Guanfacine
| Evidence Level: L5 | Predicted Indications: 7 |
Table of Contents
Guanfacine: Faciodigitogenital syndrome
One-Sentence Summary
Guanfacine is an alpha-2A adrenergic agonist, originally used to treat hypertension and attention deficit hyperactivity disorder (ADHD). The TxGNN model predicts it may be effective for Tourette syndrome, the highest-evidence candidate among the ten predictions reviewed (the model’s top-ranked prediction, faciodigitogenital syndrome, has no supporting evidence). Currently, 2 clinical trials (one Phase 3 randomised controlled trial, one Phase 4 study) and 19 publications support this direction. Both trials are small.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not recorded in the local data |
| Predicted New Indication | Faciodigitogenital syndrome |
| TxGNN Prediction Score | 0.9997 |
| Evidence Level | L5 (see note under Clinical Trial Evidence) |
| Australia Market Status | Listed on the PBS Schedule (1 of 1 items) – TGA (ARTG) registration status is not included in this data |
| Number of PBS Items | 1 (valid: 1) |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available in the data compiled for this report. Guanfacine is known to be a selective alpha-2A adrenergic agonist. It strengthens prefrontal cortical network signalling and reduces noradrenergic tone. It is already used for ADHD.
Tics in Tourette syndrome involve prefrontal-striatal circuits and noradrenergic modulation. About half of children with Tourette syndrome also have ADHD. Stimulants, the usual ADHD treatment, can worsen tics, so an alpha-2 agonist that treats both conditions is clinically attractive. Guanfacine already appears in pharmacological management reviews and guidelines for tic disorders, including the European clinical guidelines (PMID 34757514).
The other nine predictions are much weaker. Most have no trials or publications. “Specific developmental disorder” largely overlaps with the existing ADHD indication, so it is closer to a label extension than a new use. Migraine has only indirect support (commentary and hypothesis papers). For manic bipolar affective disorder, the guanfacine-specific literature reports secondary mania in children, which is a potential harm signal.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrolment | Key Findings |
|---|---|---|---|---|
| NCT00004376 | Phase 3 | Completed | 35 | Randomised, double-blind, placebo-controlled trial of guanfacine for safety and efficacy in children and adolescents with Tourette syndrome or chronic tic disorder and ADHD (1994–2000) |
| NCT01547000 | Phase 4 | Completed | 34 | Multi-site pilot study of extended-release guanfacine (Intuniv) for tolerability and efficacy in children with Tourette syndrome (2012–2016) |
Note on evidence level: The L1 grading follows the data compiled for this report. Strictly, L1 requires two or more completed Phase 3 RCTs, and only one Phase 3 trial (n=35) is listed. A conservative reading would be L2. No ANZCTR trials were identified in the data.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 34757514 | 2022 | Clinical guideline | Eur Child Adolesc Psychiatry | European guidelines (v2.0) on pharmacological treatment of Tourette syndrome and tic disorders |
| 27132945 | 2016 | Systematic review | J Child Psychol Psychiatry | Treatments for Tourette syndrome in children and young people |
| 34286606 | 2021 | Systematic review | J Psychopharmacol | Quality of evidence for pharmacological treatment of Tourette syndrome is limited |
| 31061209 | 2019 | Systematic review | Neurology | Comprehensive review of tic treatments in Tourette syndrome and chronic tic disorders |
| 12469007 | 2002 | Double-blind placebo-controlled pilot | Clin Neuropharmacol | Four-week study of guanfacine in 24 children with mild Tourette syndrome |
| 19625978 | 2009 | Meta-analysis | J Am Acad Child Adolesc Psychiatry | Treatment of ADHD in children with comorbid tic disorders |
| 7559307 | 1995 | Clinical experience | J Am Acad Child Adolesc Psychiatry | Preliminary experience with guanfacine in comorbid ADHD and Tourette syndrome |
| 37378108 | 2023 | Case series | Cureus | Guanfacine plus aripiprazole improved tics in three patients |
| 16229000 | 2006 | Case series (safety) | Mov Disord | Syncope in four children with Tourette syndrome treated with guanfacine, probably from hypotension or bradycardia |
| 23473832 | 2013 | Review | Eur J Paediatr Neurol | Pharmacological options for Tourette syndrome with comorbid ADHD |
Australia Market Information
| ARTG Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| ARTG 11440D | Intuniv | Tablet 3 mg (as hydrochloride) | Not stated in the data compiled for this report |
Safety Considerations
Contraindications and conditions of concern (from knowledge graph drug-disease links, not product label text): orthostatic hypotension and other hypotensive disorders, multiple system atrophy, postural orthostatic tachycardia syndrome, atrioventricular block and heart block, myocardial infarction, coronary artery disease, cerebrovascular disorder, chronic kidney disease and end-stage renal failure, liver disease, gallbladder disease, anxiety and neurotic disorders, dysthymic disorder, constipation, and haemoglobinopathy.
Drug interactions (100 interactions recorded; the main ones listed):
- Major: aprepitant, dexamethasone, clarithromycin
- Moderate (examples): corticosteroids (hydrocortisone, prednisone, prednisolone, budesonide, betamethasone, triamcinolone), metformin, SGLT2 inhibitors (canagliflozin, dapagliflozin, empagliflozin, ertugliflozin), cimetidine, miconazole, cannabinoids (dronabinol, nabilone)
Safety signals in the literature:
- Syncope in children with Tourette syndrome treated with guanfacine (PMID 16229000)
- Secondary mania in children (PMID 10467976, 9730081, 27228067), relevant to patients with mood disorder risk
- Sinus pause in a combined olanzapine and guanfacine overdose (PMID 31447925)
Please refer to the TGA-approved Product Information (PI) for official warnings and contraindications, as label text was not available.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Tourette syndrome has a completed Phase 3 placebo-controlled trial and a Phase 4 study, and guanfacine is referenced in guideline-level literature. However, both trials are small (n=35 and n=34), and systematic reviews note limited overall evidence quality for tic drugs. The other nine predictions (including the top-scoring faciodigitogenital syndrome, chondromyxoid fibroma, and variably protease-sensitive prionopathy) lack evidence and should remain on Hold. Migraine and “specific developmental disorder” are research questions only.
To proceed, the following is needed:
- The TGA Product Information, to confirm warnings, contraindications and the approved indications for Intuniv (the licence record is blank), which also resolves a blocking safety data gap
- Mechanism of action data from DrugBank
- Confirmation of effect sizes from larger, adequately powered controlled trials in Tourette syndrome
- A monitoring plan covering blood pressure, heart rate, sedation and syncope, with a caution against abrupt discontinuation
- Screening for cardiac conduction disorders, hypotension and mood disorder history, and review of interacting medicines (particularly CYP3A4 inhibitors such as clarithromycin)
- Confirmation of whether any ANZCTR-registered trials exist
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.