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Drug Action II > Block 4: Thyroid Pharm > Flashcards

Block 4: Thyroid Pharm Flashcards

1
Q

What is the tx for SIADH?

A

Mild to no sx: fluid restriction
Severe: Hypertonic saline must have greater Osm that urine or will make hyponatremia worse
* Increaseing Na too fast can cause Central pontine myelinolysis

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2
Q

What are the pharms that can be used for SIADH>

A
  1. Remove or correct offending cause
  2. Loop Diuretics
  3. Demeclocycline (antibiotic (tetracycline derivative) that also antagonizes ADH receptors)
    * ADR: Nephrogenic Diabetes Insipidus
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3
Q

Conivaptan

Class, Brand, MOA, Form

A

Vaprisol: Non selective vasopressin receptor antagonist
MOA: Blocks ADH-induced increase in cAMP in renal collecting ducts and prevents translocation of aquaporin 2
Form: IV formulation

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4
Q

Tolvaptan

Brand, Class, MOA, Form, ADR

A

Samsca: V2 selective Vasopressin Receptor Antagonist
MOA: blocks binding of ADH to the V2 receptor in kindeys
Forms: PO
* Less effect on vasculature (less hypotension) due to lack of V1a receptor antagonism
* Increases serum Na+

ADR: Dry mouth, thirst, constipation, hyperglycemia, urninary frequency

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5
Q

What are vasopressin preps?

A
  1. Synthetic arginine vasopressin (Vasostrict, human form)
  2. Desmopressin (1-deamino-8-D-arginine vasopressin, DAVP):
    * V2 effects > V1
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6
Q

What are the clinical uses for vasopressin?

A

Diagnostic to differentiate central vs neprhogenic DI:
* One hour after treatment, urine osmolality should increase >50 % if due to AVP deficiency (or central DI)

Replacement therapy for central DI: use desmopressin due to longer DOA

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7
Q

What are GI applications of vasopressin?

A
  1. Based on V1-mediated contraction of GI smooth muscle, can be used for postoperative ileus and to dispel intestinal gas before abdominal imaging
  2. Based on V1-mediated contraction of vascular smooth muscle can be used for emergency treatment of bleeding

Not DAVP

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8
Q

What are the ADR of V1?

A
  1. Constriction of blood and coronary vessels
  2. Stimulation of GI muscle
  3. Cross-reaction with the oxytocin receptor causing stimulation of uterine smooth muscle
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9
Q

What are the ADR of V2?

A

Rare

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10
Q

Tx for lithium induced nephrogenic DI?

A

Thiazide diuretics

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11
Q

Drug of choice for induction of labor? Monitoring?

A

Oxytocin: Monitor uterine activity, fetal heart rate

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12
Q

ADR of oxytocin?

A
  1. Uterine rupture
  2. Trauma or death of infant
  3. Risks minimized by use of conservative protocol
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13
Q

Apart from induction of labor what are other uses for oxytocin?

A
  1. Control of postpartum bleeding by maintain uterine tone
  2. Increasing milk ejection
  3. Oxytocin challenge test to measure uteroplacental sufficiency in high risk pregnancies
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14
Q

What is the tx for Growth Hormone Dependent (GHD) short stature?

A

Recombinant GH

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15
Q

When can Recombinant GH be initiated?

A

Early age, prior to the onset of puberty is associated with a more favorable increase in height

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16
Q

Outcomes of hyposecretion of GH?

A

Short stature:
1. Hypopituitary short stature (pituitary dwarfism)
2. Laron syndrome: Failure of GH to stimulate IGF-I production

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17
Q

What are the clinical tx for hyposecretion of GH?

A

Somatropin (Humatrope, Norditropin, & others):
* Recombinant human GH (rhGH) for SC & IM

Sustained-release rhGH formulations:
* Nutropin depot
* Skytrofa
* Sogroya
* Ngenla

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18
Q

What are the ADRs and DDIs of somatropin and somatrem?

A

ADR: peripheral edema, myalgias, arthralgias, carpal tunnel syndrome
DDI: Increased cytochrome P450 isoforms -> increased clearance of steroids, anticonvulvants, cyclosporine

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19
Q

What is increlex?

A

Mecasermin:
Long-term treatment of growth failure in children caused by severe primary IGF-1 deficiency (e.g. Laron syndrome)

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20
Q

What is the treatment choice for acromegaly?

