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guanfacine (Oral route)

Pronunciation

GWAHN-fa-seen

Commonly used brand name(s)

In the U.S.

  • Intuniv
  • Tenex

Available Dosage Forms:

  • Tablet
  • Tablet, Extended Release

Therapeutic Class: Antihypertensive

Pharmacologic Class: Alpha-2 Adrenergic Agonist

Uses For guanfacine

Guanfacine is used to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

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Guanfacine works by controlling the nerve impulses along certain nerve pathways. As a result, it relaxes the blood vessels so that blood passes through them more easily. This helps to lower blood pressure.

Guanfacine is also used alone or together with other medicines to treat attention deficit hyperactivity disorder (ADHD). It works in the treatment of ADHD by increasing attention and decreasing restlessness in children and adults who are overactive, cannot concentrate for very long, or are easily distracted and impulsive. guanfacine is used as part of a total treatment program that also includes social, educational, and psychological treatment.

guanfacine is available only with your doctor's prescription.

Before Using guanfacine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For guanfacine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to guanfacine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of guanfacine tablets in children younger than 12 years of age. Safety and efficacy have not been established.

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of guanfacine extended-release tablets in children. However, safety and efficacy have not been established in children younger than 6 years of age.

Geriatric

Appropriate studies on the relationship of age to the effects of guanfacine have not been performed in the geriatric population. However, no geriatric-specific problems have been documented to date.

Pregnancy

Pregnancy Category Explanation
All Trimesters B Animal studies have revealed no evidence of harm to the fetus, however, there are no adequate studies in pregnant women OR animal studies have shown an adverse effect, but adequate studies in pregnant women have failed to demonstrate a risk to the fetus.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking guanfacine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using guanfacine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Yohimbine

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Other Medical Problems

The presence of other medical problems may affect the use of guanfacine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Bradycardia (slow heart rate), history of or
  • Dehydration or
  • Heart attack, recent or
  • Heart block, history of or
  • Heart or blood vessel disease, history of or
  • Hypotension (low blood pressure), history of or
  • Stroke, history of or
  • Syncope (fainting), history of—Use with caution. May make these conditions worse.
  • Kidney disease or
  • Liver disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.
  • Mental depression—Guanfacine may cause mental depression.

Proper Use of guanfacine

Take guanfacine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

guanfacine should come with patient information insert. Read and follow these instructions carefully. Ask your doctor if you have any questions.

If you are using guanfacine for high blood pressure:

  • In addition to the use of the medicine your doctor has prescribed, treatment for your high blood pressure may include weight control and care in the types of foods you eat, especially foods high in sodium (salt). Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.
  • Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
  • Remember that guanfacine will not cure your high blood pressure but it does help control it. Therefore, you must continue to use it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life. If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.

Take your daily dose of guanfacine at bedtime. (If you are taking more than one dose a day, take your last dose at bedtime). Taking it this way will help lessen daytime drowsiness.

Swallow the extended-release tablet whole with water, milk, or other liquids. Do not break, crush, or chew it.

You should not take the extended-release tablets with high fat meals.

Do not eat grapefruit or drink grapefruit juice while you are using guanfacine. Grapefruit and grapefruit juice may change the amount of guanfacine that is absorbed in the body.

Dosing

The dose of guanfacine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of guanfacine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For high blood pressure:
      • Adults—At first, 1 milligram (mg) once a day at bedtime. Your doctor may gradually increase your dose up to 3 mg a day, as needed.
      • Children—Use and dose must be determined by your doctor.
  • For oral dosage form (extended-release tablets):
    • For attention deficit hyperactivity disorder (ADHD):
      • Adults, teenagers, and children 6 years of age and older—At first, 1 milligram (mg) once a day, either in the morning or evening. Your doctor may gradually adjust your dose as needed. However, the dose is usually not more than 4 mg per day.
      • Children younger than 6 years of age—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of guanfacine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

If you miss taking guanfacine extended-release tablets for two or more days in a row, check with your doctor. If your body suddenly goes without guanfacine, some unwanted effects may occur. If you have any questions about this, check with your doctor.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using guanfacine

Your doctor should check you or your child's progress at regular visits to make sure guanfacine is working properly and to decide if you or your child should continue to take it.

You or your child will also need to have your blood pressure and heart rate measured before starting guanfacine and while you or your child are using it. If you notice any change to you or your child's recommended blood pressure or heart rate, call your doctor right away. If you have questions about this, talk to your doctor.

Do not stop taking guanfacine without checking first with your doctor. Your doctor may want you to gradually reduce the amount you or your child are taking before stopping it completely.

Make sure that you have enough guanfacine on hand to last through weekends, holidays, and vacations. You should not miss any doses. You may want to ask your doctor for another written prescription for guanfacine to carry in your wallet or purse. You can then have it filled if you run out when you are away from home.

Before having any kind of surgery (including dental surgery) or emergency treatment, tell the medical doctor or dentist in charge that you are using guanfacine.

Guanfacine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds, sedatives, tranquilizers, or sleeping medicine, prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you or your child are using guanfacine.

Guanfacine may cause some people to become dizzy, drowsy, faint, lightheaded, or less alert than they are normally. Make sure you know how you react to guanfacine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. Also, standing up slowly when getting up from a lying or sitting position may also help.

Guanfacine may cause dryness of the mouth, nose, and throat. For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if dry mouth continues for more than 2 weeks, check with your physician or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.

guanfacine Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common
  • Blurred vision
  • confusion
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • sweating
  • unusual tiredness or weakness
Less common
  • Chest pain or discomfort
  • cough
  • difficulty with breathing
  • fast, slow, or irregular heartbeat
  • increased need to urinate
  • lightheadedness, dizziness, or fainting
  • mental depression
  • noisy breathing
  • passing urine more often
  • pounding heartbeat
  • tightness in the chest

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose
  • Dizziness (extreme) or faintness
  • unusual tiredness or weakness (severe)

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Constipation
  • dizziness
  • drowsiness
  • dryness of the mouth
  • headache
  • irritability
  • nausea
  • sleepiness or unusual drowsiness
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • upper abdominal or stomach pain
  • vomiting
  • weight gain
Less common
  • Acid or sour stomach
  • belching
  • decreased appetite
  • decreased sexual ability
  • dry, itching, or burning eyes
  • heartburn
  • indigestion
  • lack or loss of strength
  • paleness of the skin
  • stomach discomfort, upset, or pain
  • trouble with sleeping

After you stop using guanfacine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:

  • Anxiety or tenseness
  • increased salivation
  • nervousness or restlessness
  • shaking or trembling of the hands and fingers
  • stomach cramps
  • sweating

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

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