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SPD503 (Guanfacine HCl)
Guanfacine is an alpha-2A adrenergic receptor agonist that reduces norepinephrine activity in the prefrontal cortex to improve attention and impulse control.
Guanfacine is an alpha-2A adrenergic receptor agonist that reduces norepinephrine activity in the prefrontal cortex to improve attention and impulse control. Used for Attention-deficit/hyperactivity disorder (ADHD) in children and adolescents.
At a glance
| Generic name | SPD503 (Guanfacine HCl) |
|---|---|
| Also known as | Intuniv |
| Sponsor | Shire |
| Drug class | Alpha-2A adrenergic receptor agonist |
| Target | Alpha-2A adrenergic receptor |
| Modality | Small molecule |
| Therapeutic area | Neurology / Psychiatry |
| Phase | Phase 3 |
Mechanism of action
Guanfacine selectively binds to alpha-2A adrenergic receptors in the brain, particularly in the prefrontal cortex, which decreases norepinephrine signaling and enhances working memory and executive function. This mechanism helps reduce symptoms of inattention and hyperactivity-impulsivity. SPD503 is an extended-release formulation designed to provide sustained therapeutic levels throughout the day.
Approved indications
- Attention-deficit/hyperactivity disorder (ADHD) in children and adolescents
Common side effects
- Somnolence
- Fatigue
- Headache
- Dizziness
- Hypotension
- Bradycardia
- Dry mouth
Key clinical trials
- A Study of TAK-503 in Children and Teenagers With Attention Deficit Hyperactivity Disorder (ADHD) (PHASE4)
- Access to Extended Release Guanfacine HCl for Subjects Who Participated in Studies SPD503-315 or SPD503-316 in Europe (PHASE3)
- A Drug Interaction Study of SPD503 and Concerta Administered Alone and In Combination in Normal Healthy Volunteers (PHASE1)
- Efficacy and Safety of SPD503 in Combination With Psychostimulants (PHASE3)
- A Drug Interaction Study of SPD503 and Vyvanse Administered Alone and In Combination in Normal Healthy Volunteers (PHASE1)
- SPD503 (Guanfacine Hydrochloride) in ADHD Plus Oppositional Symptoms (PHASE3)
- Safety and Tolerability of SPD503 and Psychostimulants in Children and Adolescents Aged 6-17 With Attention-Deficit/Hyperactivity Disorder (ADHD) (PHASE2)
- Safety and Efficacy of SPD503 in Treating Attention-Deficit/Hyperactivity Disorder (ADHD) in Children Aged 6-17 (PHASE3)
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
Competitive intelligence
For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:
- SPD503 (Guanfacine HCl) CI brief — competitive landscape report
- SPD503 (Guanfacine HCl) updates RSS · CI watch RSS
- Shire portfolio CI