Guanfacine: Difference between revisions
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{{MedTemplate | {{MedTemplate | ||
| generic = Guanfacine | | generic = Guanfacine | ||
| brand = Intuniv | | brand = Intuniv (extended-release), Tenex (immediate-release) | ||
| classes = Alpha-2 agonist, ADHD medicine | | structure = | ||
| mechanism = Selective | | 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 = Oral | |||
| onset = Gradual; full clinical effect over 2-4 weeks of titration | |||
| duration = ~24 hours (ER formulation supports once-daily dosing) | |||
| 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" />. | |||
}} | }} | ||
== References == | |||
<references /> | |||