All you need to know about ADHD Medication /

Guanfacine: brand name Intuniv

01 In Brief

Guanfacine (gwan-fa-seen), is one of the non-stimulant medications used to treat Attention Deficit Hyperactvity Disorder in Australia. It is used in children and adolescents who do not repond to or have significant side effects from stimulant medication such as methylphenidate or dexamphetamine. It can also be used as an add on medication to stimulants to provide cover over 24 hours.

02 What Do I Need To Know?

Guanfacine has been used in the USA since 2010 and Europe since 2015. It's brand name is Intuniv.

 

Indications for use

The immediate release form of medication is used to treat high blood pressure and the extended release is used for ADHD symptoms.

 

It was funded in Australia by the PBS on a streamlined authority prescription in April 2019, for treatment of ADHD in children and adolescents aged 6-17 years as

-      Monotherapy (when stimulants or atomoxetine are not suitable, not tolerated or have been shown to be ineffective) 

-      Add on therapy to stimulants (where there has been a sub-optimal response to stimulants)

-      It must be used as part of a comprehensive ADHD management programme, typically including psychological, educational and social measures

Guanfacine may be considered in the following clinical situations:

-      Subset of ADHD patients who fail to respond to stimulant therapy

-      Subset of ADHD patients who have side effects that preclude use of stimulants such as insomnia or anorexia

-      Some children treated with stimulants, whose ADHD symptoms may not be adequately controlled in the hours before school or in the evening. Or children that require multiple doses if stimulants throughout the day

-      Comorbid conditions where the use of psychostimulants is limited e.g. anxiety, tics and oppositional defiance

-      Patients in whom stimulants and non stimulants i.e. atomoxetine are contraindicated

-      Doctors or parents prefer treatment with non stimulants

 

Guanfacine can decrease symptoms of hyperactivity, impulsivity, anxiety, irritability, temper tantrums, explosive anger, and tics.

The positive effects usually do not start for 2 weeks after a stable dose is reached. The full benefit may not be seen for 2–4 months.

How does it work?

Guanfacine is a central alpha 2A receptor agonist. Stimulation of these receptors in the prefrontal cortex of the brain mimics the neurotransmitter, noradrenalin actions in this region. Current ADHD theories demonstrate dysfunction of the noradrenalin transmitters as underlying the cognitive and behavioural manifestations of ADHD.

These receptors are thought to affect working memory, distraction, and attention and impulse control. It also affects other executive functioning such as emotional sensitivity, hyperarousal and social aggression.

Side effects

The commonest side effects are drowsiness, fatigue, decreased blood pressure, and a sedated state. Most children don’t have these side effects.

The side effects are more common at first or as the dose is increased. If the child is still sleepy in the daytime after 4 weeks on the same dose, a lower dose or a different medicine may be needed.

-       Daytime sleepiness, especially when bored or not doing anything (usually worst in the first 2–4 weeks).  Do not allow your child to drive, ride a bicycle or motorcycle, or operate machinery if this happens.

-       Fatigue or tiredness

-       Low blood pressure (rarely a serious problem)

-       Dizziness or light-headedness—This side effect is worse when the child stands up quickly, especially when getting out of bed in the morning; try having the child stand up slowly.

-       Headache

-       Stomach ache 

-       Nightmares in 5% that usually resolve in 2-4 weeks

Dosage table

Weight

Target dose 0.05- 0.12 mg/kg per day

25- 33.9 kg

2-3 mg per day

34- 41.4 kg

2-4 mg per day

41.5- 49.5 kg

3-5 mg per day

58.5- 91 kg

4-7 mg per day

>91 kg

5-7 mg per day

Dosage

It is a long acting medication and is taken once daily either at night or in the morning.

-      It should be taken at around the same time every day

-      Try giving it 30-45 minutes before bedtime

-      It is long acting and should be swallowed whole and not chewed or crushed

-      Do not administer with a high fat meal as it speeds up the release of the medication and increases absorption 

-      It lasts for 24 hours

It comes as 1mg, 2mg, 3mg and 4 mg modified release tablets. Each tablet is colour coded and has a 503 on one side and the dosage number on the other side.

It comes in packs of 28 = 4 blister packs of 7

 

Doses above 4mg per day have not been evaluated for children 6- 12 years

Doses above 7mg per day have not been evaluated for adolescents 13-17 years

 

Starting dose

Start with 1mg per day and increase as tolerated to target dose by 1mg increments every 4-7 days

Maintenance

The majority of children reach optimal target doses of 0.05 – 0.12 mg /kg per day.

Missed doses

Medication should not be stopped abruptly as rebound high blood pressure may occur.

If you miss a dose the night before give the missed dose the next morning the usual dose again that night.

If you miss 2 or more doses then may need to go back to a lower dose and gradually increase again. Contact your doctor to discuss.

Discontinuation of treatment

Patients may experience increase in heart rate and blood pressure when Intuniv is stopped. To avoid this decrease the dose in increment of no more than 1 mg every 3-7 days to minimise the risk.

Always have at least 2-3 weeks supply at home.

Interactions

Do not use with a drug, which is a CYP3A4 inhibitor or inducer (carbamazepine, rifampicin) including grapefruit juice. Ask your pharmacist.

03 What Others Say

American Psychiatric Association - Guanfacine

04 I Want To Know More

Therpeutic Goods Administartion; Australia Public Assessment Report for Gunafacine 

The information published here has been reviewed by Flourish Paediatrics and represents the available published literature at the time of review.
The information is not intended to take the place of medical advice.
Please seek advice from a qualified healthcare professional.
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Last updated: 26/10/2019