pandemic research amendment.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Additional Exclusion Criteria for Flumazenil sub-studies:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clarithromycin 250mg (1 capsule) will be taken orally twice a day for 3 days and if tolerated will be increased to 500mg (2 capsules) orally twice a day for 4-6 days.
Drug: Clarithromycin (Not used as of 4/2020)
Placebo will be taken exactly as the clarithromycin arm: 1 capsule orally twice a day for 3 days and if tolerated will be increased to 2 capsules orally twice a day for 4-6 days.
Drug: Placebo (Not used as of 4/2020)
Added in April 2020. Subjects will take 18mg transdermal application every 3-4 hrs dispensed as 3 dispenser bottle clicks of 0.25 ml each, while awake for 3 days then if no side-effects subjects will increase to 36mg transdermal application every 3-4 hrs dispensed as 6 dispenser bottle clicks of 0.25 ml each, while awake.
Drug: Transdermal flumazenil (Added 4/2020)
Added in April 2020. Placebo will be taken exactly as the transdermal flumazenil arm: Subjects will take 18mg transdermal application every 3-4 hrs dispensed as 3 dispenser bottle clicks of 0.25 ml each, while awake for 3 days then if no side-effects subjects will increase to 36mg transdermal application every 3-4 hrs dispensed as 6 dispenser bottle clicks of 0.25 ml each, while awake.
Drug: Placebo (Added 4/2020)
Drug page: Clarithromycin
Clarithromycin (generic) capsule 250mg each
Also known as: Biaxin
Lactose in a gel capsule
Drug page: Flumazenil
Transdermal flumazenil 24mg/mL
Transdermal placebo
Also known as: Placebo cream
Change in Quantitative Biomechanics 1 (Clinical Motor Ratings MDS-UPDRS)
We will use the total Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III - motor scale rating scores to assess motor function. Scale from 0-132, higher scores indicate worse motor outcomes. Outcome measure was collected during dopaminergic medication ON state.
Time frame: Day 1 (before treatment administration), day 7 (after 7 days of treatment), and day 14 (7 days of treatment discontinuation).
Change in Quantitative Biomechanics 2 (MiniBESTest Dynamic Balance Scale Sensory Subscore)
MiniBEST sensory subscore measures an individual's ability to maintain balance under conditions of sensory constrain and unstable/inclined standing surface. It is is computed as a sum of MiniBEST items 7, 8, and 9.The score ranges from 0 to 6, with 0 indicating inability to balance under all of the condition, and 6 indicating no difficulty in maintaining balance under any of the conditions (lower score indicates worse balance). Outcome measure was collected during dopaminergic medication ON state.
Time frame: Day 1 (before treatment administration), day 7 (after 7 days of treatment), and day 14 (7 days of treatment discontinuation).
| Milestone | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Dropped in 04/2020) |
|---|---|---|---|
| Started | 11 | 11 | 3 |
| Completed | 11 | 11 | 3 |
| Not completed | 0 | 0 | 0 |
We will use the total Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III - motor scale rating scores to assess motor function. Scale from 0-132, higher scores indicate worse motor outcomes. Outcome measure was collected during dopaminergic medication ON state.
| units on a scale | Transdermal Flumazenil (Active) | Placebo Cream | Clarithromycin (Active or Placebo) |
|---|---|---|---|
| Day 1 | 38 (27.5 to 44.5) | 34 (30 to 47) | 28 (25.50 to 33.00) |
| Day 7 | 36.75 (29.75 to 52) | 31.50 (25.375 to 43.375) | 23.50 (21.25 to 26.75) |
| Day 14 | 32.75 (26.375 to 47.375) | 34 (29.5 to 40) | 22 (19.5 to 23.0) |
MiniBEST sensory subscore measures an individual's ability to maintain balance under conditions of sensory constrain and unstable/inclined standing surface. It is is computed as a sum of MiniBEST items 7, 8, and 9.The score ranges from 0 to 6, with 0 indicating inability to balance under all of the condition, and 6 indicating no difficulty in maintaining balance under any of the conditions (lower score indicates worse balance). Outcome measure was collected during dopaminergic medication ON state.
| units on a scale | Transdermal Flumazenil (Active) | Placebo Cream | Clarithromycin (Active or Placebo) |
|---|---|---|---|
| Day 1 | 5.54 ± 0.69 | 6 ± 0 | 6 ± 0 |
| Day 7 | 5.82 ± 0.40 | 6 ± 0 | 5.67 ± 0.58 |
| Day 14 | 6 ± 0 | 5.82 ± 0.60 | 6 ± 0 |
Collected over Up to 14 days.. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Transdermal Flumazenil (Active) | 0/11 (0%) | 0/11 (0%) | 0/11 (0%) |
| Placebo Cream | 0/11 (0%) | 0/11 (0%) | 0/11 (0%) |
| Oral Clarithromycin (Dropped in 04/2020) | 0/3 (0%) | 0/3 (0%) | 0/3 (0%) |
Parkinson's disease patients age 50 years or older. Some, but not all, participants in the Clarithromycin arm were randomized, and only few completed study procedures because of premature termination of the trial due to an FDA safety risk warning of Clarithromycin, precluding any meaningful analysis. Consequently, this study arm was replaced by the transdermal Flumazenil arm.
| Age, Continuous(years) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| Mean | 72.09 ± 4.41 | 70.27 ± 3.80 | 66.33 ± 5.13 | 70.6 ± 4.43 |
| Sex: Female, Male(Participants) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| Female | 3 | 1 | 1 | 5 |
| Male | 8 | 10 | 2 | 20 |
| Ethnicity (NIH/OMB)(Participants) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| Hispanic or Latino | 0 | 0 | 0 | 0 |
| Not Hispanic or Latino | 11 | 11 | 3 | 25 |
| Unknown or Not Reported | 0 | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 | 0 |
| Asian | 0 | 0 | 0 | 0 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 | 0 |
| Black or African American | 0 | 0 | 0 | 0 |
| White | 11 | 11 | 3 | 25 |
| More than one race | 0 | 0 | 0 | 0 |
| Unknown or Not Reported | 0 | 0 | 0 | 0 |
| Region of Enrollment(participants) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| United States | 11 | 11 | 3 | 25 |
| MiniBEST Sensory Subscore(units on a scale) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| Mean | 5.27 ± 1.1 | 5.81 ± 0.40 | 6 ± 0 | 5.6 ± 0.82 |
| Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III(units on a scale) | Transdermal Flumazenil (Active) | Placebo Cream | Oral Clarithromycin (Active or Placebo) | Total |
|---|---|---|---|---|
| Median | 45 (38.5 to 57) | 41.5 (37 to 49.25) | 40.50 (33.00 to 45.25) | 43.5 (36.00 to 51.50) |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Ran from Jan 2018 to primary completion in Dec 2021, 46 months.
Results were first posted in Jan 2023, 1 year 1 month after primary completion.
Of 55 phase 1/2 interventional studies under Parkinson Disease, half reached primary completion within 25 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 53. This study's 46 months is above that.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Dec 2022. You cannot join it, but the record below documents what was studied.
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Studies of the drugs tested here: Clarithromycin · Flumazenil
Nicolaas Bohnen, MD, PhD