A Phase 2 interventional study of Guanfacine Hydrochloride Immediate Release and Placebo in Hyperactivity in Children With Down Syndrome and Impulsivity in Children With Down Syndrome, sponsored by Rachel G. Greenberg, MD, MB, MHS. Terminated at 14 sites in United States. Open to participants aged 6 Years to 12 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-17.
Sponsored by Rachel G. Greenberg, MD, MB, MHS · Phase 2, Interventional, and Treatment
The primary purpose of this study is to determine efficacy of guanfacine immediate release (GIR) for the treatment of hyperactivity/impulsivity and inattention in children 6-12 years of age with Down syndrome (DS) after 8 weeks of treatment.
This is a randomized, double-blind, placebo-controlled flexibly dosed trial of guanfacine immediate release (GIR) in children with Down syndrome (DS) and symptoms of hyperactivity, inattention, and impulsivity. Participants will undergo a screening period of up to 29 days. Eligible participants meeting study criteria will be randomized 2:1 GIR or placebo. There are a total of up to 4 in person visits (screening, baseline, at Week 4, and at Week 8). Participants will receive GIR or placebo for up to 8 weeks. Weekly dose escalation will be determined via a telephone assessment at Weeks 1-3 and Weeks 4-7. Unmasking of participant and site staff will occur at the week 8, in-person visit. After unmasking, participants who were randomized to receive GIR will be given the option to 1) remain on GIR and to transition to open-label GIR per standard of care or 2) taper off of GIR. A Telephone Safety Assessment will be conducted for all participants, at 5 (+2) days after final study product administration. Blood specimens will be collected at the Week 4 and Week 8 visits for Pharmacokinetic (PK) analyses and lab assessments. Participant data will be collected via a daily study diary and study measures completed at screening/baseline, Week 4 and Week 8. Parents/Caregivers will need to complete the Study Diary during the bridge/taper period for those who are in the GIR arm.
123 studies on the registry are indexed under Spasm; 7 are open to participants now.
This study's enrollment of 3 is below the median of 80 across 104 interventional studies indexed under Spasm.
Browse Spasm studies →This is the only study on the registry with Rachel G. Greenberg, MD, MB, MHS as lead sponsor.
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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.
Participant has symptoms of hyperactivity, inattention and impulsivity manifested as minimum scores of the following rating scales within 30 days of randomization:
Exclusion:
Participant has received any of the following concomitant medication classes within 30 days of randomization:
Participant has a cardiac-related condition including:
Participant has known impending or renal failure defined as:
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.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
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.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
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.
Eligible participants will receive GIR for up to 8 weeks. The treatment period will consist of study product administration from day 0 through day 56 with a masked dose-escalation period from day 0 through day 49.
Drug: Guanfacine Hydrochloride Immediate Release
Eligible participants will receive Placebo for up to 8 weeks.The treatment period will consist of study product administration from day 0 through day 56 with a masked dose-escalation period from day 0 through day 49.
Drug: Placebo
0.5 mg capsules
Matching placebo capsule
Change in parent-rated ABC-H (Aberrant Behavior Checklist-Hyperactivity) subscale core
Change from baseline to Week 8 of the ABC-H subscale score. The ABC-H is a subscale of the ABC. Each of the 16 items is scored as 0 (never a problem), 1 (slight problem), 2 (moderately serious problem), or 3 (severe problem). The total score range is 0 to 48, where a higher score indicates endorsement of greater hyperactivity. Rating based on patient's behavior in last 4 weeks.
Time frame: Baseline to Week 8
Change in parent-rated ABC-H (Aberrant Behavior Checklist-Hyperactivity) subscale core
Change from baseline to Week 4 of the ABC-H subscale score. The ABC-H is a subscale of the ABC. Each of the 16 items is scored as 0 (never a problem), 1 (slight problem), 2 (moderately serious problem), or 3 (severe problem). The total score range is 0 to 48, where a higher score indicates endorsement of greater hyperactivity. Rating based on patient's behavior in last 4 weeks.
Time frame: Baseline to Week 4
Proportion of participants with a CGI-I (Clinical Global Impression-Improvement) score of 2 or better at Week 4
CGI-I specific to hyperactivity, inattention and impulsivity behaviors. The CGI-I is a seven-point scale that requires the clinician to assess how much the patient's illness has improved or worsened relative to a baseline state at the beginning of the intervention. 1 = Very much improved, 2 = Much improved, 3 = Minimally improved, 4 = No change, 5 = Minimally worse, 6 = Much worse, 7 = Very much worse.
Time frame: Baseline to Week 4
Proportion of participants with a CGI-I (Clinical Global Impression-Improvement) score of 2 or better at Week 8
CGI-I specific to hyperactivity, inattention and impulsivity behaviors. The CGI-I is a seven-point scale that requires the clinician to assess how much the patient's illness has improved or worsened relative to a baseline state at the beginning of the intervention. 1 = Very much improved, 2 = Much improved, 3 = Minimally improved, 4 = No change, 5 = Minimally worse, 6 = Much worse, 7 = Very much worse.
Time frame: Baseline to Week 8
Safety of GIR (guanfacine immediate release)
Number of participants with adverse events (AEs), serious adverse events (SAEs), or events of special interest (ESIs).
Time frame: Baseline through Week 8
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — All data is uploaded into the National Institute of Health Data and Specimen Hub (DASH) at the end of the study (de-identified). Samples are also shared with DASH for future use.
Supporting information: Study protocol, Informed consent form
Time frame: Data will be uploaded to the repository within 2 years of study completion. It will be maintained in the repository indefinitely.
Access criteria: In order to have access, researchers have to complete a Data access request. NICHD will review the request and either approve or deny it. IRB approval must be obtained by the researcher to access the data. https://dash.nichd.nih.gov/Resource/DataRequestChecklist
Data sharing details ↗ · dash.nichd.nih.gov
Ran from Dec 2024 to primary completion in May 2025, 5 months.
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This study is terminated, as verified in Apr 2026. You cannot join it, but the record below documents what was studied.
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