Alpha-2 Agonist·Psychiatry - ADHD & Stimulants

Guanfacine MR

ADHD in children and adolescents (6-17 years), either as monotherapy or adjunct to stimulants

Authority requiredPBSNON-STIMULANTIntuniv4 mg tablet+2

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At a glance

Max Dose

7 mg/day

Half-life

18 h

Caution: Hypotension

HIGH RISK

Caution: Sedation

COMMON

Cautions

Avoid / Cautions

Known hypersensitivity. Do not use in patients with significant heart block or baseline bradycardia/hypotension. Pregnancy Category B1.

Where it stands

Rapid Summary

Overview

Central Alpha-2A adrenoceptor agonist. Originally a blood pressure medication, now formulated as a modified-release tablet for ADHD. Highly effective for rejection-sensitive, hyperactive, and aggressive ADHD phenotypes.

Clinical Focus

Must never be stopped abruptly due to severe rebound hypertension. Causes profound sedation and hypotension during initiation.

Bottom Line

Guanfacine MR is a non-stimulant alpha-2 agonist for ADHD as monotherapy or adjunct to stimulants, but causes significant sedation and hypotension especially during titration and must not be stopped abruptly.

Formulation & Access

Brand Names

Intuniv

Oral Routes

Do not crush

Modified Release Tablets (1, 2, 3, 4 mg). MUST be swallowed whole. Do not crush, chew, or break.

Prescribing & PBS

Authority Required (PBS). S4.

Indications & Use

Primary

PBSTGA

ADHD in children and adolescents (6-17 years), either as monotherapy or adjunct to stimulants.

Off-Label

OFF

Severe tic disorders, Tourette's syndrome, PTSD hyperarousal.

Clinical Place

The drug of choice for ADHD patients who are highly aggressive, easily triggered/enraged, or have severe tics (which stimulants make worse).

Quick reference

Class & Role

Alpha-2 Agonist — Central Alpha-2A adrenoceptor agonist.

Route / Formulation

Modified Release Tablets (1, 2, 3, 4 mg). MUST be swallowed whole. Do not crush, chew, or break. (Intuniv)

Usual Dose & Max

Start PO 1 mg OD (morning or evening). Titrate by 1 mg/week based on clinical response and weight. Weight-tiered dose limits: max 4 mg/day for 25–34 kg, max 5 mg/day for 35–49 kg, max 7 mg/day for ≥ 50 kg.

Key Indication Doses

ADHD (Children/Adolescents): Start PO 1 mg OD (morning or evening). Titrate by 1 mg/week based on clinical response and weight. Strict weight-tier maximums: max 4 mg/day (25–34 kg), max 5 mg/day (35–49 kg), max 7 mg/day (≥ 50 kg). Discontinuation: Taper the dose down by 1 mg every 3-7 days to prevent hypertensive crisis.

Best Uses

Key Risks

Cardiovascular: Hypotension, bradycardia, syncope. Rebound hypertension if ceased abruptly. Neurological: Somnolence, sedation, fatigue (Extremely common, affects > 40% of patients initially). Metabolic: Weight gain (Unlike stimulants which cause weight loss).

Key Interactions

CYP3A4 inhibitors (Clarithromycin, Ketoconazole) drastically spike Guanfacine levels, causing severe hypotension/bradycardia. Dose must be halved. Inducers (Carbamazepine) require dose doubling. Antihypertensives (Additive BP drop). CNS Depressants (Additive sedation).

Monitoring

Measure BP and HR at baseline, during dose escalations, and periodically. Assess for orthostatic drops. No specific routine laboratory tests required.

Clinical Pearl

Guanfacine is brilliant when combined with Vyvanse/Ritalin. The stimulant fixes the inattention, while the Guanfacine cancels out the stimulant's side effects (it fixes the insomnia, lowers the blood pressure, and stops the tics).

Access

Authority requiredIntuniv4 mg tablet

Brand: Intuniv
PBS status: Authority required
Formulation: Modified Release Tablets (1, 2, 3, 4 mg). MUST be swallowed whole. Do not crush, chew, or break.

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