ANTITHYROID DRUGS

Brand & Generic Names

METHIMAZOLE
PROPYLTHIOURACIL
Propyl-Thyracil
Tapazole
Thiamazole

Basic Information

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

Uses

• Treatment of overactive thyroid (hyperthyroidism).
• Treatment of angina in patients who have overactive thyroid.

Dosage & Usage Information

How to take:
Tablet--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:
At the same times each day.

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:
Prevents thyroid gland from producing excess thyroid hormone.

Time lapse before drug works:
10 to 20 days.

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

Overdose

SYMPTOMS:
Bleeding, spots on skin, jaundice (yellow eyes and skin), loss of consciousness.

WHAT TO DO:

Overdose unlikely to threaten life. If person takes much larger amount than prescribed, call doctor, poison-control center or hospital emergency room for instructions.

Possible Adverse Reactions or Side Effects

Life-threatening:

In case of overdose, see Overdose section.

Common:

Skin rash, itching, dryness.

Infrequent:

Dizziness, taste loss, sore throat with chills and fever, abdominal pain, constipation, diarrhea.

Rare:

Headache; enlarged lymph glands; irregular or rapid heartbeat; unusual bruising or bleeding; backache; numbness or tingling in toes, fingers or face; joint pain; muscle aches; menstrual irregularities; jaundice; tired, weak, sleepy, listless; swollen eyes or feet; black stools; excessive cold feeling; puffy skin; irritability.

Warnings & Precautions

Don't take if:
You are allergic to antithyroid medicines.

Before you start, consult your doctor:

• If you have liver disease.
• If you have blood disease.
• If you have an infection.
• If you take anticoagulants.

Over age 60:
Adverse reactions and side effects may be more frequent and severe than in younger persons.

Pregnancy:
Risk to unborn child outweighs drug benefits. Don't use.

Breast-feeding:
Drug filters into milk. May harm child. Don't use.

Infants & children:
Use only under special medical supervision by experienced clinician.

Prolonged use:

• Adverse reactions and side effects more common.
• Talk to your doctor about the need for follow-up medical examinations or laboratory studies to check thyroid function, complete blood counts (white blood cell count, platelet count, red blood cell count, hemoglobin, hematocrit).

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, such as antihistamines, tranquilizers, sedatives, pain medicine, narcotics and mind-altering drugs.

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.

Others:
No problems expected.

Possible Interaction with Other Drugs

GENERIC NAME	COMBINED EFFECT
------------------------	-----------------------
Amiodorone	Decreased antithyroid effect.
Anticoagulants*	Increased effect of anticoagulants.
Antineoplastic	Increased chance to
drugs*	suppress bone marrow.
Chloramphenicol	Increased chance to suppress bone
	marrow.
Clozapine	Toxic effect on bone marrow.
Digitalis glycosides*	Increased digitalis effect.
Iodinated glycerol	Decreased antithyroid effect.
Iodine	Decreased antithyroid effect.
Levamisole	Increased risk of bone marrow
	depression.
Lithium	Decreased thyroid activity.
Potassium iodide	Decreased antithyroid effect.
Thioguanine	More likelihood of toxicity of both
	drugs.
Tiopronin	Increased risk of toxicity to bone
	marrow.

Possible Interaction with Other Substances

INTERACTS WITH	COMBINED EFFECT
---------------	---------------
Alcohol:	Increased possibility of liver
	toxicity. Avoid.
Beverages:	No problems expected.
Cocaine:	Increased toxicity potential of
	medicines. Avoid.
Foods:	No problems expected.
Marijuana:	Increased rapid or irregular
	heartbeat. Avoid.
Tobacco:	Increased chance of rapid
	heartbeat. Avoid.