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Pharmacology > Anti-thyroid drugs > Flashcards

Anti-thyroid drugs Flashcards

1
Q

What is the recommended sodium intake per day?

A

150mcg

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2
Q

What transports Iodide to colloid which will be oxidized to Iodine via thryopoietin?

A

Pendrin

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3
Q

What are the 2 phenomenon that induces hyper- & Hypothyroidism?

A

Wolff-Chaikoff effect -> Hypothyroidism
Jod-Basedown Phenomenon -> Hyperthyroidism

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4
Q

What occurs in Wolff-Chaikoff effects & Jod-Basedown phenomenon?

A

Jod-Basedow phenomenon –> Impaired auroregulation –> escape from neg feedback –> Hyperthyroidism

Wolff-CHaikoff effect –> protective autoregulatory inhibition of organification –> protects TG –> hypothyroidism

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5
Q

What is the difference betw the duration of Wolff-Chaikoff effects & Jod-Basedown phenomenon?

A

WC effect –> transient physiologic response (24-48hrs)
HB phenomenon –> pathologic response that can lead to a thyroid storm

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6
Q

In what conditions do Wolff-Chaikoff effect & Jod-Basedown phenomenon occur?

A

Hashmito’s thyroiditis -> WC effect
Graves’ Disease –> JB Phenomenon

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7
Q

What are the 2 types of hypothyroidism & what is its difference?

A

Primary –> problem within the TG –> Iodine deficiency
Central hypothyroidism –> problem in either PG or Hypothalamus –> TSH deficit

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8
Q

What is the problem in secondary & tertiary central hypothyroidism?

A

2ndary => pituitary disease –> TSH deficit
3ary => Hypothalamic disease –> TRH deficit

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9
Q

What are the diff conditions that causes primary hypothyroidism?

A

Congenital hypothyroidism => Dyshormonogenesis, Dysgenesis
Hashimoto’s thyroiditis => Autoimmune destruction of thyroid via anti-TPO
Iatrogenic hypothyroidism => After iodinated contrast media

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10
Q

Which of the 2 thyroid hormones (T3 & T4) are absorbed better orally?

A

T3 = 95%

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11
Q

Which of the thyroid hormones is more protein-bound?

A

T4 = 99.96%

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12
Q

Which of the thyroid hormones is more potent biologically?

A

T3

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13
Q

Which of the thyroid hormones has a greater total & free serum concentration?

A

T3

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14
Q

What can impair T4 absorption?

A

interactions with food like brain, fiber, soy, coffee

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15
Q

What is the thyroid function test result in Hypothyroidism?

A

HIGH = TSH
LOW = Total T4, Total T3, Free Te & T4

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16
Q

What is the result of thyroid function test result in HYPERthyroidism?

A

HIGH = Total T3 & T4, Free T3 & T4
LOW = TSH

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17
Q

Why is it that T3 is more biologically active than T4?

A

because TH receptor has a greater affinity to T3 than T4

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18
Q

What are the diff effects of Thyroid hormones?

A

Growth & Development (brain & repro tissues)
Metab of CHO, Fats, CHON, vitamins, & drugs
Secretion & Degradation rates of all other hormones
INC Beta-adrenergic receptors and amplification of its signal (Palpitations, tachycardia, tremor, sweating, anxiety, heat intolerance)

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19
Q

What are the clinical uses of T3 & T4?

A

Levothyroxine replacement therapy in HYPOthyroidism –> regression on nontoxic goiter if present

–> TSH suppression –> post thyroidectomy in thyroid cancer –> DEC risk of tumor recurrence

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20
Q

What are the 2 preparations of T3, T4?

A

Synthetic T3 (Liothyronine)
Synthetic T4 (Levothyroxine)

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21
Q

Which of the 2 preparations of Thyroid hormones is used for SHORT term TSH suppression to DEC risk of cardiotoxicity due to elevations in peak levels?

A

Synthetic T3 (Liothyronine) –> T3 + T4 combination

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22
Q

Why is Synthetic T4 (Levothyroxine) the preparation of choice between the 2?

A

stability & content uniformity
lack of allergenic foreign protein
long halflife (7 days)
easy lab monitoring & low cost

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23
Q

What is the basis for T4 monotherapy?

