Pharm Ch 31

Mechanism of action for Levothyroxine (Levoxyl, Levothroid, Synthroid)?

-Chemically pure 100% T4 which makes this drug more predictable. -Synthetic thyroid hormone. -Induces changes in metabolic rate (protein, carb, lipid) and to increase O2 consumption, temp, ect....

Mechanism of action for Propylthiouracil (PTU)?

-Impedes formation of thyroid hormone. -Inhibits the incorporation of iodine molecules into the amino acid tyrosine (required to make the precursors of T3 and T4) so the formation of the thyroid hormone is impeded. -Can also inhibit the conversion of T3 & T4 in the peripheral circulation, but cannot inactivate already-existing hormone.

Contraindications, interactions and cautions of Levothyroxine (Levoxyl, Levothroid, Synthroid)?

-Recent MI, adrenal insufficiency, hyperthyroidism. -Don't switch brands of medication freely, can destabalize treatment.

Primary Hypothyroidism

-Stems from abnormality in the thyroid gland itself and occurs when the gland is not able to perform one of its functions. -Most common type.

How long till you should see therapeutic effects of Propylthiouracil (PTU)?

2 weeks.

How long till you should see therapeutic effects of Levothyroxine (Levoxyl, Levothroid, Synthroid)?

3-4 weeks. Works best when taken in the morning.

Adverse effects of Levothyroxine (Levoxyl, Levothroid, Synthroid)?

Adverse effects from this drug are usually a result of overdose. Tachycardia, dysrhythmias, hypertension, nausea, GI upset, menstrual irregularities, weight loss, heat intolerance and fever.

Graves disease

Autoimmune disorder in which the patients own immune system attacks the thyroid gland, causing hyperthyroidism, most common in women over 20.

What should you avoid while on antithyroid drugs such as Propylthiouracil (PTU)?

Avoid foods high in iodine like fish and tofu!

Drug interactions of Levothyroxine (Levoxyl, Levothroid, Synthroid)?

Can decrease the efficacy of insulin and anti diabetic drugs (higher glucose levels.) Interacts with anticoagulants.

Myxedema

Cutaneous and dermal edema secondary to increased deposition of connective tissue components in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease Decreased metabolic rate. involves loss of mental/physical stamina, weight gain, hair loss, firm edema, yellow dullness of the skin.

Adverse effects of Propylthiouracil (PTU)?

Drowsiness, headache, vertigo, GI upset, SMOKY URINE, rash, myalgia, arthralgia, cramps, increse BUN, enlarged thyroid.

Goiter

Enlargement of the thyroid gland from overstimulation by elevated TSH levels. Happens because thee is little or no thyroid hormone in circulation.

Indications for Propylthiouracil (PTU)?

Hyperthyroidism

Indications for Levothyroxine (Levoxyl, Levothroid, Synthroid)?

Hypothyroidism

Route of Propylthiouracil (PTU)?

Oral only Avail in a 50 mg tab.

Contraindications, interactions and cautions of Propylthiouracil (PTU)?

Pregnancy D category! Do not use in pregnancy, however, sometimes used in low doses if necessary to treat the hyperthyroidism that can occur in pregnancy. Additive leukopenic effects when taken with other bone marrow suppressants. Enhances the effects of anticoagulants.

Cretinism

Sever lack of thyroid hormone Low metabolic rate and retarded growth, sexual development and possibly mental development.

If a patient is on Levothyroxine (Levoxyl, Levothroid, Synthroid) treatment and is experiencing symptoms of hypothyroidism (cold intolerance, depression, constipation, and dry skin) what should the nurse expect is wrong?

The patient is receiving an inadequate dose of medication.

What does the term "Euthyroid" mean?

Thyroid hormone levels are within normal limits.

What happens if you become pregnant while on Levothyroxine (Levoxyl, Levothroid, Synthroid) treatment?

You would continue treatment.