A

Trans-sphenoidal surgical resection of the GH-secreting adenoma

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21
Q
A
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22
Q

What are the pharm tx for acromegaly?

A
  1. Somatostatin analogs (Somatostatin Receptor Ligands)
  2. Dopamine agonists
  3. GH receptor antagonist: Pegvisomant
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23
Q

What are the somatostatin analogs?

A
  1. Octreotide (Sandostatin)
  2. Lanreotide depot (Somatuline Depot)
  3. Pasireotide (Signifor)
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24
Q

Octreotide

Brand, Indications, MOA, Forms, ADR

A

Sandostatin
Indications: acromegaly
MOA: More potent at inhibiting GH secretion than native SRIF
FormsSustained-release form: Sandostatin LAR
ADR: HA, cardiac conduction changes, GI reactions

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25
Q

Lanreotide

Brand, Form, Indication, ADR

A

Somatuline Depot: Deep SQ Q28D
Indication: acromegaly
ADR: Reduction of bile production, gallbladder contractility leading to biliary sludge and/or gallstones, GI disturbances

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26
Q

Pasireotide

Brand, Forms, Indication, MOA, ADR

A

Signifor
Form: IM Preparation (Signifor LAR)
Indication: Cushings and acromegaly
MOA: Somatostatin analogue that acts via somatostatin receptors to inhibit the secretion of GH
ADR: Hyperglycemia

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27
Q

What is the GH analog?

A

Pegvisomant (Somavert)

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28
Q

Describe the structure of Pegvisomant?

A
  1. Recombinant hGH analog that act as a GHR antagonist
  2. Polyethylene Glycol derivative of a mutated Growth Hormone
  3. The mutated GH, B2036, prevents functional receptor dimerization with reduced binding affinity
  4. While pegylation reduces affinity for the GH receptor, requiring a higher dose requirement, pegylation increases half life by up to 6 days
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29
Q

What is the most effective tx for acromegaly?

A

Pegvisomant (Somavert)

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30
Q

What is the tx for prolactin hypersecretion?

A

Dopamine Agonists: Inhibits release of prolactin (inhibiting hormone)

31
Q

What are the types of dopamin agonists?

Forms, ADRs

A

Bromocriptine, Cabergoline, Ropinirole, Pramipexole
Form: PO
ADR: NV/DZ, postural hypotension

32
Q

What is the tx for cushings?

A

Steroidogenic inhibition

33
Q

What are the Steroidogenic inhibititors?

A
  1. Metyrapone
  2. Ketoconazole
  3. Levoketoconazole (Recorlev)
  4. Mitotane (Lysodren)
  5. Osilodrostat (Isturisa)
34
Q

MOA of metyrapone?

A

Inhibits cortisol synthesis by inhibiting 11-beta hydroxylase

35
Q

MOA of ketoconazole?

A
  1. Treatment of fungal infection
  2. inhibitor of mitochondrial P450 enzymes systems and 11-hydroxylase
36
Q

Levoketoconazole (Recorlev)

Clinical use

A

Cortisol synthesis inhibitor for patients whom surgery is not an option or curative

37
Q

Mitotane

Brand, MOA, ADR

A

Lysodren
MOA: Inhibits 11-hydroxylation of 11-desoxycortisol and 11-desoxycorticosterone and pregnenolone synthesis from cholesterol in adrenal cortex
* Reduces synthesis of cortisol and corticosterone

ADR: adrenal crisis in settings of shock or severe trauma, CNS toxicity

38
Q

Osilodrostat

Brand, Indication, MOA

A

Isturisa
Indication: nonsurgical tx of Cushing adults who don’t qualify for surgery
MOA: Potent cortisol synthesis inhibitor that blocks 11 beta-hydroxylase to interrupt the last step of the cortisol synthesis pathway

39
Q

What is adrenal or addidsonian crisis?

A
  1. Acute adrenocortical insufficiency which represents an endocrine emergency
  2. Most common cause of adrenal crisis is HPA-axis suppression brought on by chronic use of exogenous glucocorticoids and abrupt withdrawal
40
Q

What are the tx options for addisons?

A

Hydrocortisone, Cortisone, Prednisone
* Mimics normal diurnal adrenal rhythm

41
Q

Describe the selectivity of hydrocortisone?

