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Endo > SM_181b: Pituitary/Adrenal/Thyroid Pharmacology > Flashcards

SM_181b: Pituitary/Adrenal/Thyroid Pharmacology Flashcards

1
Q

Describe basic progression of hypothalamic signaling

A

Basic progression of hypothalamic signaling

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2
Q

Vasopressin (ADH) is a ____ hormone made in the ____

A

Vasopressin (ADH) is a peptide hormone made in the posterior pituitary

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3
Q

Vasopressin is secreted in response to ____ or ____ and functions to ____ and ____

A

Vasopressin is secreted in response to decreased blood pressure and hypertonicity and functions to raise blood pressure and promote water reabsorption

(fluid homeostasis)

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4
Q

Desmopressin is a ____ of vasopressin

A

Desmopressin is a synthetic long-acting analog of vasopressin

(1-desamino-8-D-arginine vasopressin)

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5
Q

Vasopressin and analogs act through ____

A

Vasopressin and analogs act through GPCRs

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6
Q

Vasopressin action on V1 receptor involves ____

A

Vasopressin action on V1 receptor involves coupling to Gq and PLC

  • PLC converts PIP2 to DAG and IP3
  • Vascular effects: IP3 -> Ca release -> vasoconstriction
  • CNS effects: bonding, depression
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7
Q

Vasopressin action on V2 receptor involve ____

A

Vasopressin action on V2 receptor involve coupling to Gs / adenylate cyclase to increase cAMP and PKA

  • Increases water reabsorption from collecting duct through insertion and stabilization of aquaporin-containing vesicles
  • Increases factor VIII and VWF
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8
Q

Desmopressin has much ____ antidiuretic / pressor activity than vasopressin and acts preferentially on ____ receptor

A

Desmopressin has much more antidiuretic / pressor activity than vasopressin and acts preferentially on V2 receptor

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9
Q
A
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10
Q

Vasopressin is used in treatment of ___

A

Vasopressin is used in treatment of central diabetes insipidus

  • Caused by inadequate secretion of endogenous vasopressin

(also used to stop bleeding from esophageal varices, desmopressin used to stop bleeding in Hemophilia A and von Willebrand’s disease)

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11
Q

Nephrogenic diabetes insipidus is ____

A

Nephrogenic diabetes insipidus is impaired renal response to vasopressin

  • Congenital or drug-induced (lithium)
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12
Q

Nephrogenic diabetes insipidus is treated with ___

A

Nephrogenic diabetes insipidus is treated with thiazide diuretics

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13
Q

SIADH is treated with ____ such as ____ and ____

A

SIADH is treated with vasopressin receptor antagonists such as conivaptan and tolvaptan

  • Tolvaptan is more selective for V2 receptors and is orally effective but can be hepatotoxic
  • Etiology of SIADH: malignancy, head injuries, drugs (psychotropics, sulfonylureas, vinca alkaloids)
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14
Q

Oxytocin is similar in structure to ____

A

Oxytocin is similar in structure to oxytocin

(9 amino acid peptides)

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15
Q

Oxytocin activates ____

A

Oxytocin activates GPCRs on smooth muscle for contraction

  • Gq -> PLC -> Ca -> calmodulin -> myosin
  • Promotes release of prostaglandins and leukotrienes
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16
Q

Oxytocin is used to ____ and ____

A

Oxytocin is used to induce labor under restricted conditions and control postpartum uterine hemorrhage

  • Induce labor under restricted conditions: when early vaginal delivery is complicated (eclampsia), when labor is protracted or arrested
  • Hepatic and renal metabolism
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17
Q

Growth hormone is a ____ produced in the ____

A

Growth hormone is a 191-amino acid peptide produces in somatotropes of the anterior pituitary

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18
Q

Growth hormone is positively regulated by ____ and negatively regulated by ____ and ____

A

Growth hormone is positively regulated by GHRH and negatively regulated by somatostatin and dopamine

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19
Q

Describe the action of growth hormone

A

Growth hormone action

  • Stimulates longitudinal growth of bone until epiphyseal closure
  • Increases muscle mass
  • Decreases central adiposity
  • Reduces sensitivity to insluin
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20
Q

GH deficiency during childhood / adolescence results in ____, ____, and ____

A

GH deficiency during childhood / adolescence results in short stature, decreases muscle mass, and increased body fat

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21
Q

GH acts through homodimeric ____ membrane receptors

A

GH acts through homodimeric tyrosine-kinase linked membrane receptors (JAK)

  • JAK causes activation of STAT proteins and subsequent downstream effects
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22
Q

Most of the actions of GH are mediated through hepatic production of ____

A

Most of the actions of GH are mediated through hepatic production of insulin-like growth factor-I (IGF-I)

  • IGF-I synthesis can also be stimulated by other agents
  • IGF-I and GH can downregulate GH secretion
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23
Q

