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Surface here is educational only; do not use without medical supervision. Our editorial verdict is SKIP-FOR-NOW — current cost / risk / redundancy puts it below the line.
Guanfacine
Selective α2A-adrenergic agonist (Shire/Takeda's Intuniv ER) — A-tier evidence as ADHD adjunct in kids/adolescents, B-tier mechanistic…
Aliases (5)
Overview
What is Guanfacine?
Guanfacine (Intuniv ER, Tenex IR) is a selective alpha-2A adrenergic agonist FDA-approved for ADHD (ER form) and hypertension (IR form). More cognitively-targeted than clonidine due to alpha-2A selectivity.
Key Benefits
Improves working memory and prefrontal cortex function in ADHD, reduces impulsivity and emotional dysregulation, useful as ADHD adjunct or monotherapy. Less sedating than clonidine. Improves sleep quality in stim users.
Mechanism of Action
Selectively agonizes postsynaptic alpha-2A receptors on prefrontal cortex pyramidal neurons, strengthening working memory networks via inhibition of cAMP and HCN channels. More PFC-targeted vs clonidine's broad alpha-2 effects.
Pharmacokinetics
▸Brand options5 known
StatusPrescription-only (US, EU, UK, AU, CA); not DEA-scheduled
Research Protocols
Disclaimer: These are commonly discussed research protocols and not medical advice.
Peptide Interactions
orthogonal mechanism, on-label combination, useful for residual symptoms and stimulant-induced sleep disruption / impulsivity rebound. Not relevant-to-archet…
directly opposite vectors (eugeroic vs sedative). For the user, this is the load-bearing reason guanfacine is wrong. Guanfacine would actively undercut modaf…
additive sedation.
additive BP-lowering and bradycardia. Specifically: stacking guanfacine + propranolol = unwanted compounded bradycardia.
raise guanfacine exposure 2-3× → severe sedation/hypotension.
cut exposure ~70% → loss of efficacy.
theoretical risk of hypertensive crisis if MAOI is non-selective; with selegiline at MAO-B-selective doses (the user's V stack conditional), risk is minimal …
can blunt the antihypertensive effect.
Quality Indicators
Pharmacy-dispensed, intact packaging
Prescription tablets in original sealed packaging from a licensed pharmacy.
Generic vs branded
Generics are usually fine but bioavailability can vary slightly; track if you switch.
Unbranded blister or counterfeit risk
Counterfeit pharmaceuticals are a known issue; verify pharmacy and lot if buying internationally.
What to Expect
- Day 1PK-driven acute peak per administration. Verify dose tolerated.
- Week 1Steady-state reached for most daily-dosed pharma.
- Week 2-4Therapeutic effect established; titration window if needed.
- Long-termPeriodic monitoring per drug class (labs, BP, ECG as applicable).
Side Effects & Safety 14
Side Effects
- 1Somnolence / sedation: 36-40% — the dominant side effect; reason guanfacine is sedating-by-default.
- 2Headache: 28%
- 3Fatigue: 20%
- 4Decreased appetite: 12-15% (much less than stimulants)
- 5Abdominal pain: 10-12%
- 6Dry mouth: 10-15%
- 7Dizziness: 10-15% (orthostatic component)
- 8Bradycardia — clinically significant in some, monitor HR.
- 9Hypotension / orthostatic hypotension (~1% symptomatic, but BP lowering is dose-related and common)
- 10Insomnia paradox (small subset)
- 11Irritability / mood changes
- 12Constipation
- 13Erectile dysfunction at higher chronic doses
- 14Weight gain (small effect, opposite of stimulants)
When to Stop
- Severe hypotension / syncope — case reports, particularly with overdose or rapid titration. PMC10846796 documents an "unexpected severe hypotension" case.
- Severe bradycardia / AV block — rare but documented; ECG considerations in patients with conduction disease.
- Rebound hypertension on abrupt withdrawal — well-documented for clonidine, less common but real for guanfacine. Always taper.
- Heart-block exacerbation in patients with pre-existing AV nodal disease.
- Intentional or accidental overdose — prolonged bradycardia and hypotension reported (PMC4202905); narrow-margin drug in pediatric ingestion contexts.
- First 2-3 weeks of titration — sedation peaks; dizziness; orthostatic episodes most likely.
- Dose increases — re-watch BP/HR for 1 week after each step.
- Discontinuation — never abrupt; taper over 1-2 weeks minimum to avoid rebound.
References
Arnsten Lab — Guanfacine for the Treatment of PFC Disorders (Yale)
mechanism and translation overview from the lab that developed Intuniv ER
View StudyArnsten 2020 — Guanfacine's mechanism of action in treating prefrontal cortical disorders: successful translation across species (PubMed 33075480)
the canonical mechanism review
View StudyAvery, Franowicz et al. 2000 — α2A-Adrenoceptor agonist guanfacine increases regional cerebral blood flow in dorsolateral PFC of monkeys (Neuropsychopharmacology)
primate fMRI/blood flow data
View StudyArnsten 2023 — Scientific rationale for α2A-adrenoceptor agonists in neuroinflammatory cognitive disorders (Molecular Psychiatry)
recent mechanism extension
View StudyJäkälä et al. 1999 — Guanfacine, but not clonidine, improves planning and working memory in humans (Neuropsychopharmacology)
the positive single-dose healthy-volunteer trial
View StudyMüller et al. 2005 — Lack of effects of guanfacine on executive and memory functions in healthy male volunteers (Psychopharmacology)
null healthy-volunteer trial
View StudyRamos et al. 2018 — Guanfacine treatment for prefrontal cognitive dysfunction in older participants RCT (Neuropsychopharmacology, PMC6503670)
null in older adults
View StudySallee et al. 2009 — Pivotal Intuniv ER trial in pediatric ADHD
pivotal regulatory study
View StudyIwanami et al. 2020 — Long-term safety and efficacy of guanfacine ER in adults with ADHD, Japan phase-3 extension (PMC7531113)
adult ADHD on-label data
View StudyADHDevidence.org 2024 — Updated meta-analysis supports efficacy of guanfacine in treating ADHD
n=2,623 across 11 studies
View StudyCDA-AMC 2025 — Guanfacine ER reimbursement review (Canada)
recent regulatory efficacy review
View StudyFrontiers 2025 — Treatment of affective dysregulation in ADHD with guanfacine (study protocol)
current research direction
View StudyINTUNIV (guanfacine) extended-release tablets prescribing information (FDA)
full label
View StudyPsychSceneHub — Guanfacine and clonidine for ADHD: what's the difference
clinical comparison
View StudyChildress 2023 — Alpha-2 agonists for ADHD review (PMC10204383)
α2A vs α2A/B/C selectivity comparison
View StudySevere Hypotension Associated with Guanfacine — case report (PMC10846796)
adverse-event documentation
View StudyProlonged Bradycardia and Hypotension Following Guanfacine ER Overdose (PMC4202905)
overdose presentation
View StudyAAFP 2011 — Guanfacine (Intuniv) for ADHD clinical reference
primary care reference
View StudyMayo Clinic — Guanfacine oral route side effects and dosage
patient-facing reference
View StudyHow was your experience with this compound?
Anonymous · one vote per session · results below at 5+ votes.
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