Guanfacine

💊 What is Guanfacine used for?

• •Attention deficit hyperactivity disorder (ADHD), used alone or as an add-on to stimulant medicines
• •The label says it is not known if it is safe and effective in children younger than 6 years old

How it works

The label describes guanfacine as a central alpha 2A-adrenergic receptor agonist. The sections provided do not explain in more detail how it works.

How it is usually taken

• •Taken once a day, in the morning or in the evening, at about the same time each day
• •Swallowed whole with a small amount of water, milk, or other liquid
• •Do not crush, chew, or break the tablets
• •Do not take it with a high-fat meal
• •May be taken alone or with an ADHD stimulant medicine, as your doctor directs
• •Your doctor will check your blood pressure and heart rate during treatment

Comes as

• •1 mg extended-release tablets (white to off-white, round). The description section also mentions 2 mg, 3 mg, and 4 mg strengths.

⚠️ Guanfacine side effects

🛑 Who should not take Guanfacine, and who should be careful

The label says not to take it if

• 🚨You are allergic to guanfacine or any of the ingredients in the tablet
• 🚨You have had a hypersensitivity (allergic-type) reaction to guanfacine extended-release tablets, their inactive ingredients, or other products containing guanfacine

Tell your doctor before taking it if

• •Tell your doctor if you have heart problems or a low heart rate
• •Tell your doctor if you have fainted
• •Tell your doctor if you have low or high blood pressure
• •Tell your doctor if you have liver or kidney problems or any other medical condition
• •Tell your doctor if you are pregnant or plan to become pregnant
• •Tell your doctor if you are breastfeeding or plan to breastfeed
• •Tell your doctor about all medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements
• •Avoid becoming dehydrated or overheated, which may raise the chance of low blood pressure or fainting

🔀 Guanfacine with other medicines, food and alcohol

The label says to discuss these with your doctor or pharmacist

• •Ketoconazole and other strong or moderate CYP3A4 inhibitors, such as fluconazole. The label says these can raise guanfacine levels in the body.
• •Strong or moderate CYP3A4 inducers, such as rifampin and efavirenz. The label says these can lower guanfacine levels.
• •High blood pressure medicines
• •Sedatives, benzodiazepines, barbiturates, and other medicines that cause sleepiness or dizziness
• •Antipsychotics
• •Other sympatholytic drugs, which may worsen slow heart rhythm problems
• •Alcohol, which may make sleepiness or dizziness worse

Alcohol and food

The label does not say.

🤰 Guanfacine in pregnancy and breastfeeding

Pregnancy

The patient leaflet says it is not known if this medicine will harm an unborn baby, so talk to your doctor if you are pregnant or plan to become pregnant. The label says guanfacine has been used in pregnant women for decades without a drug-associated risk of major birth defects, miscarriage, or adverse outcomes identified, but use in pregnancy has been infrequent. In animal studies, no harm to the fetus was seen at 3 to 4 times the maximum recommended human dose, while higher doses were linked to reduced fetal survival and maternal toxicity.

Breastfeeding

The label says it is not known if guanfacine passes into breast milk. Talk to your doctor about the best way to feed your baby while taking this medicine.

🗓️ Storage, missed doses and taking too much

Storage

Store at 20°C to 25°C (68°F to 77°F). Temporary excursions between 15°C and 30°C (59°F to 86°F) are permitted, according to the label.

If a dose is missed

The label says to try not to miss a dose. If you miss a dose, take the next dose at your regular time. If you miss 2 or more doses, talk to your doctor, as you may need to restart the medicine at a lower dose. Do not take a double dose to make up for a missed one.

If too much is taken

Call Poison Control at 1-800-222-1222 or go to the nearest emergency room right away if you take too much. The label lists hypotension, drowsiness, lethargy, and slow heart rate as symptoms seen after overdose, and says high blood pressure may appear early, followed by low blood pressure. Pupil narrowing (miosis) may also be noted on examination.

🗒️ Questions to ask about Guanfacine

• How will you check my blood pressure and heart rate while I take this medicine?
• Should I take this medicine in the morning or the evening?
• Will this medicine be taken alone, or with my ADHD stimulant medicine?
• What should I do if I miss a dose or vomit and cannot take my dose?
• How will you lower my dose slowly if I need to stop this medicine?
• Are any of my other medicines, vitamins, or supplements likely to interact with this one?
• Is it safe for me to drive or operate machinery while I am adjusting to this medicine?

❓ Guanfacine: frequently asked questions