Thyroid Drugs

Question 1

Thyroid hormone preparations

Answer 1

Levothyroxine
Liothyronine
Liotrix
Thyroid desiccated

Question 2

Thyroid hormone preparations - MoA

Answer 2

Binds to receptors causing increased gene transcription that leads to increased levels of proteins for growth, development, heat production.

Question 3

Thyroid hormone preparations - Contraindications

Answer 3

Lithium: inhibit release of thyroid hormones

Amiodarone: cause either hyper/hypothyroidsm

Question 4

Levothyroxine - Classification

Answer 4

Synthetic T4

Question 5

Levothyroxine - MoA

Answer 5

Converted to T3 in tissues, effects from both thyroid hormones

Question 6

Levothyroxine - Clinical use

Answer 6

Hypothyroidism (DOC).
TSH suppression in thyroid nodules, diffuse goiters, thyroid cancer (DOC).
Myxedema coma (IV)

Question 7

Levothyroxine - Adverse effects

Answer 7

Hyperthyroidism in high doses

Question 8

Levothyroxine - Interactions

Answer 8

Aluminum hydroxide, Ca2+-supplements, cholestyramine, ferrous sulfate, sucralfate decrease absorption.

Coffee, soy, dietary fiber: reduced absorption

Increased TSH:levothyroxine not sufficinent.

Question 9

Liothyronine - Classification

Answer 9

Synthetic T3

Question 10

Liothyronine - MoA

Answer 10

Does not increase plasma T4 –> difficult to monitor response to treatment.

Question 11

Liotrix - Classification

Answer 11

T4+T3 (4:1)

Question 12

Thyroid desiccated - Classifiaction

Answer 12

Natural pig T4+T3

Question 13

Antithyroid agents

Answer 13

Thioamide drugs:
Methimazole
Propylthiouracil
β-adrenoceptor antagonists
Iodide salts 
RAI

Question 14

Antithyroid agents - Clinical use

Answer 14

Hyperthyroidism

Question 15

Thioamide drugs - MoA

Answer 15

Inhibit synthesis of thyroid hormones by inhibition thyroperoxidase-catalysed steps.

Inhibition of hormone synthesis and depletion of glandular stores.

Question 16

Thioamide drugs - Clinical use

Answer 16

Graves disease: induce remission or control symptoms before surgery/RAI.

Question 17

When do you need to check for agranulocytosis in the case of thioamide drugs?

Answer 17

In case of fever, malaise, sore throat, flulike-symptoms

Question 18

Thioamide drugs - Adverse effects

Answer 18

Relapse (esp pt with thyroid-stimulating antibodies)
Pruritic maculopapular rash, arthralgia, fever.
Lupus erythematosus-like syndrome, hepatitis, GI distress.
Transient leukopenia, agranulocytosis.
Liver injury, fatal liver failure
Cross-sensitivity

Question 19

Which thioamide drug is contraindicated during pregnancy because of birth defects?

Answer 19

Methimazole

Question 20

Methimazole - Adverse effects

Answer 20

Birth defects

Question 21

Propylthiouracil - MoA

Answer 21

Also inhibit conversion of T4 –>T3 in peripheral tissue.

Question 22

Propylthiouracil - Clinical use

Answer 22

DOC just before and during 1st trimester

Question 23

Propylthiouracil - Adverse effects

Answer 23

Increased incidence of liver failure

Question 24

β-adrenoceptor antagonists

Answer 24

Propanolol

Question 25

β-adrenoceptor antagonists - MoA

Answer 25

inhibit conversion of T4 -->T3 | Reduce cardiovascular stimulation ass with hyperthyroidism (arrhythmias, palpitations, tachycardia)

Question 26

β-adrenoceptor antagonists - Clinical use

Answer 26

``` Severe thyrotoxicosis (thyroid storm) Symptomatic (control cardiovascular symptoms) in hyperthyroidism before surgery/RAI treatment. ```

Question 27

Iodide salts

Answer 27

Potassium iodine | Sodium iodine

Question 28

Iodide salts - MoA

Answer 28

Inhibit release of thyroid hormones

Question 29

Iodide salts - Clinical use

Answer 29

After RAI to inhibit radioactive thyroid hormone release.

Question 30

Iodide salts - Adverse effects

Answer 30

Skin rashes, hypersensitivity reactions, salivary gland swelling, metallic taste, sore gums, GI discomfort

Question 31

Iodide salts - Contraindications

Answer 31

Should not be used before RAI treatment because nonradioactive iodide compete with I for uptake by the thyroid gland. Pregnancy

Question 32

Thyrotropin alfa - Classification

Answer 32

Recombinant human thyrotropin

Question 33

Thyrotropin alfa - Clinical use

Answer 33

Increase thyroid gland uptake of RAI in diagnosis and treatment of thyroid conditions

Question 34

What happens if you start Levothyroxine treatment with too high dose?

Answer 34

Cardiovascular stress

Question 35

Sodium iodine - Contraindication

Answer 35

Pretreatment with thioamide drugs and pregnancy