Could a plant extract ease ADHD in adults? new trial results are in
NCT ID NCT05202327
First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This Phase II trial tested PDC-1421, a capsule made from a plant extract, in 99 adults with ADHD. Participants were randomly assigned to receive the capsule or a placebo for up to 8 weeks. The goal was to see if the treatment could reduce ADHD symptoms and to check its safety.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- PDC-1421 (extract of Radix Polygalae, a plant-based capsule)
- What this could lead to
- If it works, this could point toward a new plant-based option to help ease ADHD symptoms in adults.
- What could go wrong
- This is an early Phase II trial with only 99 people, so results may not apply widely. The treatment may not work better than placebo, and side effects are still being studied.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 2
Tests whether the treatment actually works, and watches for side effects, in a larger group.
- Participants
-
99 people
The number who actually took part.
- Started
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Apr 2022
- Finished
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Apr 2024
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 70 years
- Sex
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Anyone
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. Aged 18-70 years 2. Female subjects of child-bearing potential must test negative to pregnancy and use appropriate birth control method from the beginning of study to the 15 days later after ending of study 3. Subjects must be able to understand and willing to sign informed consent 4. Able to discontinue the use of any psychotropic medications for the treatment of ADHD symptoms at screening 5. Meet strict operational criteria for adult ADHD according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) 6. A total score of 28 or higher of ADHD Rating Scale-Investigator Rated (ADHD-RS-IV) at screening 7. Have a moderate or severe symptom of ADHD with score of 4 or higher in Clinical Global Impression- Severity (CGI-S) at screening Exclusion Criteria: 1. Have any clinically significant concurrent medical condition (endocrine, renal, respiratory, cardiovascular, hematological, immunological, cerebrovascular, neurological, anorexia, obesity or malignancy) that has become unstable and may interfere with the interpretation of safety and efficacy evaluations 2. Have any clinically significant abnormal laboratory, vital sign, physical examination, or electrocardiogram (ECG) findings at screening that, in the opinion of the investigator, may interfere with the interpretation of safety or efficacy evaluations 3. Have known serological evidence of human immunodeficiency virus (HIV) antibody 4. Are pregnant as confirmed by a positive pregnancy test at screening 5. Have QTc values \>450 msec at screening using Fridericia's QTc formula 6. Have current of bipolar and psychotic disorders 7. Have a current major depression disorder, obsessive-compulsive disorder, post-traumatic stress disorder, generalized anxiety disorder, panic disorder and eating disorder (also if treated but not currently symptomatic) NOTE: Comorbid diagnoses identified during screening and baseline are acceptable provided that ADHD is the primary diagnosis and the comorbid diagnoses will not confound study data or impair subject's ability to participate (per the Investigator's judgement and documented in source note). 8. Have any history of a significant suicide attempt, or possess a current risk of attempting suicide, in the investigator's opinion, based on clinical interview and responses provided on the Columbia-Suicide Severity Rating Scale (C-SSRS). 9. Have a history of jailing or imprisonment in the past 6 months due to worsening of symptoms of ADHD
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Cheng Hsin General Hospital
Taipei, 112, Taiwan
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Kaohsiung Chang Gung Memorial Hospital
Kaohsiung City, 83301, Taiwan
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Linkou chang Gung Memorial Hospital
Taoyuan, 33425, Taiwan
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National Taiwan University Hospital
Taipei, 10002, Taiwan
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Taipei veterans General Hospital
Taipei, 112, Taiwan
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University of California, San Francisco
San Francisco, California, 94143, United States
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Other studies related to the condition(s) this trial covers.
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