Pharm Block 2 (Thyroid Gland)

  1. What are the Two Thyroid hormones?
    Which has the longer half life? Stronger acting?
    Thyroxine (T4) and Triiodothyronine (T3)

    • T4 has a longer half life
    • T3 4X more potent
  2. What is Graves disease?
    What is Hashimoto's
    - Hyperthyroidism- It is an autoimmune disease--> excess in Thyroid hormones

    - Hypothyroidism
  3. What are the Clinical Features of :


    • - Heat intolerance
    • - Tachycardia
    • - Tremors
    • - increased basal metabolic rate
    • ____________________________
    • - Cold intolerance
    • - Bradycardia
    • - Decreased Deep tendon reflex
    • - increased cholesterol
  4. How is Thyroxine metabolized?
    What does it?
    difference between inner and outer ring?
    It is Deiodinated

    By 5'-monodeiodinase

    • Inner ring --> inactive reverse T3
    • Outer ring--> active T3
  5. What inhibits 5'-monodeiodinase?
    What does this do?
    • beta blockers
    • High does propylthiouracil
    • steroids

    prevents the conversion of T4 to T3
  6. From the Blood, what is the mechanism of Thyroid hormones?
    • -T4 dissociate from thyroxine binding globulin in plasma before entry into cells.
    • -In the cells, T4 is enzymatically deiodinated to T3 which enters nucleus and attaches to specific receptors which promotes protein synthesis.-->
    • action
  7. What converts I- to Thyroglobulin?
    What inhibits it?
    • - Peroxidase and H2O2
    • - Iodides and Thioamides
  8. What enzyme prevents the release of T3/T4 from the Thyroid Follicle?
    Iodides inhibit the Proteolysis of the Conjugated Thyroglobin
  9. What drugs do the following:

    Inhibition of hormone synthesis?
    Blockade of hormone release?
    T4 to T3 inhibitors?

    What are anion inhibitors?
    • -Propylthiouracil and Methimazole.
    • -Iodides
    • -Ipodates

    -They prevent the uptake of Iodine into the thyroid follicle. They are TOXIC
  10. Name the ANTI-thyroid Thioamides

    What do they do?
    Which is more potent?
    How soon till it works?
    Which do you use in pregnancy?
    Other uses ?
    Propylthiouracil, Methimazole

    • they inhibit Peroxidase
    • Methimazole is more potent so it can be used once a day.
    • Works in about 3 weeks. this is because the Thyroid Follicle has alot of Thyroid hormones stored.

    • - Propylthiouracil, is safe for use during pregnancy.
    • - Can be used in Prep for Surgery (decrease size of tumor)
  11. What are some adverse effects of Thioamides?
    • -maculopapular rash, arthralgia and vasculitis.
    • -Agranulocytosis – reversible.
    • -Hepatitis
  12. What is Potassium Iodide?
    What does it do?
    What are some uses?
    Is it slow acting?
    is it used long term?
    It is an Anti-thyroid Drug. an Inorganic iodide

    • It Blocks the organification and release through inhibition of Proteolysis
    • It decrease the size and vascularity – used before surgery preoperatively. and in thyroid storm treatment.
    • -It is Fast Acting
    • -It is not for long term as gland ‘escapes’ from its effect.
  13. What are some adverse effects of
    Potassium iodide?
    -Chronic use in pregnancy-->fetal goiter.

    -Iodine induced thyrotoxicosis (Jod Basedow’s phenomenon) at low doses.

    -salivary gland inflammation and acne.
  14. What is Radioactive Iodine?
    What is its mechanism?
    What is a 100% side effect?

    When is this treatment contraindicated?
    -It is a I-131 isotope is used in treatment of thyrotoxicosis and cancer while others are used in diagnosis.

    • - Given to patients--> Thyroid cells take it up--> in about 1-3 months -->emission of beta rays which destroys the thyroid gland. (IRREVERSIBLE)
    • - Patients become Hypothyroid (treat with replacement theropy).

    _Contraindicated in Pregnant Women
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Pharm Block 2 (Thyroid Gland)
Pharm Block 2 (Thyroid Gland)