Thyroid and Antithyroid Drugs

Question 1

Levothyroxine (t4, Synthroid)

Chemical Classification

Answer 1

Levoisomer of thyroxine

Question 2

Levothyroxine (t4, Synthroid)

Mechanism of Action

Answer 2

Increases metabolic rate; controls protein synthesis; increases cardiac output, renal blood flow, O2 consumption, body temp, blood volume, growth, development at cellular level via action on thyroid hormone receptors

Question 3

Levothyroxine (t4, Synthroid)

Uses

Answer 3

Hypothyroidism, myxedema coma, thyroid hormone replacement, thyrotoxicosis, congenital hypothyroidism, some types of thyroid cancer, pituitary TSH suppression

Question 4

Levothyroxine (t4, Synthroid)

Contraindications

Answer 4

Adrenal insufficiency, recent MI, thyrotoxicosis, hypersensitivity to beef, alcohol intolerance (inj only)
Obesity treatment

Question 5

Levothyroxine (t4, Synthroid)

Side Effects

Answer 5

CNS: Anxiety, Insomnia, Tremors, headache, THYROID STORM, excitability
CV: Tachycardia, Palpitations, Angina, Dysrhythmias, hypertension, CARDIAC ARREST
GI: nausea, diarrhea, increased or decreased appetite, cramps
MISC: Menstrual irregularities, weight loss, sweating, heat intolerance, fever, alopecia, decreased bone mineral density

Question 6

Levothyroxine (t4, Synthroid)

Nursing Considerations

Answer 6

ASSESS:

• BP, pulse periodically during treatment
• Weight daily in same clothing, using same scale, at same time of day
• Height, growth rate of child
• T3,T4, FTIs, which are decreased; radioimmunoassay of TSH, which is increased; radio uptake, which is increased if patient receiving too low a dose of medication
• PT may require decreased anticoagulant; check for bleeding, bruising
• Increased nervousness, excitability, irritability, which may indicate too high a dose of medication, usually after 1-3 wk of treatment
• Cardiac Status: angina, palpitation, chest pain, change in VS

PERFORM/PROVIDE
-Withdrawal of medication 4 wk before RAIU test

Question 7

Propylthiouracil

Functional Classification

Answer 7

Thyroid hormone antagonist (antithyroid)

Question 8

Propylthiouracil

Chemical Classification

Answer 8

Thioamide

Question 9

Propylthiouracil

Mechanism of Action

Answer 9

Blocks synthesis peripherally of T3, T4 (triiodothyronine, thyroxine), inhibits organification of iodine

Question 10

Propylthiouracil

Uses

Answer 10

Preparation for thyroidectomy, thyrotoxic crisis, hyperthyroidism, thyroid storm

Question 11

Propylthiouracil

Contraindications

Answer 11

Pregnancy (D), breastfeeding, hypersensitivity, agranulocytosis, hepatitis, jaundice

Question 12

Propylthiouracil

Side Effects

Answer 12

CNS: Drowsiness, Headache, Vertigo, Fever, paresthesias, neuritis
GI: Nausea, Diarrhea, Vomiting, JAUNDICE, HEPATITIS, loss of taste, LIVER FAILURE, DEATH
GU: NEPHRITIS
HEMA: AGRANULOCYTOSIS, LEUKOPENIA, THROMBOCYTOPENIA, HYPOTHROMBINEMIA, LYMPHADENOPATHY, bleeding, vasculitis, periarteritis
INTEG: Rash, Urticaria, Pruritus, Alopecia, Hyperpigmentation, lupuslike syndrome
MS: myalgia, arthralgia, nocturnal muscle cramps, osteoporosis

Question 13

Propylthiouracil

Nursing Considerations

Answer 13

ASSESS:

• HYPERTHYROIDISM: weight loss, nervousness, insomnia, fever, diaphoresis, tremors; HYPOTHYROIDISM: constipation, dry skin, weakness, headache
• Pulse, BP, temp
• I&O ratio; check for edema: puffy hands, feet, periorbits; indicates hypothyroidism
• Weight daily; same clothing, scale, time of day
• T3,T4, which are increased; serum TSH, which is decreased; free thyroxine index, which is increased if dosage is too low; discontinue product 3-4wk before RAIU
• BLOOD DYSCRASIAS: CBC with differential; leukopenia, thrombocytopenia, agranulocytosis
• OVERDOSE: peripheral edema, heat intolerance, diaphoresis, palpitations, dysrhythmias, severe tachycardia, increased temp, delirium, CNS irritability
• HYPERSENSITIVITY: rash, enlarged cervical lymph nodes; product may have to be discontinued
• HYPOPROTHROMBINEMIA: bleeding petechiae, ecchymosis
• Clinical response: after 3wk should include increased weight, pulse; decreased T4
• BONE MARROW SUPPRESSION: sore throat fever, fatigue
• HEPATOTOXICITY: LFTs before, during treatment; jaundice, nausea, vomiting, abdominal pain, anorexia diarrhea, fatigue

PERFORM/PROVIDE:
-Fluids 3-4L/day unless contraindicated

Question 14

Levothyroxine (t4, Synthroid)

Functional Classification

Answer 14

Thyroid Hormone