A

Both glucocorticoid and mineralocorticoid activity

42
Q

What is the tx for hypoaldosteronism? MOA

A

Fludrocortisone: Acts as a potent mineralocoricoid with weak GCC activity

43
Q

Tx options for hyperaldosteronism?

A

Spironolactone (Aldactone)

44
Q

Spironolactone

Brand, MOA, Indication, ADR

A

Aldactone
MOA: competitive antagonist of aldosterone and blocks androgen receptors
Indications: aldosterone-producing adrenal adenomas, Idiopathic hyperaldosteronism, CHF, hypokalemia, CKD
ADR: due to adrogen receptor blocking
* Men: gynecomastia, feminization, sexual dysfunction
* Women: menstrual irregularities, breast tenderness and enlargement

45
Q

What are the prinicples of GCC?

A
  1. Response is a function of the specific receptors that are activated
  2. MOA of steroids is complex and not fully understood
  3. PK of GCC varies by agent
  4. Suppression of HPA-axis is a major concern when systemic steroids are withdrawn due to long-term suppression of the HPA axis
46
Q

T/F: Iodine is an ideal thyroid hormone replacement.

A

F: No benefit to giving iodine due to Wolff-Chaikoff effect

47
Q

What are the products for TH replacement?

A
  1. Synthetic Levothyroxine, T4 (Levo-T, Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid)
  2. Liothyronine, T3 (Cytomel, Triostat)
  3. Combined LT4 / LT3 (Liotrix)
48
Q

Levothyroxine

Brand, Dosing, Warning

A

(Synthroid, Levothroid, Levoxyl, Levo-T, Tirosint, Unithroid, others)
Dosing: T4 is converted in the body, start with reduced dose in elderly and patients with heart dx
DDI
* Inhibition of GI absorption of TH: Ca++, Al++, and Mg++, BASm Iron sulfate, sucralfate
* Increased metabolism of TH: Rifampin, Carbamazepine, Phenytoin, Phenobarbital, Sertraline

Warning: Narrow TI requiring titration

49
Q

Liothyronine

Brand, MOA

A

Cytomel, Triostat
MOA: 10x more potent -> palpitations or cardiac ADRs
* Causes high plasma T3 levels, lower T4 levels (this is not physiologic)

50
Q

Desiccated Thyroid

Brands, Forms

A

Nature-Throid, Westhroid, Armour
Form: Desiccated powder derived from porcine-thyroid
* Contains both T4 and T3 not necessarily consistent

51
Q

Tx options for hyperthyroidism?

A
  1. Palliative treatment of mild hyperthyroidism may be accomplished by using B-blockers
  2. Thyroidectomy
  3. Radioactive Iodine (131I)
52
Q

Radioactive Iodine

Safety, ADR

A

Safety:
* Eliminated in the urine, saliva and feces in the following 4-8 weeks
* No close contact with children and pregnant women for the first 48-72 hours after treatment

ADR: Graves ophthalmology can or may worsen (radioactive iodine does nothing for TSI levels)
CI: Pregnancy, lactation, active Graves’ ophthalmopathy

53
Q

How do you prevent the development of Graves opthalmology?

A

Prednisone

54
Q

What is the preferred tx method for hyperthyroidism by most thyroidologists?

A

Radioactive Iodine

55
Q

Tx for thyroid eye disease?

A

Tepezza (teprotumumab-trbw) is an insulin-like growth factor-1 receptor inhibitor

56
Q

What are thionamides indicated for?

A
  1. Hyperthyroidism in permanent remission in 40-50% of treated patients
  2. treatment of choice in children, pregnant women and young adults with uncomplicated Graves’ disease
57
Q

Types of thionamide?