____ and ____ are GH agonists

A

Somatropin and somatrem are GH agonists

  • Somatropin: recombinant peptide that is identical to native human GH
  • Somatrem: has additional methionine, prolonging half life
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24
Q

Describe uses of GH

A

GH uses

  • Replacement in children with GH
  • Other causes of short stature (Turner, Prader-Willi, chronic renal insufficiency, idiopathic short stature)
  • Used for AIDS wasting, malabsorption
  • Abused as anti-aging remedy
  • Illegally used in sports
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25
Q

____ and ____ are IGF-1 agonists

A

Mecasermin and mecasermin rinfabate are IGF-1 agonists

  • Mecasermin: recombinant form of IGF-1
  • Mecasermin rinfabate: contains IGF-1 and IGF-1 binding protein IGFBP-3, which prolongs half life
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26
Q

IGF-1 agonists are used to ____

A

IGF-1 agonists are used to promote growth and normalize metabolism in IGF-1 deficiency resistant to GH

(mecasermin, mecasermin rinfabate)

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27
Q

Acromegally results in ____ leading to ____

A

Acromegally results in GH excess leading to abnormal growth of bone and cartilage

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28
Q

____, ____, and ____ are drug treatments for GH excess

A

Somatostatin analog octreotide, GH receptor antagonist pegvisomant, and dopaminergic agonists are drug treatments for GH excess

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29
Q

Octreotide is ____ than somatostatin in inhibiting GH secretion

A

Octreotide is more potent than somatostatin in inhibiting GH secretion

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30
Q

Otreotide acts through ____ receptors to activate ____ and ____

A

Otreotide acts through somatostatin receptors receptors to activate K channels and protein phosphotyrosine phosphotases

  • Somatostatin receptors: family of GPCRs that couple through Gi
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31
Q

Octreotide acts to ____

A

Octreotide acts to inhibit GH secretion

  • Also inhibits secretion of TSH, ACTH, glucagon, gastrin, insulin
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32
Q

Octreotide is used for ____, ____, ____, and ____

A

Octreotide is used for acromegaly, other hormone-secreting tumors, secretory diarrhea from chemotherapy, and dumping syndrome after gastric surgery

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33
Q

____ is a long acting analog of octreotide

A

Lanreotide is a long acting analog of octreotide

(somatostatin analog -> GH antagonist)

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34
Q

Pegvisomant is a ____ that is a ____

A

Pegvisomant is a modified mutant form of growth hormone that is a GH receptor antagonist

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35
Q

Pegvisomant functions to ____

A

Pegvisomant functions to allow receptor dimerization but blocks subsequent signaling, preventing activation of JAK-STAT and secretion of IGF-1

(GH receptor antagonist)

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36
Q

Pegvisomant is used to treat ____

A

Pegvisomant is used to treat acromegaly

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37
Q

____ and ____ are D2 agonists

A

Bromocriptine and cabergoline are D2 agonists

  • GH antagonists
  • Semisynthetic ergot alkaloids
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38
Q

Describe the mechanism of bromocriptine and cabergoline

A

Bromocriptine and cabergoline mechanism

  • Selective dopamine D2 receptor agonists
  • Mimic effects of dopamine to inhibit GH production and secretion
  • Even more effective in inhibiting prolactin
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39
Q

Bromocriptine and cabergoline are used to treat ____ and ____

A

Bromocriptine and cabergoline are used to treat acromegaly and hyperprolactinemia / galactorrhea resulting from injuries/tumors/drugs

40
Q

Cabergoline is ____ potent and has ____ half life than bromocriptine

A

Cabergoline is more potent and has longer half life than bromocriptine

41
Q

Somatostatin ____ growth hormone

A

Somatostatin inhibits growth hormone

42
Q

Thyroid hormones are ____

A

Thyroid hormones are iodinated dipeptides derived from tyrosine residues on the protein thyroglobulin in the thyroid gland

43
Q

T4 is ____

A

T4 is levothyroxine / thyroxin

44
Q

T3 is ____

A

T3 is triiodothyronine / liothyronine

45
Q

Thyroid hormones act through ____ to regulate ____

A

Thyroid hormones act through nuclear receptors to regulate genes

  • Receptor distribution varies: B1 > a1 in liver, a1 > B1 in heart, B2 in hypothalamus, a2 inactive and non-binding
46
Q

Thyroid hormones act on ____ receptors, which interact with response elements as ____

A

Thyroid hormones act on nuclear receptors, which interact with response elements as heterodimers (e.g. RXR/TR)

47
Q

Thyroid hormones are critical for development of the ____ and ____

A

Thyroid hormones are critical for development of the CNS and skeleton

48
Q

Perinatal thyroid hormone deficiency can result in ____, ____, and ____

A

Perinatal thyroid hormone deficiency can result in mental impairment, learning disabilities, and skeletal defects

