Guanfacine

UK indication (Intuniv and generic guanfacine prolonged-release tablets): ADHD in children and adolescents aged 6 to 17 for whom stimulants are not suitable, not tolerated or have been shown to be ineffective, as part of a comprehensive programme; initiation under a specialist in childhood and/or adolescent behavioural disorders. Both SmPCs (Intuniv, generic guanfacine): safety and efficacy in adults not established; should not be used in adults. NICE NG87 1.7.10: offer atomoxetine or guanfacine to children aged 5 and over and young people who cannot tolerate methylphenidate or lisdexamfetamine, or whose symptoms have not responded to separate 6-week trials of both (use at age 5 is off-label). NG87 1.7.17: do not offer guanfacine for adults without advice from a tertiary ADHD service (off-label). NG87 1.8.14: if tics are stimulant related, consider changing to guanfacine (children aged 5 and over and young people only). NG87 1.8.12: sustained orthostatic hypotension or fainting on guanfacine: reduce the dose or switch.

Intuniv (Takeda Pharmaceuticals International AG Ireland Branch): 1, 2, 3 and 4 mg prolonged-release tablets; SmPC text revised 5 March 2026; UK launch 2016 (GB authorisation date on eMC 1 January 2021). Guanfacine 1 to 6 mg prolonged-release tablets (Neuraxpharm UK Ltd): first authorised 15 July 2025, SmPC text revised 22 July 2026; same indication and posology; the 5 mg and 6 mg strengths cover the adolescent upper range. Immediate-release guanfacine (not licensed for ADHD in the UK) must not be substituted mg for mg because of the different pharmacokinetic profile.

Start 1 mg once daily, morning or evening. Increase by no more than 1 mg a week, guided by response and tolerability. The interval between dose increases varies with tolerability, clinical safety and local policy or guidelines. Usual maintenance range: 0.05 to 0.12 mg/kg/day.

Baseline: cardiovascular status including BP and heart rate; full concomitant medication history; personal and family history including sudden cardiac or unexplained death; height and weight on a growth chart. ECG is not needed before starting unless NG87 1.7.5 features or a cardiac-risk medicine are present (NG87 1.7.4). During titration and stabilisation: weekly review for somnolence, sedation, hypotension and bradycardia. Then at least every 3 months in the first year (including weight and BMI for obesity risk), then 6-monthly. Somnolence and sedation predominantly at the start and typically lasting 2 to 3 weeks (longer in some): counsel on driving, cycling and machinery. QT prolongation reported post-marketing: caution with QT risk factors or QT-prolonging drugs. Monitor for suicidal ideation (post-marketing reports, mostly with underlying psychiatric disorders) and for aggression or hostility. Rebound hypertension and tachycardia on withdrawal; hypertensive encephalopathy very rarely after abrupt stopping.

CYP3A4/5 inhibitors (ketoconazole, itraconazole, posaconazole, ritonavir, clarithromycin, erythromycin, fluconazole, diltiazem, verapamil, grapefruit juice): increased exposure, hypotension, bradycardia and sedation; 50% dose reduction. CYP3A4 inducers (carbamazepine, rifampicin, phenytoin, phenobarbital, oxcarbazepine, St John's wort): reduced exposure; retitration up to 7 mg. Valproic acid: guanfacine can raise valproate levels; monitor. Antihypertensives: additive hypotension and syncope risk. CNS depressants including alcohol, benzodiazepines, barbiturates, sedating antihistamines and antipsychotics: additive sedation; patients should not drink alcohol. QT-prolonging drugs: generally not recommended given guanfacine's bradycardic effect. No clinically meaningful pharmacokinetic interaction with oral methylphenidate or lisdexamfetamine; combination with a stimulant is specialist-led with BP and pulse monitoring.

Very common: somnolence (40.6% in the pooled trials), headache (27.4%), fatigue (18.1%), upper abdominal pain (12.0%). Sedation 10.2%. Common: decreased appetite, depression, anxiety, affect lability, insomnia, middle insomnia, nightmares, dizziness, lethargy, bradycardia (1.5%), hypotension (3.2%), orthostatic hypotension, vomiting, diarrhoea, nausea, constipation, abdominal discomfort, dry mouth, enuresis, irritability, rash, weight increase (2.9%). Uncommon: hypersensitivity, agitation, aggression, hallucination, convulsion, syncope (0.7%), postural dizziness, first-degree AV block, tachycardia, sinus arrhythmia, pallor, asthma, dyspepsia, pruritus, pollakiuria, asthenia, chest pain, QT prolongation, increased blood pressure, decreased heart rate, raised ALT. Rare: hypersomnia, hypertension, malaise. Very rare: hypertensive encephalopathy (on abrupt discontinuation). Frequency not known: erectile dysfunction. Somnolence, sedation and hypotension are most prominent in the first weeks and diminish thereafter.

Pregnancy: the SmPC states guanfacine is not recommended during pregnancy or in women of childbearing potential not using contraception (limited human data; animal data show reproductive toxicity). No BUMPS/UKTIS patient leaflet exists (checked October 2026); clinicians can contact UKTIS for case-specific advice.

Breastfeeding: the SmPC says transfer into human milk is unknown and a risk to the infant cannot be excluded. BfN (April 2025): no published data; the drug profile suggests it could enter milk easily, so compatibility cannot be assumed; contact the Drugs in Breastmilk information service. Do not advise abrupt discontinuation in either situation.

Not a controlled drug: standard FP10 repeat once stabilised. Specialist initiation and titration; most local shared care protocols require a stable, optimised dose (often 12 weeks) before transfer, and in adults a documented tertiary ADHD service recommendation. Both Intuniv and generic guanfacine are available; switching between them is at the same dose, and families should be told which product to expect. During supply problems, do not allow abrupt stops: bridge with the alternative product or taper per the SmPC.