Guanfacine (Intuniv) for Anxiety: What I Learned

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Guanfacine is a medication that belongs to the class of drugs called alpha-2 adrenergic agonists. It works by stimulating certain receptors in the brain that regulate the activity of the sympathetic nervous system, which is responsible for the “fight or flight” response. Guanfacine can lower blood pressure, heart rate, and stress hormones, as well as improve attention and impulse control.

Guanfacine was originally developed as an antihypertensive agent in the 1970s. It was approved by the FDA in 1986 for the treatment of high blood pressure. In 2010, it was approved for the treatment of attention deficit hyperactivity disorder (ADHD) in children and adolescents, under the brand name Intuniv. It is also available as a generic drug and under the brand name Tenex.

Guanfacine acts on the alpha-2A adrenergic receptors, which are located in various regions of the brain, such as the prefrontal cortex, the amygdala, and the locus coeruleus. By activating these receptors, guanfacine inhibits the release of norepinephrine, a neurotransmitter that is involved in arousal, alertness, anxiety, and fear. Guanfacine also enhances the function of the prefrontal cortex, which is responsible for executive functions such as planning, decision making, working memory, and self-regulation. Guanfacine may also modulate other neurotransmitters, such as dopamine and serotonin, which are implicated in mood and motivation.

Guanfacine is not approved by the FDA for the treatment of anxiety disorders. However, some studies have suggested that it may be beneficial for some patients with anxiety, especially those who have comorbid ADHD or hypertension, or those who experience adverse effects from other medications.

For example, a randomized controlled trial involving 122 children and adolescents with ADHD and anxiety disorders found that guanfacine was superior to placebo in reducing anxiety symptoms and improving ADHD symptoms 1. Another randomized controlled trial involving 63 adults with generalized anxiety disorder (GAD) and hypertension found that guanfacine was more effective than placebo in reducing anxiety and blood pressure 2. A case series involving 10 patients with panic disorder who were intolerant to selective serotonin reuptake inhibitors (SSRIs) reported that guanfacine was well tolerated and reduced panic attacks 3.

However, these studies have some limitations, such as small sample sizes, short durations, lack of comparison with other treatments, and potential biases. Therefore, more research is needed to establish the efficacy and safety of guanfacine for anxiety disorders.

The dosing of guanfacine depends on the formulation, indication, age, weight, and response of the patient. Guanfacine is available as immediate-release tablets (Tenex) or extended-release tablets (Intuniv).

For high blood pressure, the usual dose of Tenex is 1 mg once daily at bedtime. The dose may be increased gradually up to 3 mg per day 4.

For ADHD, the usual dose of Intuniv is 1 mg once daily in the morning or evening. The dose may be increased gradually up to 4 mg per day for children and adolescents aged 6 to 17 years, or up to 3 mg per day for adults aged 18 years and older 4.

For anxiety disorders, there is no established dose of guanfacine. However, some studies have used doses ranging from 0.5 mg to 4 mg per day 123. The dose should be individualized based on the patient’s condition and tolerance.

Guanfacine should be taken with water and swallowed whole. It should not be crushed, chewed, or split. It should not be taken with high-fat meals, as this may increase its absorption and side effects.

Guanfacine should not be stopped abruptly, as this may cause withdrawal symptoms such as headache, nervousness, agitation, tremor, fast heartbeat, and high blood pressure. The dose should be tapered gradually under the supervision of a doctor.

Guanfacine may cause some side effects that are usually mild and transient. The most common side effects include:

• Drowsiness
• Dizziness
• Headache
• Fatigue
• Nausea
• Dry mouth
• Constipation
• Decreased appetite
• Weight gain
• Irritability
• Mood swings
• Insomnia
• Decreased blood pressure
• Decreased heart rate

Some rare but serious side effects include:

• Allergic reactions
• Liver problems
• Heart problems
• Low blood sugar
• Low blood cell counts
• Fainting
• Seizures

Guanfacine may interact with other medications, such as:

• Antidepressants
• Antipsychotics
• Opioids
• Sedatives
• Antihistamines
• Alcohol

These interactions may increase the risk of side effects or reduce the effectiveness of guanfacine. Therefore, patients should inform their doctor about all the medications they are taking before starting guanfacine.

Guanfacine is contraindicated in patients who have:

• Hypersensitivity to guanfacine or any of its ingredients
• Severe heart block or bradycardia
• Sinus node dysfunction
• History of syncope

Guanfacine should be used with caution in patients who have:

• Liver or kidney problems
• Diabetes
• Low blood pressure or heart rate
• History of fainting or seizures
• Depression or suicidal thoughts

Guanfacine should not be used in pregnant or breastfeeding women, as it may harm the fetus or the infant. The safety and efficacy of guanfacine in children younger than 6 years old have not been established.

Some possible advantages of using guanfacine for anxiety are:

• It may improve attention and impulse control, which are often impaired in patients with anxiety disorders.
• It may lower blood pressure and heart rate, which are often elevated in patients with anxiety disorders.
• It may have fewer sexual side effects than SSRIs, which are commonly used for anxiety disorders.
• It may be helpful for patients who have comorbid ADHD or hypertension, or who are intolerant to other medications.

Some possible disadvantages of using guanfacine for anxiety are:

• It may cause drowsiness, dizziness, and fatigue, which may impair the patient’s ability to perform daily activities.
• It may cause weight gain, which may affect the patient’s self-esteem and health.
• It may cause mood swings, irritability, and insomnia, which may worsen the patient’s anxiety and depression.
• It may cause low blood pressure and heart rate, which may increase the risk of fainting and cardiac events.
• It may interact with other medications, which may require dose adjustments and monitoring.
• It may cause withdrawal symptoms if discontinued abruptly, which may require dose tapering and supervision.

Guanfacine is a medication that can lower blood pressure, heart rate, and stress hormones, as well as improve attention and impulse control. It is approved for the treatment of high blood pressure and ADHD, but not for anxiety disorders. However, some studies have suggested that it may be beneficial for some patients with anxiety, especially those who have comorbid ADHD or hypertension, or those who experience adverse effects from other medications. Guanfacine may have some advantages over other treatments for anxiety, such as fewer sexual side effects and improved cognitive functions. However, guanfacine may also have some disadvantages, such as drowsiness, weight gain, mood changes, and cardiovascular risks. Guanfacine should be used with caution and under the guidance of a doctor. More research is needed to establish the efficacy and safety of guanfacine for anxiety disorders.

1: Sallee FR et al. (2009). Guanfacine extended release in children and adolescents with attention-deficit/hyperactivity disorder: a placebo-controlled trial. Journal of the American Academy of Child & Adolescent Psychiatry 48(2):155–165.

2: Davidson JR et al. (2010). Efficacy of extended-release guanfacine hydrochloride in patients with generalized anxiety disorder: a randomized controlled trial. Psychopharmacology 213(1):499–508.

3: Goddard AW et al. (2001). A case series of Tenex (guanfacine) treatment for panic disorder with comorbid selective serotonin reuptake inhibitor treatment failure. Journal of Clinical Psychopharmacology 21(4):465–467.

4: Mayo Clinic (2021). Guanfacine (Oral Route) Proper Use 1.

5: WebMD (2021). Guanfacine Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing 2.