A

peripheral T4 to T3 conversion

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24
Q

How much Levothyroxine is given in px?

A

50-100mcg/day
-> INC dose in pedia, preggos & thryoid cancer px
-> DEC dose in elderly & cardiac px

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25
Q

What are the special instructions for administration & monitoring of Levothyroxine?

A

Take on an empty stomach 1hr before or 4 hrs after meal
Measure serum TSH & FT4 before any change in dosage

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26
Q

What are the possbile implications of T4 toxicity when administering Levothyroxine?

A

Pedia: restlnessness, accelerate bone growth
Adult: symptoms of hyperthyroidism
Elderly: A-fib & Osteoporosis

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27
Q

At what point after administering Levothyroxine do you administer activated charcoal ?

A

Thyroxine toxicity

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28
Q

In what case do you decrease the dose of Levothyroxine?

A

Androgen, antibiotic steroids, asparaginase administration can DEC TBG

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29
Q

In what case do you INC the dose of Levothyroxine?

A

to INC metabolism of TH ,TBG (Enzyme inducers, Estrogen, Tamoxifen, Raloxifene, Methadone) & DEC peripheral conversion (Propanolol, Corticosteroids, Amiodarone)

30
Q

What are the important C/Is of Levothyroxine?

A

Uncorrected adrenal insufficiency –> adrenal crisis
BBW –> DO NOT use to tx obesity/promote weight loss

31
Q

What is the end state of untreated/decompensated HYPOthyroidism associated with progressive weakness, STUPOR, hypothermia, hypoventilation, hypoglycemia, hyponetremia, H2O intoxication, shock, & Death?

A

Myxedema coma

32
Q

What should be given in px in Myxedema coma?

A

IV Levothyroxine 300-400mcg loading dose
50-100mcg daily

33
Q

What are the diff causes of HYPERthyroidism?

A

Iodine excess
Amiodarone-induce thyrotoxicosis
Graves disease
Toxic nodular goiter (Plummer disease)
Subcute thyroiditis
Pregnancy
Pitutary adenoma

34
Q

What condition has a goiter caused by a single toxic nodule?

A

Plummer disease/Toxic (uni- or multi-) nodular goiter

35
Q

What condition develops Ab against TSH receptors where instead of attacking/destroying them, they stimulate it?

A

Graves’ disease
anti-TSH-Receptor

36
Q

What condition has Amiodarone causing the disease of peripheral conversion of T4 to T3 and results in hypothyroidism? What causes this condition hyperthyroidism?

A

Amiodarone-induced thyrotoxicosis

Presence of iodine in Amiodarone that can induce hyperthyroidism (~3% only)

37
Q

What is the diff betw HYPERthyroidism & Thyrotoxicosis?

A

Hyperthyroidism = INC synthesis & secretion of TH
Thyrotoxicosis = Excess circulating TH

38
Q

What are important clin manifestations of HYPERthyroidism?

A

Retracted upper lids, bulging eyes, moist skin, INC HR, INC BMR, Heat intolerance, INC hormone degradation, anxiety, INC drug metabolism, DEC weight loss

39
Q

What are the 6 anti-thyroid drugs?

A

Thioamides
Anions
Iodides
Radioactive Iodine
Beta blockers w/o ISA
Glucocorticoids

40
Q

What are the 2 thioamides?

A

Methimazole
Propylithiouracil

41
Q

Which of the 2 thioamides is more potent, higher transfer across placenta, longer DOA?

A

Methimazole (MMI)

Distribution = concentrated by Thyroid Gland

42
Q

What is the DOC betw the 2 thioamides? What is preferred during 1st trim of preggos?

A

Methimazole

Preggos: Poprylthiouracil

43
Q

What is the MOA of Thioamides & Clinical use?

A

MOA: inhibits iodine organification & coupling of MIT/DIT
-> PTU: inhibits peripheral deiodination of T3 &T4

Use:
-> HYPERthyroidism (primary tx)
-> adjunct to thyroid surgery for toxic multinodular goiter

44
Q

What are the diff Anions (anti-TD)?

A

Perchlorate, Pertechnetate, Thiocyanate

45
Q

What is the MOA, use, & Serious AE of Anions?

