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PDC-1421

Phase 2

Major Depressive Disorder | Small molecule | Psychiatry |ABVC BioPharma, Inc.|Last Updated: May 6, 2026

Target and mechanism

ModalitySmall molecule

Also known as PDC-1421 Capsule

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials3
Total Enrollment114

FDA Designations

No designations recorded

Clinical trial landscape

PDC-1421 · 5 trials · 2 indications

Phase 2 3Phase 1 2
NCT05202327PDC-1421 Treatment in Adult Patients With ADHDAttention-Deficit Hyperactivity Disorder (ADHD)
COMPLETED99 Analytics
NCT02699086A Study of PDC-1421 Treatment in Adult Patients With Attention-Deficit Hyperactivity Disorder (ADHD)Attention-Deficit Hyperactivity Disorder (ADHD)
COMPLETED6 Analytics
NCT02395978A Phase II Study of PDC-1421 Capsule to Evaluate the Safety and Efficacy in Patients With Major Depressive DisorderMajor Depressive Disorder
COMPLETED72 Analytics
PHASE2COMPLETED
PDC-1421 Treatment in Adult Patients With ADHD
Attention-Deficit Hyperactivity Disorder (ADHD)Unlock trial analytics
PHASE2COMPLETED
A Study of PDC-1421 Treatment in Adult Patients With Attention-Deficit Hyperactivity Disorder (ADHD)
Attention-Deficit Hyperactivity Disorder (ADHD)Unlock trial analytics
PHASE2COMPLETED
A Phase II Study of PDC-1421 Capsule to Evaluate the Safety and Efficacy in Patients With Major Depressive Disorder
Major Depressive DisorderUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of Participants With Improvement ≥ 40% in ADHD-RS-IV From Baseline up to 8 Weeks Treatment
8 weeks

The ADHD-RS-IV with Adult Prompts is an 18-item scale based on the DSM-IV-TR criteria for ADHD that provides a rating of the severity of symptoms. The adult prompts serve as a guide to explore more fully the extent and severity of ADHD symptoms and create a framework to ascertain impairment. The odd-numbered 9 items assess inattentive symptoms and the even-numbered 9 items assess hyperactive-impulsive symptoms. Scoring is based on a 4-point, yielding a possible total score of 0-54. Likert-type severity scale: 0 = Never or Rarely, 1 = Sometimes, 2 = Often, 3 = Very Often. Clinicians should score the highest score that is generated for the prompts for each item. The ADHD-RS-IV was assessed from Visit 1 to Visit 7 by the investigator.

Change of Montgomery-Asberg Depression Rating Scale (MADRS) Total Score From Baseline to Week 6 Compared to Placebo for Part II.
From Baseline to Week 6

The MADRS is a 10-item checklist of depressive symptoms. Each Item is rated on a scale of 0-6, with anchors at 2-point intervals; higher scores indicating more severity (i.e., ranging from 0 \[no sadness\] to 6 extremely despondent\]). The total MADRS score was calculated by summing the ratings of all items. The total MADRS score for this measure ranges from 0 (absence of symptoms) to 60 (maximum severity).

Montgomery-Åsberg Depression Rating Scale (MADRS)
5 weeks

Change in Montgomery-Åsberg Depression Rating Scale (MADRS) total score from baseline to week 1, 2, 3, 4, and 5 in patients taking 1 or 2 PDC-1421 capsules. The MADRS is a 10-item checklist including 1) depression \[apparent\]; 2) depression \[reported\]; 3) loss of interest; 4) suicidal ideation; 5) tension; 6) reduced appetite; 7) insomnia; 8) difficulty in activities; 9) concentration; and 10) pessimism. The MADRS is administered by a trained interviewer. Each item is rated on a scale of 0-6, with anchors at 2-point intervals; higher scores indicating more severity (i.e., ranging from 0 \[no sadness\] to 6 \[extremely despondent\]). The total score is used to define treatment response (≥50% reduction from baseline) and partial response (20-49% reduction from baseline). Remission is defined as a score of \< 10. The following are used as an interpretation of scores: 0 to 6 - normal/symptom absent 7 to 19 - mild depression 20 to 34 - moderate depression \>34 - severe depression

Number of Dose Limiting Toxicity of Physical Examination
baseline to 72 hours

Physical examination, including skin, head, neck, eyes, ears, nose, throat, heart, lungs, abdomen (liver and spleen), neurological examination, lymph node and extremities, is measured at each visit from screening to follow-up.

Number of Dose Limiting Toxicity of Electrocardiograph
baseline to 72 hours

Electrocardiograph (ECG) is measured at each visit. At visit 2, subjects were measured at 1,2, 4, 8, 12 and 24 hours after drug administration.

Number of Dose Limiting Toxicity of Vital Sign
baseline to 72 hours

Vital sign, including heart rate, blood pressure and body temperature, are measured at each visit and at 1,2,3,4,8,12 and 24 hours after drug administration.

Number of Dose Limiting Toxicity of Laboratory Values
baseline to 72 hours

Laboratory tests are composed of hematology and blood chemistry and measured at each visit. Hematology are composed of RBC, WBC, platelets, hematocrit, hemoglobin, prothrombin time (PT) and partial thromboplastin time (aPTT). Blood chemistry are composed of AST, ALT, LDH, total bilirubin, BUN, serum creatinine, free thyroxine (FT4), TSH, sodium, calcium, potassium, glucose, LDL, HDL, cholesterol and HbA1c.

