Thyroid and Antithyroid Drugs Flashcards
The endocrine system is made up of glands that secrete what?
Hormones
Hormones target what?
Receptor sites
True or False Hormones target receptor sites to regulate response to stress, growth metabolism & homeostasis
True
An endocrine disorder usually involves the over secretion or under secretion of what?
Hormones
What is the expected action of a thyroid hormone drug?
First, thyroid hormones are a synthetic form of thyroxine ( T4) a form of lioththyronine (T3) or a combination of both-that increase metabolism rate, protein synthesis, CO, renal perfusion , oxygen use, body temp, blood volume & growth processes
What is the name of a thyroid hormone?
Levothyroxine, also Liothyronine, Liotrix, & Thyroid USP
What are the therapeutic uses of a thyroid hormone? (5)
1) thyroid hormone replacement- hypothyroidism 2) Thyroid are used for the emergency tx of myxedema coma (IV route) 3) Cretinism 4) Simple goiter 5) Maintenance of thyroid hormone levels after surgery or radiation of the thyroid gland
What is Myxedema?
Severe hypothyroidism leading to decreased mental status * it is a medical emergency with a high mortality rate**
What are the routes of administration of a thyroid hormone?
Oral, IV for Myxedema
Complications or adverse effects of a thyroid hormone?
Over medication can lead to ***thyrotoxicosis- which is anxiety, tachycardia, CP, nervousness, tremors, palpitations, abdominal cramping, heat intolerance, fever, diaphoresis & weight loss
*** What are important nursing actions to teach about thyroid hormones ?
TSH & T4 levels should be monitored once a year, chronic overtreatment can cause A-FIB, and increased risk of FX from accelerated bone loss in older adults & teach clients to report bleeding-bruising & or petechiae. Last, it can take 6-8 weeks for full effect of Rx- Take the Rx on an empty stomach- 30-60 min before breakfast* medication is dosed in micrograms* Lifelong replacement id required.
What are contramanifestations or contraindications of a thyroid hormone?
Pregnancy risk A, pregnancy may require increased dosage, contraindicated in those with adrenal insufficiency, also because of the cardiac stimulant effects use is contraindicated after an MI, use cautiously in older adults & those with diabetes, CV, HTN, & ischemic heart disease- * not a tx for obesity
Drug Interactions of a thyroid hormone?
Increase cardiac responsiveness to catecholamines (epinephrine, dopamine, dobutamine) therefore increasing the risk of dysrhythmias, also binding agents, anti ulcer meds, Ca & Fe supplements, magnesium salts & foods reduce levothyroxine absorption, last many antiseizure & antidepressant medications can increase levothyroxine metabolism, can also increase requirements for insulin & digoxin, Levothyroxine can increase the anticoagulant effects of warfarin by breaking down Vit K
What drug class is Methimazole and Propylthiouracil ( PKU) ?
Thionamides
What is the pharmacological action of Methimazole ? (3)
1) Blocks the synthesis of thyroid hormones, 2) Prevents the oxidation of iodide 3) Blocks conversion of T4 into T3 (PKU)
What is oxidation?
It is a normal process that happens in our body. It can help fight pathogens, hence reduces the risk of infections
What are the therapeutic uses for Methimazole
Graves Disease, As an adjunct to irradiation of the thyroid gland, also after thyroid surgery it produces an euthyroid (a normally functioning thyroid) state prior to thyroid removal surgery
When is Propylthiouracil ( PKU) used?
During the first trimester because is causes less severe birth defects
What is the route of administration of Methimazole and Propylthiouracil (PKU) ?
Oral
What are complications of Thionamides?
Hypothyroidism, Agranulocytosis (which manifests as sore throat, fever) & Liver injury, hepatitis in propylthiouracil (PTU)
What is the treatment for Agranulocytosis?
Filgrastim (it is a leukocyte growth factor, to decrease the incidence of infection-which is manifest by febrile neutropenia
Contraindications/Precautions
Methimazole is contraindicated in pregnancy & lactation, Also use cautiously in clients who have bone marrow depression or immunosuppression & in clients who are at risk for liver failure.** Do not discontinue the medication abruptly due to a risk of thyroid crisis due to stress response ** Avoid consumption of shellfish, which contain Iodine do not take any OTC meds without consulting the provider.
