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Thyroid Flashcards

1
Q

Hyperthyroidism pharmacology?

A
  1. Anti-thyroid medication
  2. Iodine
  3. Radioactive idoine therapy
  4. Surgery
  5. Adjunct therapy: Propranolol , Ca2+ channel blockers and Glucocorticoids
  6. Thyroid Storm
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2
Q

Hypothyroidism pharmacology?

A
  1. Levothyroxine sodium(T4)
  2. Liothyroxine(T3)
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3
Q

Anti-thyroid medication ?

A

Carbimazole converted to an active metabolite methimazole

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4
Q

Carbimazole MOA?

A
  1. Decrease uptake & concentration of the inorganic iodine by the thyroid
  2. Decrease formation of di-iodotyrpsine & thyroxine

3.

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5
Q

Carbimazole conversion and effects on throid Hs

A

Once converted to Methimazole prevents thr thyroid peroxidase enzyme from coupling & iodinating the tyrosine residues on the thyroglobulin therefore decreasing the production of thyroid hormones(T2/4)J

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6
Q

Where is carbimazole not used and why?

A

Not used in inflammatory thyroid disease since the release of performed thyroid hormone is not inhibited

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7
Q

What is biosynthesis of T3 & T4

A

Dietary iodine(I) ingestion (Absorbed into bloods stream as iodide)
↓
Uptake of iodide(I-) by thyroid gland
↓
Synthesis of thyroglobulin(precursor of thyroid hormone
↓
Idodide(I-) oxidized into Iodine(I) by thyroid peroxidase (METHIMAZOLE)
↓
Iodination of thryoglobin tyrosine residues=Monoiodotyrosine(MIT) + Diiosotyrosine(DIT)
↓
Coupling of iodotyrosine residues(MIT & DIT) → T3/4

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8
Q

Carbimazole caution?

A

Pregnancy
-Relatively safe at doses < 20mg/day
-No breastfeeding
-Do not combine with thyroxine

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9
Q

Carbimazole DI?

A

Warfarin , Heparin

-Enhances anti-coagulant effect
-Adjust dosage to prothrombin time

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10
Q

Carbimazole A/E?

Uncommon(1)

&

Uncommon(4)

A

Common:
-Itching
-Skin rash

Uncommon:
-Agranulocytosis(Sore throat & fever)
-Cholestatic hepatitis
-Mild arthralgia
-Alopecia

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11
Q

Iodine drug?

A

Lugol’s solutions(Potassium Iodide)

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12
Q

Iodine/Lugol’s solutions(Potassium Iodide) MOA?

A
  1. ↓ Thyroglobulin proteolysis(Proteolytic processing) ∴ ↓ thyroid hormone secretion(T3/4)
  2. Temporary inhibition of iodine organification in the thyroid gland(Wolf-Chaikoff effect)
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13
Q

Wolf-Chaikoff effect?

A

Temporary inhibition of iodine organification in the thyroid gland

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14
Q

Wolf-Chaikoff effect after two-four weeks?

A

However, within two or four weeks of continual exposure to excess iodine organification and thyroid hormone biosynthesus resumes normally-Escape from the Wolff-Chaikoff effect)

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15
Q

Iodine effects of thyroid hormone?

A

↑ Iodine concentration inhibits thyroid hormone synthesis and release

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16
Q

Iodine caution(2)?

A
  1. Renal Impairement→Hyperkalemia
  2. Pregnancy→ Neonatal goiter
    →Neonatal hypothyroidism
    (No breastfeeding)
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17
Q

Iodine DI?

A

-ACE-Inhibitors
-K+-sparring diuretics

All cause K+ overload

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18
Q

Iodine A/E?

Common(2)
Less Common(4)
Prolonged use(4)

A

Common:
1. Gastric irritation ∴ taken with meals
2. Bloody diarrhoea

Less Common:
1. Arthralgia
2. Fever
3. Lymphadenopathy
4. Hypersensitivity

Prolonged use:
1. Metallic use
2. Conjunctivitis
3. Painful salivary glands
4. ↑ salivation

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19
Q

Iodine Indications?

A
  1. Preoperative preparation for thyroidectomy in Graves disease
    -Renders thyroid less vascular
  2. Thyroid Storm
    -Iodine blocks T4/T3 release within hours
  3. Adjunctive therapy to antithyroid agents in Graves disease
  4. Protective after radioioiodine therapy
    -Potassium iodidie blocks uptake of radioactive iodine isotopes by the thyroid glands thereby minimizing the risk of radiation-induced thyroid neoplasms
20
Q

Radioactive idoine therapy name?

