Drugs for thyroid disorders Flashcards
what are the thyroid agents
levothryoxine (T4)
liothyronin (T3)
Liotrix
Thyroid Desiccated
what are the antithyroid agents
Radiosctive iodine (131I)
potassium iodide
methimazole
propylthiouracil (PTU)
thyroid storm is also known as _ and _ and can be treated with?
thyrotoxicosis and symptomatic hyperthyroidism
propranolol
what is propranolol and what does it do?
it is a non-selective beta 1 and beta 2 blocker
it is used to reduce heart rate and tremor during a thyroid storm - its MOA is to inhibit the conversion of T4 to T3 in peripheral tissues
also may help to reduce systemic vascular resistance
why is propranolol preferred to other beta blockers in thyrotoxicosis/thyroid storm?
it blocks monodieiodinase type I and type II which stops the conversion of T4 to T3 (active)
it also inhibits the cardiovascular symptoms that occur in thyroid storm (termor, shakes, increased BP and pulse)
works at 2 levels
TSH is _ in primary hypothyroidism
TSH is _ or _ in secondary or tertiary hypothyroidism
high
normal or low
_ is the most sensitive screening test for hyperthyroidism and primary hypothyroidism
TSH
what is the thyroid receptor
a nuclear hormone receptor with a zinc finger DNA binding domain, ligand binding domain and 2 activation function domains
has alpha and beta subuits and is activated by thyroid hormones
ligand activating transcription factors - superfamily
TSH is also known as?
thyrotropin
describe thryoid hormone synthesis
thyroglobulin is iodinated at its tyrosine residues and is conjugated, eventuallly it is exocytosed and undergoes proteolysis to form T4 and T3
SCn and CIO4 both inhibit what step of thyroid hormone synthesis
thicyanate and perchlorate
they inhbit the uptake of iodide into the thyroid gland
iodide is transformed into iodine by what
peroxidase
what blocks iodine from being integrated into thyroglobulin
iodides and thioamides
what blocks the proteolysis step of thyroglobulin into T4 and T3
iodides
what blocks the peripheral conversion of T4 to T3 in tissues
radiocontrast, B blockers, corticosteroids, amiodarone
what is amiodrone?
what does it cause?
it is a commonly use anti-arrhythmic that is used to treat ventricular arrhythmia, atrical fibrillation ect.
it can cause type II amidodrone induced thyrotoxicosis which results from destruction of the thyroid tissue
you must get baseline levels of TSH, T3 and T4 to monitor for the emergence of hyperthroidism symptoms
each 200 mg tablet of amiodarone contains _ iodine and _ is released as free iodine. This means that the dosing is toxic/50 fold higher.
74.4mg
7.4mg
what is levothyroxine
L-thyroine
that is used to treat throid hormone deficinecy that is given in the T4 form
it is peripherally converted to T3 in the body and can take up to 6 weeks to work
side effects of levothyroxine and how is dosing measured
Side effects: weight loss, tremor, sweating, anxiety, trouble sleeping, fast heart rate
dosing is based on regular measurments of TSH and T4 in the patients blood
what drugs can impair levothyroxine absorption?
cholestyramine , antacids, iron etc.
what are the thioamides?
carbimazole
methimazole
propylthiouracil
carbimazole is converted to?
methimazole
which one is more potent : methimazole or PTU
methimazole
what is methimazole
this is an antithyroid drug that is used to treat graves disease
it blocks thyroid peroxideses which blocks iodide organification
it is taken before surgert to lower thyroid levels and minmize the effects of thyroid manipulation
side effects of methimazole
agranulocytosis, leukopenia, thrombocytopenia, liver inflammation
monitor people with preexisiting liver diease, with alcohol abuse, or hepatitis
what is PTU
this is an thioamide that blocks the synthesis of thyroid hormones by inhibiting the conversion of thyroxine to triiodethyronine
it is used in graves disease or in people with a toxic multinodular goiter
works only on endogenous throid hormones
can use if patient cant tolerate methimazole, can be used before surgery, can be used with radioactive iodine
potassium iodie is a stable form of _ that blocks _ uptake. It is used to treat _ and _
iodine
iodine uptake
hyperthyroidism and idodine def.
can be used along with outer anti-thyroid meds to prepare for surgery
potassium iodide is also used to protect the thyroid from _. it shrinks the gland and decreases thyroid hormone production
radiation
it DOES NOT AFFECT HEART RATE
what is radioactive iodine (I131)
this is a therapy for thyroid cancer that destroys the thyroid gland and the cancerous cells
category D in pregnancy- do not use
has little effect else where in the body
what beta blockers are used in graves diease and thyroid storm
what is the MOA
and which one is used more, which one has less cerebral effects
propranolol, metopropol, atenolol
stabalizes the membrane to inhbit T4 to T3 conversion and stops symtpoms of hyperthyroidism and also blocks Beta receptors to stop catecholamine release
propranolol used more
atenolol- less cerebral effects
what is perchlorate
this inhibits thryoid hormone production by being a competitive inhibitor of iodide uptake by the thyroid gland
- it blocks the sodium-iodie synmporter
- used to control amiodarone induced thyoid dysfunction
there is no effect on the iodination process
