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Drugs acting on the Thyroid glad
Pharm II - Block III
12
Pharmacology
Not Applicable
07/17/2010

Additional Pharmacology Flashcards

 


 

Cards

Term
What 3 hormones does the thyroid gland secreat
Definition

1.Thyroxine- T4
2.Triiodothyronine-T3
3.Calcitonin - Calcitonin produced by C-cells and important in calcium metabolism

Term

How are T3 and T4 synthesised?

Where are they stored?

What is this known as?

Definition

Thyrosine residues + Iodine = monoiodotyrosine (MIT)
2I + Thyrosine = dioiodotyrosine (DIT)
DIT + MIT= T3
2 x DIT= T4
Stored in thyroglobulins in the interior of the follicle - known as coupling

Term
How is T4 conversion to T3 in the peripheral inhibited?
Definition

Propylthiouracil - especially in the Liver & Kidney

by blocking - 5'deiodinase

Term
What are the possible thyroid abnormalities?
Definition

1.Hypothyroidism
2.Hyperthyroidism

Term
How is Hypothyroidism treated?
Definition

In hypothyroidism you give synthetic T3 & T4


T4 –Thyroxine sodium - given orally in the mornings
T3-Liothyronine - injectable form - given in emergency cases when an immediate response is required i.e myxodema coma

 

Term
How is Hyperthyroidism treated?
Definition

Hyperthyroidism can be due to thyroid gland tumor which hypersecretes thyroid hormone. 1.drugs inhibiting the thyroid hormone synthesis and 2.drugs which destroy the tumors should be given

1.Inhibit hormone synthesis: (antithyroid drugs) Propylthiouracil, Methimazole, Carbimazole
2.Inhibit hormone release: Iodine
3.Destroy thyroid tissues: Radioactive Iodine 131I
4. Give B blockers

 

Term

Name the antithyroid drugs aka thioamines

MOA?

When are they used?

Definition

Propylthiouricil

Methimazole

Carbimazole

 

Inhibits peroxidase and prevents oxidation of Iodine leading to

1.Inhibition of iodination of tyrosine residues (thus no MIT or DIT)

2.Inhibition of coupling of iodotyrosine to form T3 and T4

No action on iodine trapping and peripheral

conversion of T4 to T3 (except propylthiouracil)

 

-Hyperthyroidism

Term
What special MOA does Propylthiouracil have?
Definition

Iodine trapping and peripheral

conversion of T4 to T3


Term

Radioactive iodine (131I)

What is its MOA

When is it used?

Definition

- 131I is concentrated by thyroid,
- incorporated in colloid,
- Emits X-rays and b-particles (rays) from within the follicle,
- causing self distruction self destruction.

Used in:
Toxic nodular goiter
Grave’s disease

Term
Why are B blockers given in hyperthyroidism?
Definition

Beta blockers are used to mask the sympathetic
over activity associated with hyperthyroidism
No effect on synthesis or release of thyroid
hormones 

 

Term
Which antithyroid drug aka thioamide is safe to use in pregnancy?
Definition
Propylthiouracil as it is highly protein bound
Term
What is used in thyrotoxicities?
Definition
IODIDE - pre-operativley to decrease the gland size & vascularity
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