A

Sodium iodide 131I -capsule

21
Q

Radioactive idoine therapy MOA?

A

Radioiodine-131 beta particles react with intracellular water in the thyroid gland to produce free radicals

-Destruction of the thyroid gland

22
Q

Radioactive iodine therapy Dosage?

A

First dose:
Symptoms improve after 2 weeks

Second dose:
Given 6-12 weeks later to prevent recurrence

23
Q

Radioactive iodine therapy CI?

A
  1. Pregnancy ∴ contraceptive advised for both treated men and women
  2. Paediatrics(not recommended)
  3. ↑Incidence of radiation-induced hypothyroidism
  4. Large toxic nodules goitres may require repeated doses
24
Q

Radioactive iodine therapy disadvantage/

A

↑Incidence of radiation-induced hypothyroidism

25
Radioactive iodine therapy A/E?
1. Painful radiation thyroiditis 2. Radiation-induced thyroiditis 3. Severe swelling
26
Radioactive iodine therapy indications?
1. Hyperthyroidism 2. Pre-operatively to reduce the vascularity of the gland 3. Post operatively in the case of carcinomas to reduce recurrence
27
Surgery
Total or partial removal of the thyroid gland & Removal of bones of the orbit for decompression in the thyroid optic neuropathy
28
Adjunct therapy?
1. Propranolol 2. Ca2+ channel blockers 3. Glucocorticoids
29
Propranolol
Indications: Relieves tachycardia, tremors, palpitations, anxiety , state and tension CI: Cardiac Failure
30
Ca2+ channel blockers effects(2)?
-Control tachycardia -↓Supraventricular tachyarrthymias
31
Glucocorticoids drug?
Prednisone
32
Thyroid storm?
Life-threatening exaggerated manifestations of hyperthyroidism * Hyperthermia *Severe cardiac failure *Possible cardiac failure *Severe agitation/mental disorientation *Stupor & coma
33
Glucocorticoids effects?
Control inflammation *Thyroid optic neuropathy (pressure on optic nerve) → Loss of eyesights
34
Thyroid storm intensive care?
1. Carbimazole every 4-6hrs 2. Iodine 8hrly 3. Glucocorticosteridos hourly 4. Propranolol hourly/Ca2+ - channel blockers
35
Hypothyroidism drugs?
1. Levothyroxine sodium(T4) 2. Liothyroxine(T3)
36
Levothyroxine sodium(T4)?
Synthetic thyroxine sodium
37
Levothyroxine sodium(T4) caution?
1. CVS disorders → Severe ischemic heart disease →Myocardial disease 2. Geriatics→ Dosage with ↓ with age 3. Paediatrics→ used with caution 4. Pregnancy → Limited crossing of placenta (No known A/E)
38
Levothyroxine sodium(T4) A/E?
1. Dose related Symptoms of hyperthyroidism
39
Levothyroxine sodium(T4) DI?
1. *Calcium carbonate *Ferrous sulphate All ↓ absorption of levothyroxine 2. Cholestyramine → Binds thyroxine in GIT, prevents absorption 3. Warfarin → ↑ Warfarin effects 4. Oestrogen→↑serum thryoid binding globin and alter thryoxine requirements 5. Sympathomimetics→Mutual increase in effects/CVS 6. Oral antidiabetic agents and insulin→ Requirements may change if thryoxine initiated for withdrawn
40
Levothyroxine sodium(T4) indications?
Pregnancy & congenital hypothyroidism -drug of choice
41
Hypothyroidism pharmacology drugs?
1. Levothyroxine sodium T3 2. Liothryoxine(T3)
42
Liothryoxine(T3) 1. Response 2. Strength 3. Cautions
1. Response very rapid thus given in acute situations only 2. Strength 5x stronger than levothryoxine 3. Cautions in geriatics & paediatrics -tailor dose to individual requiremenys
43
Liothryoxine(T3) I?
1. Cases where rapid response is required (Emergencies) 2. Hypothyroid coma 3. Sever hypothyroid state 4. 5'-deiodinase deficient patients
44
Thyroid cancer
-Surgical Removal of carcinogenic nodules -Benign nodules are harmless
45
Goitrous thyroid disease
-Lack of dietary iodine-thyroid gland enlarges in an attempt to produce more hormone -Iodine supplementtaion -If goite is too large: -Breathing/swallowing difficulty -If no response to treatment-surgery

Pharmacology (44 decks)

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