Number of Dose Limiting Toxicity of Columbia-Suicide Severity Rating Scale (C-SSRS)
baseline to 72 hours

C-SSRS is composed of suicidal ideation, intensity of ideation and suicidal behavior and measured at each visit.

Secondary Endpoints

Number of Participants With a CGI Score of 2 or Lower From Baseline up to 8 Weeks Treatment
8 weeks
Change From Baseline up to 8 Weeks in the Sluggish Cognitive Tempo (K-SCT) Score.
8 weeks
Change From Baseline up to 8 Weeks in the ADHD-RS-IV Total Scale.
8 weeks
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
PlaceboPLACEBO_COMPARATORTwo placebo capsules thrice daily for 56 days (8 weeks).
Low-doseEXPERIMENTALOne placebo capsule and 1 PDC-1421 Capsule, thrice daily for 56 days (8 weeks).
High-doseEXPERIMENTALTwo PDC-1421 Capsules thrice daily for 56 days (8 weeks).
Low dose + Low doseEXPERIMENTAL1 PDC-1421 Capsule, trice daily, p.o. after meal for 28 + 28 days
Low dose + High doseEXPERIMENTAL1 PDC-1421 Capsule for 28 days + 2 PDC-1421 Capsules for 28 days, trice daily, p.o. after meals
Part I: 1 PDC-1421 CapsuleEXPERIMENTAL1 PDC-1421 Capsule TID, p.o. after meal for 28 days
Part I: 2 PDC-1421 CapsuleEXPERIMENTAL2 PDC-1421 Capsule TID, p.o. after meal for 28 days
Part II: 2 PDC-1421 CapsuleEXPERIMENTAL2 PDC-1421 Capsule TID, p.o. after meal for 42 days
Part II: 1 PDC-1421 Capsule plus 1 placeboEXPERIMENTAL1 PDC-1421 Capsule plus 1 placebo TID, p.o. after meal for 42 days
Part II: 2 placeboPLACEBO_COMPARATOR2 placebo TID, p.o. after meal for 42 days
1 PDC-1421 CapsuleEXPERIMENTAL1 PDC-1421 Capsule, trice daily, p.o. after meal for 28 days
2 PDC-1421 CapsulesEXPERIMENTAL2 PDC-1421 Capsule, trice daily, p.o. after meal for 28 days
PDC-1421EXPERIMENTALDosage form: 380mg PDC-1421 per Capsule. Dosage: single dose (1, 3, 6, 10 capsule(s)). Frequency: once daily, p.o., after meal. Duration: single dose at Day 1, and observing for three Days.
Placebo controlPLACEBO_COMPARATORDosage form: Capsule. Dosage: single dose (1, 3, 6, 10 capsule(s)). Frequency: once daily, p.o., after meal. Duration: single dose at Day 1, and observing for three Days.

Interventions

NameTypeDescription
PDC-1421 CapsuleDRUGPDC-1421 Capsule is a botanical investigational new drug containing the extract of Radix Polygalae (Polygala tenuifolia Willd.) as the active ingredient.
PlaceboDRUGThe placebo contained corn starch.
PDC-1421DRUG -
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Eligibility Criteria

Age Range18 Years to 70 Years
SexALL
Healthy VolunteersNo
Study Sites6

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 c...

Countries:United StatesTaiwan
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Recent Changes (Last 90 Days)

MEDIUMJun 6, 2026NCT05202327TRIAL_REMOVED: changed
MEDIUMJun 6, 2026NCT05202327TRIAL_REMOVED: changed
MEDIUMJun 6, 2026NCT05202327TRIAL_REMOVED: changed
MEDIUMJun 6, 2026NCT05202327TRIAL_REMOVED: changed
MEDIUMJun 6, 2026NCT05202327TRIAL_REMOVED: changed
MEDIUMJun 6, 2026NCT05202327TRIAL_REMOVED: changed
MEDIUMMay 26, 2026NCT03833206Phase: PHASE2 → PHASE1
LOWMay 24, 2026NCT03833206studyFirstPostDate: changed

Frequently asked questions about PDC-1421

What is PDC-1421 used for?

PDC-1421 is an investigational small molecule being developed for Major Depressive Disorder and Attention-Deficit Hyperactivity Disorder (ADHD). It is currently in Phase 2 clinical development and has been studied in both conditions, with completed trials in depression and ADHD.

Who makes PDC-1421?

PDC-1421 is being developed by ABVC BioPharma, Inc., a company traded under the ticker ABVC. The drug is in Phase 2 clinical development for psychiatric indications including Major Depressive Disorder and ADHD.

What phase is PDC-1421 in?

PDC-1421 is in Phase 2 clinical development. It is an investigational drug and has not been approved by regulatory authorities. Clinical trials have been completed for both Major Depressive Disorder and ADHD, with one active trial ongoing.

What clinical trials is PDC-1421 in?

PDC-1421 has been studied in several clinical trials. These include NCT01774045, a Phase 1 dose escalation study in depression; NCT02395978, a Phase 2 study in Major Depressive Disorder; NCT02699086, a Phase 2 study in ADHD; and NCT05202327, a Phase 2 study in adult ADHD patients.

Is PDC-1421 the same as PDC-1421 Capsule?

Yes, PDC-1421 is also known as PDC-1421 Capsule. The capsule formulation has been used in clinical trials for Major Depressive Disorder and ADHD, and the drug is being developed by ABVC BioPharma, Inc.

How does PDC-1421 work?

The mechanism of action for PDC-1421 has not been disclosed in available information. It is being studied as a small molecule treatment for Major Depressive Disorder and ADHD, but its specific molecular target has not been publicly detailed.