Guanfacine is also used off-label to treat Tic Disorders, Anxiety Disorders and PTSD.An off-label use of guanfacine is for treatment of anxiety, such as generalized anxiety disorder and post-traumatic stress disorder symptoms. Guanfacine and other α2A agonists have anxiolytic-like action, thereby reducing the emotional responses of the amygdala, and strengthening prefrontal cortical regulation of emotion, action and thought. These actions arise from both inhibition of stress-induced catecholamine release, and from prominent, post-synaptic actions in prefrontal cortex. Due to its prolonged half-life, it also has been seen to improve sleep interrupted by nightmares in PTSD patients. All of these actions likely contribute to the relief of the hyperarousal, re-experiencing of memory, and impulsivity associated with PTSD. Guanfacine appears to be especially helpful in treating children who have been traumatized or abused. Adverse effects
Side effects of guanfacine are dose-dependent.Very common (>10% incidence) adverse effects include sleepiness, tiredness, headache, and stomach ache.Common (1-10% incidence) adverse effects include decreased appetite, nausea, dry mouth, urinary incontinence, and rashes.Typical side effects such as fatigue, irritability and stomach upset can take a week or two to subside. Increases in dosage can have the same adjustment period. Interactions
Guanfacine availability is significantly affected by the CYP3A4 and CYP3A5 enzymes. Medications that inhibit or induce those enzymes change the amount of guanfacine in circulation and thus its efficacy and rate of adverse effects. Because of its impact on the heart, it should be used with caution with other cardioactive drugs.
As such, metabolism by liver is the assumption for those with impaired renal function, as supported by increased frequency of known side effects of orthostatic hypotension and sedation. History
In 1986, guanfacine was approved by the FDA for the treatment of hypertension under the brand name Tenex (Drugs@FDA). In 2010, guanfacine was approved by the FDA for the treatment of attention deficit hyperactivity disorder for people 6–17 years old. It was approved for ADHD by the European Medicines Agency under the name Intuniv in 2015. It was added to the Australian Pharmaceutical Benefits Scheme for the treatment of ADHD in 2018. Brand names
Brand names include Tenex, Afken, Estulic, and Intuniv (an extended release formulation). Research
Guanfacine has been studied as a treatment for post-traumatic stress disorder (PTSD). Evidence of efficacy in adults is limited, but one study found positive results in children with comorbid ADHD. It may be also useful in adult PTSD patients who do not respond to SSRIs.Results of studies using guanfacine to treat Tourettes have been mixed.Guanfacine has been investigated for treatment of withdrawal for opioids, ethanol, and nicotine. Guanfacine has been shown to help reduce stress-induced craving of nicotine in smokers trying to quit, which may involve strengthening of prefrontal cortex meditated self-control. References
External links
"Guanfacine". Drug Information Portal. U.S. National Library of Medicine.