Brand name:

Tenex

Pronounced: TEN-ex
Generic name: Guanfacine hydrochloride

Why is this drug prescribed?

Tenex is given to help control high blood pressure. This medication reduces nerve impulses to the heart and arteries; this slows the heartbeat, relaxes the blood vessels, and thus reduces blood pressure. Tenex may be given alone or in combination with other high blood pressure medications, especially thiazide diuretics, such as Diuril, Esidrix, or Naturetin.

Most important fact about this drug

You must take Tenex regularly for it to be effective. Since blood pressure declines gradually, it may be several weeks before you get the full benefit of Tenex; and you must continue taking it even if you are feeling well. Tenex does not cure high blood pressure; it merely keeps it under control.

How should you take this medication?

Take Tenex exactly as prescribed by your doctor--usually 1 dose per day. Tenex should be taken at bedtime, since it will probably cause drowsiness.

After 3 or 4 weeks, if your blood pressure is still too high, your doctor may raise the dosage of Tenex. In some cases, you may take 2 evenly spaced doses per day rather than a single dose at bedtime.

--If you miss a dose...

Take the forgotten dose as soon as you remember. This will help to keep the proper amount of medicine in your body. However, if it is almost time for the next dose, skip the one you missed and go back to your regular schedule. Never try to "catch up" by doubling the dose. If you miss taking Tenex for 2 or more days in a row, check with your doctor.

--Storage instructions...

Store Tenex at room temperature. Use the container it came in.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine whether it is safe for you to continue taking Tenex. This medication will probably make you drowsy, especially when you first begin to take it.

• More common side effects may include:
  Constipation, dizziness, dry mouth, fatigue, headache, impotence, sleepiness, weakness

• Less common or rare side effects may include:
  Abdominal pain, amnesia, breathing difficulties, chest pain, confusion, conjunctivitis (red, puffy eyes), decreased sex drive, depression, diarrhea, difficulty swallowing, fainting, heart palpitations, indigestion, insomnia, itching, leg cramps, malaise (vague feeling of being sick), mania and aggression (in patients with attention-deficit hyperactivity disorder), nausea, numbness or tingling of the skin, purplish spots on the skin, rash and peeling, ringing in the ears, "runny" nose, skin inflammation, slow heartbeat, stuffy nose, sweating, taste alterations, upset stomach, urinary incontinence, vision disturbance

Some of these side effects may lessen or disappear as your body gets used to Tenex.

Why should this drug not be prescribed?

Do not take Tenex if you are sensitive to it or have ever had an allergic reaction to it.

Tenex is not recommended for controlling the severe high blood pressure that accompanies toxemia of pregnancy (a disorder of pregnant women characterized by a rise in blood pressure, swelling, and leakage of protein into urine).

Special warnings about this medication

While taking Tenex, you should be monitored very closely by your doctor if you have any of the following medical conditions:

Chronic kidney or liver failure
Heart disease
History of stroke
Recent heart attack

Since Tenex causes drowsiness and may also make you dizzy, do not drive, climb, or perform hazardous tasks until you find out exactly how the medication affects you.

While taking Tenex, use alcoholic beverages with care; you may feel intoxicated after drinking only a small amount of alcohol.

If you have kidney damage and also take the antiseizure drug phenytoin (Dilantin), your body may process and eliminate Tenex rather quickly; in that case, you may need fairly frequent doses of Tenex to lower your blood pressure adequately.

If you have been taking Tenex for a while, do not stop taking it without consulting your doctor. Discontinuing abruptly may result in nervousness, rapid pulse, anxiety, heartbeat irregularities, and so-called rebound high blood pressure (higher than before you started taking Tenex). If you do have rebound high blood pressure, it will probably develop 2 to 4 days after your last dose of Tenex. Rebound high blood pressure, if it occurs, will usually diminish and then disappear over a period of 2 to 4 days.

Possible food and drug interactions when taking this medication

If Tenex is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Tenex with the following:

Barbiturates such as Amytal, Seconal, Tuinal, and others
Benzodiazepines such as Tranxene, Valium, Xanax, and others
Phenothiazines such as Mellaril, Stelazine, Thorazine, and others
Phenytoin (Dilantin)

Special information if you are pregnant or breastfeeding

If you are pregnant or plan to become pregnant, notify your doctor immediately. Tenex should be taken during pregnancy only if clearly needed. It is not known whether Tenex appears in breast milk. Check with your doctor if you plan to breastfeed.

Recommended dosage

ADULTS

CHILDREN

Overdosage

Any medication taken in excess can have serious consequences. If you suspect an overdose of Tenex, seek medical attention immediately.

• Symptoms of Tenex overdose may include:
  Drowsiness, lethargy, slowed heartbeat, very low blood pressure