Guanfacine
Guanfacine is a first line agent used for the treatment of tics in conditions such as Tourette’s syndrome and chronic tic disorders. Guanfacine is an Alpha 2 Adrenoceptor agonist that has also been used to treat conditions such as ADHD. It is suitable to treat children and adolescents 6-17 years of age in whom a stimulant is not suitable, not tolerated or ineffective.
Typical starting doses are 0.5mg at bedtime and then increasing slowly, on a weekly basis, to 1.5-2.0mg twice daily. Administration with high fat meals should be avoided (as this may increase absorption).
Caution should be applied if there is evidence of liver or kidney failure, bradycardia, heart block, history of cardiovascular disease or hypokalaemia.
Prior to prescribing, it is necessary to conduct a baseline evaluation to identify patients at increased risk of somnolence and sedation, hypotension and bradycardia, QT-prolongation arrhythmia and weight increase/risk of obesity. This evaluation should address a patient’s cardiovascular status including blood pressure and heart rate, documenting comprehensive history of concomitant medications, past and present co-morbid medical and psychiatric disorders or symptoms, family history of sudden cardiac/unexplained death.
Stopping medication should be tapered to minimise potential withdrawal effects.
Monitoring during titration
During dose titration, weekly monitoring for signs and symptoms of somnolence and sedation, hypotension and bradycardia should be performed.
Ongoing monitoring
During the first year of treatment, the patient should be assessed at least every 3 months for:
Signs and symptoms of:
- somnolence and sedation
- hypotension
- bradycardia
- weight increase/risk of obesity
It is recommended clinical judgement be exercised during this period. 6 monthly monitoring should follow thereafter, with more frequent monitoring following any dose adjustments (see section 4.4).
Table 1
Dose titration schedule for children aged 6-12 years | ||||
| Weight Group | Week 1 | Week 2 | Week 3 | Week 4 |
| 25 kg and up Max Dose= 4 mg | 1 mg | 2 mg | 3 mg | 4 mg |
Table 2
Dose titration schedule for adolescents (aged 13-17 Years) | |||||||
| Weight Groupa | Week 1 | Week 2 | Week 3 | Week 4 | Week 5 | Week 6 | Week 7 |
| 34-41.4 kg Max Dose= 4 mg | 1 mg | 2 mg | 3 mg | 4 mg | |||
| 41.5-49.4 kg Max Dose= 5 mg | 1 mg | 2 mg | 3 mg | 4 mg | 5 mg | ||
| 49.5-58.4 kg Max Dose= 6 mg | 1 mg | 2 mg | 3 mg | 4 mg | 5 mg | 6 mg | |
| 58.5 kg and above Max Dose= 7 mg | 1 mg | 2 mg | 3 mg | 4 mg | 5 mg | 6 mg | 7 mgb |
a Adolescent subjects must weigh at least 34 kg. b Adolescents weighing 58.5 kg and above may be titrated to a 7 mg/day dose after the subject has completed a minimum of 1 week of therapy on a 6 mg/day dose and the physician has performed a thorough review of the subject’s tolerability and efficacy. | |||||||
The physician who elects to use guanfacine for extended periods (over 12 months) should re-evaluate the usefulness of guanfacine every 3 months for the first year and then at least yearly based on clinical judgement (see section 4.4), and consider trial periods off medication to assess the patient’s functioning without pharmacotherapy, preferably during times of school holidays.
The complete drug information can be accessed through the summary of product characteristics