A
  1. Propylthiouracil (PTU)
  2. Methimazole (Tapazole)
58
Q

Thionamides

MOA, Onset

A

MOA: Inhibitors of thyroid peroxidase enzyme (TPO) that is responsible for iodination of tyrosine residues of thyroglobulin
* Prevents TH syntheis

Onset: 4-6 week, TSK levels may remain undetectable for months
ADR: Dose dependent with Tapazole, idiosyncratic with PTU
* Agranulocytosis: common in PTU
* Hepatoxicity w/ PTU
* Cholestatic jaundice w/ Tapazole (resolves in 2-8 weeks with dc)

59
Q

Propylthiouracil (PTU)

MOA, Indication, ADR

A

MOA:thionamide action and inhibits the peripheral conversion of T4 to T3 (but not by methimazole)
Indication: Thyroid storm
ADR: Agranulocytosis, hepatotox, hepatic necrosis

60
Q

Methimazole

Brand, MOA, ADR

A

Tapazole
MOA: Inhibits thyroid peroxidase enzyme, decreasing iodination of tyrosines on thyroglobulin

ADR:
* Lower risk of agranulocytosis and hepatotoxicity
* Does NOT inhibit peripheral conversion of T4 to T3

61
Q

Outocmes of using Iodine for hyperthyroidism?

A
  1. Short term inhibitor of thyroid hormone release due to Wolff-Chaikoff effect
  2. The effect of iodide is overcome by TSH levels that increase in response to lower plasma levels of free thyroid hormone
  3. Not widely used: Occasionally used as preoperative preparation and thyroid storm
62
Q

Functions of beta blockers with hyperthyroidism?

A
  1. Decreases adrenergic activity of TH
  2. Blocks peripheral conversion of T4 to T3

Propranolol (nonselective) is preferred

Also use in thyroid storm and reduction of T4 conversion

63
Q

Functions of GCC with hyperthyroidism?

A
  1. Reduces effects of TSI in Graves’ Ophthalmopathy
  2. Blocks peripheral conversion of T4 to T3
64
Q

Wht is the initial tx for thyroid storm?

A

Initial stabilization includes airway protection, oxygenation, fluids and cardiac monitoring

65
Q

How is thyroid storm tx divides?

A
  1. General supportive care
  2. Inhibition of thyroid hormone synthesis
  3. Retardation of thyroid hormone release
  4. Blockade of peripheral thyroid hormone effects
  5. Identification and treatment of precipitating events
66
Q

What are the pharm tx for thyroid storm?

A
  1. Propylthiouracil or Methimazole: prevents synthesis of the TH hormone
  2. Treat cardiac symptoms, fever and hypertension: Propranolol decreases adrenergic hyperactivity and has the additional effect of blocking peripheral conversion of T4 -> T3
  3. Glucocorticoids: inhibit thyroid hormone production and decreases peripheral conversion from T4 -> T3.
  4. Sodium iodide solution (Lugol’s solution) or lithium: Do not administer iodine or lithium until the synthetic pathway has been blocked (with PTU or Methimazole)
67
Q

Drug disease interactions with TH?

A
  1. Diabetes and Hypoglycemic agents
  2. Estrogens may increase TBG -> decrease FT4
  3. Seizure disorder: TH can decrease seizure threshold
  4. Levothyroxine increases the response to oral anticoagulant therapy
  5. The therapeutic effects of digitalis glycosides may be reduced by levothyroxine
68
Q

DDI of TH?

A
  1. Drugs which may decrease thyroid hormone synthesis or secretion
  2. Drugs that may decrease T4 absorption from GI tract
  3. Drugs that may alter T4 and T3 serum transport
  4. Phenytoin and carbamazepine when used with levothyroxine can decrease the effects of levothyroxine
69
Q

What thyroid functions are altered with pregnacy?

A
  1. Transient increase in hCG, during the 1st trimester stimulates the TSH-R
  2. ) Estradiol increases thyroxine binding globulin (TBG) during the 1st trimester, which is sustained throughout pregnancy: ↓ FT4
  3. Iodine def
  4. Alterations in immune function
70
Q

How do you prevent hypothyroidism in pregnancy?

A

Women need more LT4 during pregnancy
* Dose changes based on serum FT4 +TSH

71
Q

RF of Graves in pregnancy?

A
  1. Fetal anomalies
  2. spontaneous abortion
  3. preterm labor
  4. fetal hyperthyroidism
  5. thyroid storm in labor
72
Q

Tx of Graves during pregnancy?

A
  1. Antithyroid drugs are still the primary treatment
  2. Propylthiouracil preferred 1st trimester
  3. Methimazole in 2nd and 3rd trimesters

ABSOLUTE CONTRAINDICATION…
No RAI while pregnant… Ever…

73
Q

Causes of postpartum thyroiditis?

A

Lymphocytic infiltration (Hashimoto’s)

Drug Action II (28 decks)

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