Thyroid drugs - Staudinger Flashcards
- levothyroxine (T4)
- liothyronine (T3)
- liotrix (4:1 ratio of T4:T3)
- thyroid dessicated
thyroid agents
- radioactive iodine
- potassium iodide
- methimazole
- PTU
anti-thyroid agents
what drug is widely used to reduce heart rate and tremor during a thyroid storm?
propranolol
- inhibits conversion of T4 to T3, which occurs in peripheral tissues
- may help reverse reduced systemic vascular resistance
what drug can cause type II thyrotoxicosis?
amiodarone
- occurs from actual thyroid tissue destruction
NOTE: pts started on amiodarone need baseline measures of TSH, free T3 and T4 (repeat every6-12 months)
commonly prescribed medication for arrhythmia
- both atrial and ventricular arrhythmias
amiodarone
what is the dosage of iodine in each 200mg tablet of amiodarone?
74.4mg of iodine, with 7.4mg (10%) per day being released as free iodine
what is the daily recommended iodine intake for adults?
0.15mg
what is the anti-thyroid drug used to treat hyperthyroidism?
methimazole
- thioamide group of medications - blocks iodide organification
- PTU
- methimazole
- carbimazole
thioamide group of medications
what medication inhibits the enzyme thyroperoxidase?
methimazole
- thioperoxidase catalyzes a necessary step in the synthesis of T3 and T4
- stable form of iodine
- blocks iodine uptake
- used as treatment for hyperthyroidism
- used as treatment for iodine deficiency
- used along with anti-thyroid medication to prepare thyroid gland for surgical removal
potassium iodide
- used to protect the thyroid from radiation exposure (shrinks thyroid gland, decreasing TH production)
- does not effect heart rate
- does not produce irregular heartbeat
potassium iodide
- patients with Graves disease
- pt with toxic multinodular goiter (intelerant of methimazole, surgery or radioactive iodine therapy is not appropriate tx option)
- used to relieve sx of hyperthyroidism
- used for prep of thyroidectomy
- used in radioactive iodine therapy in pts who are intolerant of methimazole
propothiouracil (PTU)
inhibits synthesis of thyroid hormones in hyperthyroidism
- inhibits conversion of thyroxine to T3 in peripheral tissues
- does not inactivate pre-existing T4 and T3
- does not interfere with effectiveness of thyroid hormones given by mouth or by injection
- may be an effective treatment for thyroid storm
PTU
- produced by the pituitary gland, in response to TRH from hypothalamus
- promotes growth of the thyroid gland
- stimulates production of thyroid hormones
TSH
- excessive thyroid hormones -> pituitary gland stops producing TSH
what is the most sensitive screening test for hyperthyroidism and primary hypothyroidism?
TSH
- if within normal limits, these diagnoses can be excluded
- used to treat hormone deficiency
- manufactured form of thyroid hormone -> T4
- converted to T3
- maximum effect can take up to six weeks
levothyroxine (L-thyroxine)
what are the side effects from excessive dosing of L-thyroxine
- weight loss
- heat intolerance
- sweating
- anxiety
- trouble sleeping
- tremor
- tachycardia
what is the highlighted drug that impairs levothyroxine absorption?
cholestramine
what therapy for thyroid cancer contraindicated in pregnancy women?
radioactive iodine
- thyroid gland absorbs iodine
- radiation destroys the thyroid gland
beta blocker with less cerebral effects than propranolol
- membrane-stabilizing action
- inhibits T4 to T3 conversion
- indicated in Graves disease and thyroid storm
atenolol
which beta blocker is the most widely studied and used in thyrotoxicosis?
propranolol
- inhibits thyroid hormone production
- competitive inhibitor of iodide uptake by thyroid gland
- blocks sodium-iodide symporter (NIS)
- no effect on iodination process
perchlorate-blocking agent
