ISONIAZID

Brand & Generic Names

INH	PMS Isoniazid
Isotamine	Rifamate
Laniazid	Rimifon
Nydrazid	Tubizid

Basic Information

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

Uses

Kills tuberculosis germs.

Dosage & Usage Information

How to take:
Tablet--Swallow with liquid to lessen stomach irritation.
Syrup--Follow label directions.

When to take:
At the same time each day.

If you forget a dose:
Take as soon as you remember up to 12 hours late. If more than 12 hours, wait for next scheduled dose (don't double this dose).

What drug does:
Interferes with TB germ metabolism. Eventually destroys the germ.

Time lapse before drug works:
3 to 6 months. You may need to take drug as long as 2 years.

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

Overdose

SYMPTOMS:
Difficult breathing, convulsions, coma.

WHAT TO DO:

• Dial 911 (emergency) or O (operator) for an ambulance or medical help. Then give first aid immediately.
• If patient is unconscious and not breathing, give mouth-to- mouth breathing. If there is no heartbeat, use cardiac massage and mouth-to-mouth breathing (CPR). Don't try to make patient vomit. If you can't get help quickly, take patient to nearest emergency facility.
• See EMERGENCY Information.

Possible Adverse Reactions or Side Effects

Life-threatening:

In case of overdose, see Overdose section.

Common:

• Muscle pain and pain in joints, tingling or numbness in extremities, jaundice.
• Confusion, unsteady walk.

Infrequent:

• Swollen glands, nausea, indigestion, diarrhea, vomiting, appetite loss.
• Dizziness.

Rare:

• Rash, fever, impaired vision, anemia with fatigue, weakness, fever, sore throat, unusual bleeding or bruising.
• Breast enlargement or discomfort.

Warnings & Precautions

Don't take if:
You are allergic to isoniazid.

Before you start, consult your doctor:

• If you plan to become pregnant within medication period.
• If you are allergic to athionamide, pyrazinamide or nicotinic acid.
• If you drink alcohol.
• If you have liver or kidney disease.
• If you have epilepsy, diabetes or lupus.

Over age 60:
Adverse reactions and side effects, especially jaundice, may be more frequent and severe than in younger persons. Kidneys may be less efficient.

Pregnancy:
No proven harm to unborn child. Avoid if possible, especially in the first 6 months of pregnancy. Consult doctor about use in last 3 months.

Breast-feeding:
Drug passes into milk. Avoid drug or discontinue nursing until you finish medicine. Consult doctor for advice on maintaining milk supply.

Infants & children:
Use only under medical supervision.

Prolonged use:

• Numbness and tingling of hands and feet.
• Talk to your doctor about the need for follow-up medical examinations or laboratory studies to check liver function, eyes.

Skin & sunlight:
No problems expected.

Driving, piloting or hazardous work:
Avoid if you feel dizzy. Otherwise, no problems expected.

Discontinuing:
Don't discontinue without doctor's advice until you complete prescribed dose, even though symptoms diminish or disappear.

Others:

• Diabetic patients may have false blood-sugar tests.
• Periodic liver-function tests and laboratory blood studies recommended.
• Prescription for vitamin B-6 (pyridoxine) recommended to prevent nerve damage.

Possible Interaction with Other Drugs

GENERIC NAME	COMBINED EFFECT
------------------------	-----------------------
Acetaminophen	Increased risk of liver damage.
(aluminum-containing)	Decreased absorption of isoniazid.
Anticholinergics*	May increase pressure within
	eyeball.
Anticoagulants*	Increased anticoagulant effect.
Antidiabetics*	Increased antidiabetic effect.
Antihypertensives*	Increased antihypertensive effect.
Carbamazepine	Increased risk of liver damage.
Cycloserine	Increased risk of central nervous
	system effects.
Didanosine	Increased risk of peripheral neuropathy.
Disulfiram	Increased effect of disulfiram.
Laxatives*	Decreased absorption and effect of
	isoniazid.
Hepatotoxics*	Increased risk of liver damage.
Ketoconazole	Increased risk of liver damage.
Narcotics*	Increased narcotic effect.
Niacin	Decreased niacin effect.
Phenytoin	Increased phenytoin effect.
Pyridoxine	Decreased chance of
(Vitamin B-6)	nerve damage in extremities.
Rifampin	Increased isoniazid toxicity to
	liver.
Sedatives*	Increased sedative effect.
Stimulants*	Increased stimulant effect.

Possible Interaction with Other Substances

INTERACTS WITH	COMBINED EFFECT
---------------	---------------
Alcohol:	Increased incidence of liver
	disease.
Beverages:	None expected.
Cocaine:	None expected.
Fish or Cheshire	Red or itching skin, fast heartbeat.
cheese, fish.	Seek emergency treatment.
Marijuana:	No interactions expected, but
	marijuana may slow body's recovery.
Tobacco:	No interactions expected, but
	tobacco may slow body's recovery.