GUANFACINE

Brand & Generic Names

Tenex

Basic Information

• Habit forming? No
• Prescription needed? Yes
• Available as generic? No
• Drug class: Antihypertensive

Uses

Treats high blood pressure, usually in combination with a diuretic drug.

Dosage & Usage Information

How to take:
Tablets--Swallow with liquid or food to lessen stomach irritation. If you can't swallow whole, crumble tablet and take with liquid or food.

When to take:
Usually at bedtime.

If you forget a dose:
Take as soon as you remember up to 2 hours late. If more than 2 hours, wait for next scheduled dose (don't double this dose).

What drug does:
Decreases stimulating effects of the sympathetic nervous system on the heart, kidneys and arteries throughout the body.
Decreases both systolic and diastolic blood pressure.

Time lapse before drug works:
Within 1 week.

Don't take with:
Any other medicine without consulting your doctor or pharmacist.

Overdose

SYMPTOMS:
Difficulty breathing, loss of consciousness, dizziness, very slow heartbeat.

WHAT TO DO:

• Dial 911 (emergency) or O (operator) for an ambulance or medical help. Then give first aid immediately.
• See EMERGENCY Information.

Possible Adverse Reactions or Side Effects

Life-threatening:

Shortness of breath. Seek emergency treatment immediately.

Common:

• Decreased sexual function, drowsiness, constipation.
• Increased dental problems because of dry mouth and less salivation.

Infrequent:

• Confusion, dizziness or fainting, slow heartbeat.
• Mental depression, eye irritation, insomnia, tiredness or weakness, headache, nausea and/or vomiting.

Rare:

May occur if medicine is abruptly discontinued--Anxiety, chest pain, heartbeat irregularities, excess salivation, sleep problems, nervousness, sweating.

Warnings & Precautions

Don't take if:
You have had a recent heart attack.

Before you start, consult your doctor:

• If you have heart disease or liver disease.
• If you have coronary insufficiency.
• If you have mental depression.

Over age 60:
None expected.

Pregnancy:
No proven harm to unborn child, but avoid if possible.

Breast-feeding:
Effect not documented. Consult your doctor.

Infants & children:
Effect not documented. Consult your pediatrician.

Prolonged use:
Talk to your doctor about the need for follow-up medical examinations or laboratory studies to check blood pressure.

Skin & sunlight:
No problems expected.

Driving, piloting or hazardous work:
Don't drive or pilot aircraft until you learn how medicine affects you. Don't work around dangerous machinery. Don't climb ladders or work in high places. Danger increases if you drink alcohol or take medicine affecting alertness and reflexes.

Discontinuing:

• Don't discontinue without consulting doctor. Dose may require gradual reduction if you have taken drug for a long time. Doses of other drugs may also require adjustment.
• May occur if medicine is discontinued abruptly: anxiety, chest pain, heartbeat irregularities, excess salivation, sleep problems, nervousness, sweating.

Others:

• This medication works better if you attempt to reduce your weight to normal, exercise regularly, restrict salt in your diet and reduce stress wherever possible. Continue taking medicine even when you feel good.
• Adverse reactions are usually dose-related and diminish when dosage is reduced.

Possible Interaction with Other Drugs

GENERIC NAME	COMBINED EFFECT
------------------------	-----------------------
Antihypertensives,	May increase effects
other*	of guanfacine and other medicines.
Carteolol	Increased antihypertensive effect.
Central nervous	Increases depressant
system (CNS)	effect of both drugs.
Clozapine	Toxic effect on the central nervous
	system.
Estrogens*	May decrease antihypertensive
	effects of guanfacine.
Ethinamate	Dangerous increased effects of
	ethinamate. Avoid combining.
Fluoxetine	Increased depressant effects of
	both drugs.
Leucovorin	High alcohol content of leucovorin
	may cause adverse effects.
Lisinopril	Increased antihypertensive effect.
	Dosage of each may require
	adjustment.
Methyprylon	Increased sedative effect, perhaps
	to dangerous level. Avoid.
Nabilone	Greater depression of central
	nervous system.
Nicardipine	Blood-pressure drop. Dosages may
	require adjustment.
Nimodipine	Dangerous blood pressure drop.
Non-steroidal anti-	May decrease antihypertensive
inflammatory drugs	effects of guanfacine.
Propafenone	Increased effect of both drugs and
	increased risk of toxicity.
Sertraline	Increased depressive effects of
	both drugs.
Sotalol	Increased antihypertensive effect.
Sympathomimetics*	May decrease antihypertensive
	effects of guanfacine.
Terazosin	Decreases effectiveness of
	terazosin.

Possible Interaction with Other Substances

INTERACTS WITH	COMBINED EFFECT
---------------	---------------
Alcohol:	Excess use may lead to dangerous
	drop in blood pressure.
Any containing	May decrease anti-
caffeine, such as	hypertensive effect
coffee, tea or cocoa.	of guanfacine.
Cocaine:	Increased risk of heart block and
	high blood pressure.
Foods:	None expected.
Marijuana:	May decrease antihypertensive
	effect of guanfacine.
Tobacco:	May decrease antihypertensive
	effect of guanfacine.