A

MOA: Blocks Iodide uptake through competitive inhibition of Na iodide transporter

Use: Amiodarone-induced hyperthyroidism type I

AE: Aplastic anemia (Disuse)

46
Q

What are the 2 Iodides (anti-TD)?

A

KI and Lugols’ soln

47
Q

What is the primary tx of HYPERthyroidism/

A

Methimazole

48
Q

What are the actions of Iodides on TG?

A

DEC size
Inhibits proteolysis, DEC hormone release
Symptomatic, rapid relief in thyroid storm
Adjuvant to thyroid surgery
SHORT-TERM clinical use

49
Q

What condition can form if there is persistent Wolff-Chaikoff?

A

Fetal goiter; that’s why it is avoided during preggos

50
Q

Should Iodides be administered w/ food or diluted fluids?

A

YES

51
Q

What is the MOA of radioactive iodine?

A

emission of beta rays –> destruction of Thyroid parenchyma

52
Q

What are the clinical uses of Radioactive iodine?

A

Permanent cure of thyrotoxicosis
Tx of inoperable thyroid cancer
Adjuvant therapy to surgery for thyroid cancer

53
Q

What are C/I of Radioactive iodine & important AEs?

A

C/I: Preggos & lactation
AE: permanent hypothyroidism

54
Q

What is the MOA of beta-blockers w/o ISA?

A

competitively blocks beta-adrenergic receptors, ameliorating clinical signs and sympotoms of thyrotoxicosis & thyroid storm

Atenolol, Metroprolol, Propranolol

55
Q

Which BB inhibits peripheral conversion of T4 to T3 & REDUCES T3?

A

Propranolol @ >160mg/day

56
Q

What are the uses of BB in thyroid diseases , AE, & C/I?

A

Use: Control tachycardia, HTN, A-Fib
AE: Bronchospasm, bradycardia, hypotension
C/I: Bronchial asthma, Severe HF

57
Q

What anti-inflam agent is used in severe hyperthyroidism?

A

Glucocorticoids

58
Q

What conditions uses Glucocorticoids during severe HYPERthyroidism?

A

to manage thyroiditis in Amiodarone or infection
Relieves Sx of Graves ophthalmopathy
Manages severe metabolic stress in neonatal Graves’ disease

59
Q

What conditions thyroid diseases use Oral Prednisone?

A

AIT type II
Severe subacute thyroiditis
Severe Graves’ disease

60
Q

What thyroid disease uses Topical Triamclinolone covered w/ occlusive dressing? !!!!!

A

Graves’ dermopathy

61
Q

What thyroid disease uses IV Hydrocorticosterone to protect the px against shock & reduce circulating TH levels by peripheral inhibition?

!!!

A

Thyroid storm

62
Q

What are diff special problems in special populations?

A

Graves’ ophthalmopathy
Thyroid storm
Neonatal Graves’ disease

63
Q

What drug is given in CVS symptoms of Thyrotoxicosis?

A

Propranolol

64
Q

What is the prevention of progression of Graves’ ophthalmopathy?

A

Smoking cessation

65
Q

What DOC is given to Graves’ opthalmopathy?

A

Oral Prednisone
Alt: irradiation of posterior orbit

66
Q

What are tx of underlying thyroid dis & management of complications?

A

Tx of underlying thyroid dis: Surgery or RAI
Management of complications:
-> threatened visual loss: SURGICAL DECOMPRESSION OF ORBUT
-> residual eyelid/eye muscle problems: SURGERY

67
Q

What drugs are used in cases of thyroid storm?

A

Propanolol
Propylthiouracil
Hydrocortisone

68
Q

What is the cause of neonatal graves’ dis?

A

Passage of maternal TSH-R Ab through placenta into fetus

69
Q

What are the drug measures for neonatal Graves’ dis?

A

PROPYLthiouracil
Propanolol
K Iodide (Lugol’s soln)
Prednisone

70
Q

What is given in 1st, 2nd, & 3rd trimester of preggo mothers w/ HYPERTHYROIDISM

A

1st trim = Polythiouracil
2nd & 3rd trim = Methimazole

71
Q

What is given in preggos mothers with HYPOTHYROIDISM?

A

Levothyroxine

72
Q

What is a definitive therapy given in subtotal thyroidectomy in 2nd trimester?

A

Methimazole

Pharmacology (19 decks)

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