Levothyroxine Sodium (Thyroid Hormone)

Question 1

What are the brand names of levothyroxine sodium?

Answer 1

Synthroid, Levoxyl, Levothroid

Question 2

What strength tablets are available of Levothroid?

Answer 2

25mcg, 50mcg, 75mcg, 88mcg, 100mcg, 112mcg, 125mcg, 137mcg, 150mcg, 175mcg, 200mcg, 300mcg

Question 3

What strength injection is available for levothyroxine sodium?

Answer 3

200 µg and 500 µg per vial (following reconstitution)

Question 4

What is the dosage equivalent of levothyroxine sodium?

Answer 4

0.1 mg L-Thyroxine equals approximately 65 mg thyroid, desiccated.

Question 5

The FDA approved indications for levothyroxine sodium?

Answer 5

Replacement therapy for increased or absent thyroid function of any etiology, myxedema coma or stupor.

Question 6

What are the dosages of levothyroxine sodium when being used to treat hypothyroidism?

Answer 6

0-1 years: 9mcg/kg/day
1-5 years: 6mcg/kg/day
6-10 years: 4mcg/kg/day
11-20 years: 3mcg/kg/day
Adults: 25-300mcg PO QD.

Question 7

What dose of levothyroxine sodium is used to treat myxedema coma or stupor?

Answer 7

200 to 500 µg intravenously on the first day. Get 100 and 300 µg intravenously on the second day. Get 50 to 100 µg intravenously on subsequent days. Do not add to other intravenous fluids.

Question 8

What should be monitored when a patient is taking levothyroxine sodium?

Answer 8

Thyroid stimulating hormone

Question 9

What is the mechanism of action of levothyroxine sodium?

Answer 9

The exact mechanism of action for L-thyroxine is unknown author is thought to be due to protein synthesis control.

Question 10

What are the drug interactions of levothyroxine sodium?

Answer 10

• May increase the effects of oral anticoagulants.
• Cholestyramine may decrease the absorption of levothyroxine.
• May decrease the effectiveness of digitalis glycosides.

Question 11

What are the contraindications of levothyroxine sodium?

Answer 11

• Relatively contraindicated in patients with diagnosed but as yet uncorrected adrenocortical insufficiency, untreated thyrotoxicosis, and the patients with acute myocardial infection.
• Not for the treatment of obesity or for weight loss.
• Use with caution in nursing mothers, and patients with cardiovascular disorders, hypopituitaryism, or diabetes, and in patients currently taking oral anticoagulants.
• Pregnancy Category A

Question 12

What are the adverse effects of levothyroxine sodium?

Answer 12

• Adverse effects other than those indicative of overdosage are rare.
• Overdosage can result in hyper-metabolic states resembling those of endogenous origin. Effects include fever, hyperglycemia, heart failure, fluid loss, tachycardia, anxiety, and insomnia.

Question 13

What should the pharmacist tell the patient when counseling them on the use of levothyroxine sodium?

Answer 13

• Do not discontinue therapy without first consulting a physician.
• Take on an empty stomach, one hour before or two hours following a meal.
• Notify physician if signs of hyperthyroidism occurs.
• Transient loss of hair may be seen in children, but recovery usually occurs.
• If a dose is missed, take it as soon as possible unless it is closer to your next dose than the missed us.