Guanfacine: Difference between revisions
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{{MedTemplate | {{MedTemplate | ||
| generic | | generic = Guanfacine | ||
| brand | | brand = Intuniv (extended-release), Tenex (immediate-release) | ||
| structure | | structure = | ||
| classes | | classes = [[:Category:Alpha-2 adrenergic agonists|Alpha-2 adrenergic agonist]], [[:Category:ADHD medicines|ADHD medicine]], [[:Category:Antihypertensives|Antihypertensive (historical)]] | ||
| | | uses = <vote slug="adhd-use">Attention-deficit/hyperactivity disorder (monotherapy or adjunct to psychostimulants, ages 6-17)</vote>, <vote slug="tic-disorders-use">Tic disorders / Tourette syndrome (off-label)</vote>, <vote slug="opioid-withdrawal-adjunct-use">Opioid withdrawal adjunct (off-label)</vote>, <vote slug="ptsd-nightmares-use">PTSD-associated nightmares and hyperarousal (off-label, selected populations)</vote>, <vote slug="hypertension-historical-use">Hypertension (historical indication, largely supplanted by other classes)</vote> | ||
| | | starting_dose = Intuniv ER 1 mg PO once daily; titrate by 1 mg/week as tolerated to clinical response | ||
| | | preparations = Extended-release tablets 1, 2, 3, 4 mg (Intuniv); immediate-release tablets 1, 2 mg (Tenex) | ||
| | | fda_max = 7 mg/day in children and adolescents; weight-based ceiling (~0.12 mg/kg/day) applies in smaller patients | ||
| | | pill_id = | ||
| routes | | routes = Oral | ||
| onset | | onset = Gradual; full clinical effect over 2-4 weeks of titration | ||
| duration | | duration = ~24 hours (ER formulation supports once-daily dosing) | ||
| halflife | | halflife = ~17-18 hours (Intuniv ER); ~17 hours (immediate-release)<ref name="intuniv-label">FDA Prescribing Information, Intuniv (guanfacine extended-release), Shire/Takeda, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/022037s009lbl.pdf</ref> | ||
| bioavailability = ~58% (extended-release); ~80% (immediate-release)<ref name="intuniv-label" /> | |||
| pregnancy = Limited human data. Animal studies show fetal effects at maternally toxic doses; use only if benefits justify the potential risk.{{citation needed}} | |||
| legal = [[USLegal:Prescription only|Rx-only]] in US. Not a controlled substance, which is a meaningful contrast to the psychostimulant alternatives for ADHD<ref name="intuniv-label" /> | |||
| | | mechanism = <vote slug="guanfacine-mech-claim">Selective postsynaptic α2A-adrenergic receptor agonist. In the prefrontal cortex, α2A activation on pyramidal-neuron dendritic spines strengthens working-memory and attention-regulation circuits by closing HCN channels and reducing cyclic-AMP-driven "noise" from competing inputs. The peripheral antihypertensive effect (the historical indication) reflects α2 agonism in brainstem sympathetic outflow regions.</vote> Sedation and hypotension are the dose-limiting effects; gradual titration and bedtime or split dosing mitigate both. Abrupt discontinuation can precipitate rebound hypertension, particularly with long-standing use<ref name="intuniv-label" />. | ||
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== References == | |||
<references /> | |||
Latest revision as of 06:16, 23 May 2026
Guanfacine
Intuniv (extended-release), Tenex (immediate-release)
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Summary
Pharmacy
Starting dose
Intuniv ER 1 mg PO once daily; titrate by 1 mg/week as tolerated to clinical response
Preparations
Extended-release tablets 1, 2, 3, 4 mg (Intuniv); immediate-release tablets 1, 2 mg (Tenex)
US FDA Max
7 mg/day in children and adolescents; weight-based ceiling (~0.12 mg/kg/day) applies in smaller patients
Pharmacology
Routes
Oral
Onset
Gradual; full clinical effect over 2-4 weeks of titration
Duration
~24 hours (ER formulation supports once-daily dosing)
Half-life
~17-18 hours (Intuniv ER); ~17 hours (immediate-release)[1]
Bioavailability
~58% (extended-release); ~80% (immediate-release)[1]
Pregnancy
Limited human data. Animal studies show fetal effects at maternally toxic doses; use only if benefits justify the potential risk.[citation needed]
Legal status
Purported mechanism
Selective postsynaptic α2A-adrenergic receptor agonist. In the prefrontal cortex, α2A activation on pyramidal-neuron dendritic spines strengthens working-memory and attention-regulation circuits by closing HCN channels and reducing cyclic-AMP-driven "noise" from competing inputs. The peripheral antihypertensive effect (the historical indication) reflects α2 agonism in brainstem sympathetic outflow regions.0 Sedation and hypotension are the dose-limiting effects; gradual titration and bedtime or split dosing mitigate both. Abrupt discontinuation can precipitate rebound hypertension, particularly with long-standing use[1].
References
- ↑ 1.0 1.1 1.2 1.3 FDA Prescribing Information, Intuniv (guanfacine extended-release), Shire/Takeda, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/022037s009lbl.pdf