Med of the Month: Guanfacine

September means new classrooms, new schedules, and, for many families, renewed attention to the medications that help students manage the school day. ADHD is especially common among school-age children and adolescents. According to the CDC, an estimated 7 million U.S. children ages 3 to 17, or 11.7%, currently have an ADHD diagnosis.

That makes guanfacine an especially timely medication to recognize. Unlike many of the medications commonly associated with ADHD, guanfacine is not a stimulant. It was originally used as an antihypertensive, while the extended-release formulation, Intuniv®, is FDA-approved for the treatment of ADHD, either on its own or alongside a stimulant. For dental professionals, its effects on blood pressure, heart rate, alertness, and salivary flow make it worth recognizing when it appears on a patient's medication list.

Generic Name: Guanfacine

Brand Name(s): Intuniv®, Tenex®

Pronunciation: GWAHN fa seen

About Guanfacine:

• Guanfacine is a centrally acting alpha_2A-adrenergic receptor agonist used to treat hypertension.

• The Intuniv brand of this medication is used to treat ADHD.

• This medication is also used off-label to treat opioid withdrawal, migraine headache prophylaxis, and Tourette syndrome.

Dentistry-related tidbits:

If you're treating a patient taking guanfacine, a few considerations are worth keeping in mind:

Local Anesthetic Warnings: 

Monitor blood pressure and heart rate when administering the following local anesthetics to a patient taking guanfacine, as the combination may increase the risk of hypotension and bradycardia:

• Articaine (Septocaine, Ultracan, Ultacan Forte, Articadent Dental with Epinephrine, Orabloc)

• Bupivacaine (Marcaine, Sensorcaine)

• Lidocaine (Xylocaine)

• Mepivacaine (Carbocaine, Polocaine)

• Ropivacaine (Naropin)

When administering a local anesthetic containing epinephrine, monitor the patient's blood pressure, as the combination with guanfacine may increase blood pressure. If needed, consider limiting the Epinephrine dose to 0.04 mg in adults or the following:

• 1 cartridge of anesthetic containing 1:50,000 Epinephrine

• 2 cartridges of anesthetic containing 1:100,000 Epinephrine

• 4 cartridges of anesthetic containing 1:200,000 Epinephrine

Oral Manifestations: 

• Guanfacine may cause xerostomia. Consider prescribing a fluoride supplement and increasing the frequency of dental exams.

• Guanfacine may also cause changes in taste.

Treatment Considerations:

• Guanfacine may cause significant lightheadedness, dizziness, and hypotension, particularly in elderly patients. Before dismissing the patient, have them sit upright in the dental chair for a few minutes to reduce the risk of lightheadedness or a fall. Assist the patient when getting out of the chair and, when appropriate, while walking through the office.

Staying Safe: important interactions to be aware of

Using a tool like MedAssent DDS Rx Check can help support safe prescribing and identify clinically relevant interactions.

Some of the most clinically important interactions with guanfacine include:

• Steroids, NSAIDs, aspirin, and aspirin-containing products may decrease the antihypertensive efficacy of guanfacine.

• Narcotics, benzodiazepines, muscle relaxants, and other sedating medications may have additive effects with guanfacine, increasing the risk of severe CNS and/or respiratory depression and diminished psychomotor function.

• Anticonvulsants such as gabapentin, pregabalin, and carbamazepine may increase the risk of respiratory and CNS depression and diminished psychomotor function. Carbamazepine may also decrease guanfacine levels and efficacy, and increase the risk of PR interval prolongation, AV block, and bradycardia.

Fun facts:

• Guanfacine was a blood pressure medication before it was an ADHD medication. Guanfacine's initial U.S. approval dates back to 1986, while Intuniv®, the extended-release formulation developed for ADHD, received FDA approval in 2009.

• Despite its use for ADHD, guanfacine is not a CNS stimulant and Intuniv® is not a controlled substance. The FDA labeling states that it has no known potential for abuse or dependence.

• Abrupt discontinuation of guanfacine can cause clinically significant rebound hypertension, which is why the medication should generally be tapered rather than stopped abruptly.

• Immediate-release and extended-release guanfacine have different pharmacokinetic profiles, so the FDA specifically advises against substituting one for the other on a milligram-for-milligram basis.

Get more dental-specific drug information with the Digital Drug Handbook (web) or BrushUp Rx (mobile app).