The active ingredient in Tenex is guanfacine hydrochloride. According to the FDA monograph, guanfacine stimulates receptors in the central nervous system that reduce nerve signals controlling blood vessels. This causes the blood vessels to relax, lowering blood pressure. The pharmacologic effect also slows heart rate in some patients, which is why Tenex can cause bradycardia or lightheadedness.

Follow all directions given to you by your doctor and read all documents provided, including the full Prescribing Information, FDA-Approved Product Labeling, Instructions for Use, and Medication Guide before using Tenex. However, the following is a synopsis of the general guidelines for the use of Tenex:

• Tenex tablets should be taken once daily, usually at bedtime, or as directed.
• Tablets should be swallowed whole with water.
• If you miss a dose, take it when you remember, unless it is close to your next dose. Skip the missed dose if needed. Do not take two doses at the same time.
• Do not stop Tenex suddenly because blood pressure may rise quickly.
• Use Tenex only as directed; do not switch between immediate-release guanfacine and guanfacine extended-release tablets without medical advice, because they are not the same.
• Tenex may cause drowsiness, so caution is needed when driving or using machines. Children and older adults may be more sensitive to blood pressure changes and sleepiness. Drinking alcohol while on this medication can increase drowsiness and CNS-depressant effects.

Some mild or common side effects of Tenex seen in clinical trials as compared to placebo include:

• Drowsiness or sleepiness.
• Dry mouth.
• Tiredness or fatigue.
• Constipation.
• Abdominal pain.
• Lightheadedness or low blood pressure.
• Slow heart rate.
• Stomach pain or abdominal discomfort.
• Blurred vision.

Some individuals may experience serious side effects while using Tenex. These side effects may require immediate medical attention. If you experience any of the following, contact your healthcare provider or seek emergency medical help:

• Chest pain or signs of a heart attack (pain radiating to the neck, arms, or jaw).
• Fainting, severe low heart rate (bradycardia), or irregular heartbeat.
• Sudden drop in blood pressure causing dizziness, especially when standing (orthostatic hypotension).
• Trouble breathing, swelling, or symptoms of allergic reaction.
• Severe tiredness or confusion.

These are not all of the possible side effects of guanfacine. You should always seek medical advice from your healthcare provider for any questions or concerns about your medical condition or treatment. Read all patient information, medication guides, or drug information sheets that come with this medication. You can also report adverse effects to the Food and Drug Administration at www.fda.gov/medwatch or 1-800-FDA-1088.

Before starting Tenex, it is crucial to discuss any existing health conditions with your healthcare provider. You should be sure that your healthcare provider is aware of all your medical conditions, including if you have:

• Heart disease, slow heart rate, or low blood pressure.
• A history of fainting or cardiovascular problems.
• Kidney disease or liver problems.
• A history of depression or central nervous system conditions.
• If you are breastfeeding or planning to breastfeed.
• If you drink alcohol, as it increases drowsiness and CNS-depressant effects.

Tenex should not be used in patients who have had a hypersensitivity reaction to guanfacine hydrochloride or any of the ingredients in the formulation.

In general, medications used to lower blood pressure begin to work within hours, but full effects may take days.

When Tenex is taken with other prescription drugs, over-the-counter medications, vitamins, and supplements, it may change how they work or increase the frequency or severity of side effects. Make sure that you tell your healthcare professional about anything that you are taking to avoid any negative drug interactions, including:

• Barbiturates such as phenobarbital may increase sedation.
• Other CNS depressants, including alcohol, can increase drowsiness.
• Other antihypertensive medications may enhance blood pressure-lowering effects.
• Ketoconazole may raise blood levels of guanfacine and increase side effects.
• Over-the-counter medicines for colds, allergies, or sleep may interact due to sedative or blood pressure effects.
• Clonidine should not be substituted for guanfacine without medical guidance, as withdrawal effects may occur.

Tenex is supplied as immediate-release guanfacine tablets in strengths of 1 mg and 2 mg.

It should be stored at room temperature away from the reach of children or pets.

It is manufactured by PATHEON.

Yes, it is available from several manufacturers of generic drugs, and as an extended-release tablet under the brand name Intuniv.

Do not stop Tenex suddenly, because blood pressure may rise sharply. Your healthcare provider will help you slowly decrease the dose of guanfacine to avoid withdrawal effects.

Talk to your doctor if you are already pregnant or if you have any plans to become pregnant. They will know or recommend what is best for you.

It is not known whether guanfacine passes into breast milk.

Talk to your doctor if you are already breastfeeding or if you have any plans to breastfeed. They will know or recommend what is best for you.