49
Q

Describe non-development actions of thyroid hormones

A

Non-development actions of thyroid hormones

  • Metabolic: optimize energy metabolism and reproductive function
  • Cardiac: inotropic and chronotropic effects: potentiate effects of sympathomimetic amines
  • Hepatic: increase cholesterol metabolism, effects on glucose metabolism cause insulin resistance
  • Skeletal: possibly promote osteoporosis
50
Q

Describe target genes of thyroid hormones

A

Target genes of thyroid hormones

  • Myelin basic protein: brain development:
  • Ca2+ ATPase in skeletal muscle: calorigenic effects
  • Ion channel protein in pacemaker: chronotropic effect
  • B-adrenergic receptor: potentiate cardiac adrenergic effects
  • IGF-I: bone formation
51
Q

Describe the hypothalamus-pituitary-thyroid axis

A

Hypothalamus-pituitary-thyroid axis

  1. TRH (hypothalamus)
  2. TSH (pituitary)
  3. T3, T4 (thyroid)
  4. T3 and T4 negatively regulate TRH and TSH
52
Q

Thyroid hormones are used as ____

A

Thyroid hormones are used as suppressive therapy after thryoidectomy for malignancy

53
Q

Measuring TSH is a sensitive test for determining ____ and ____

A

Measuring TSH is a sensitive test for determining thyroid hormone status and effectiveness of anti-thyroid therapy

54
Q

Even though T3 has more favorable pharmacokinetic properties, T4 is the preparation of choice due to ____ and ____

A

Even though T3 has more favorable pharmacokinetic properties, T4 is the preparation of choice due to more convenient dosage (qd) and lower risk

55
Q

Thyroid hormone is used to treat ____

A

Thyroid hormone is used to treat hypothyroidism

  • Due to Hashimoto’s thyroiditis, synthetic enzyme defects, destruction of thyroid by medical treatments, and secondary hypothyroidism
56
Q

Describe effects of thyroid hormone replacement

A

Thyroid hormone replacement effects

  • Metabolic: improve energy metabolism and reproductive function
  • Cardiac: inotropic and chronotropic effects
  • Hepatic: increase cholesterol metabolism
57
Q

Thyroid hormone agents selective for ____ have been developed as cholesterol lowering drugs

A

Thyroid hormone agents selective for TR-beta have been developed as cholesterol lowering drugs (VK2809)

  • Hepatic effects on cholesterol metabolism mediated mainly by TR-beta receptors
  • Unwanted cardiac effects mediated through TR-alpha receptors
58
Q

Chronic excess of thyroid hormones can result in ____, ____, ____, ____, ____, and ____

A

Chronic excess of thyroid hormones can result muscle weakness, anemia, infertility, high output cardiac failure, bone loss, insulin resistance

59
Q

Some signs of hypothyroidism ____ necessitating caution in use of thryoid hormones

A

Some signs of hypothyroidism can have other causes necessitating caution in use of thryoid hormones

(lethargy, fatigue, weight gain, infertility)

60
Q

Hyperthyroidism involves ____

A

Hyperthyroidism involves hyperplasia in the thyroid

  • Diffuse toxic goiter
  • Toxic nodular goiter
  • Thyroid adenoma
61
Q

Describe symptoms of hyperthyroidism

A

Hyperthyroidism symptoms

  • Weight loss, excessive swelling, diarrhea, anxiety, headaches
  • Palpitations, angina, coronary and cerebral thromboses due to increased beta-adrenergic receptors or enhancement of signaling (cAMP)
62
Q

Chronic hyperthyroidism can result in ____, ____, ____, ____, ____, and ____

A

Chronic hyperthyroidism can result in muscle weakness, anemia, infertility, high output cardiac failure, bone loss, and insulin resistance

63
Q

Describe therapies for hyperthyroidism

A

Hyperthyroidism therapies

  • Surgery
  • Radioactive iodine (131I)
  • Thioureylene / thionamide anti-thyroid drugs
  • Sympatholytic agents
  • Potassium iodide
64
Q

Anti-thyroid therapy targets are ____, ____, ____, and ____

A

Anti-thyroid therapy targets are oxidation, coupling, proteolysis, and secretion

(prevent formation of T3 and T4)

65
Q

Describe action of 131I to treat hyperthyroidism

A

131I to treat hyperthyroidism

  • Gamma and beta emitter
  • Administered orally, absorption is rapid
  • 131I trapped, incorporated, deposited in colloid
  • Released beta particles cause necrosis of follicular cells
  • Symptoms of hyperthyroidism abate over weeks to months
  • Not used in pregnant or nursing women
66
Q

Methimazole acts by ____

A

Methimazole acts by inhibiting thyroid peroxidase to block iodination and coupling

67
Q

Propylthiouracil acts by ____ and ____

A

Propylthiouracil acts by inhibiting thyroid peroxidase to block iodination and coupling and inhibits peripheral conversion of T4 to T3

68
Q

Describe sympatholytic therapy for hyperthyroidism

A

Sympatholytic therapy for hyperthyroidism

  • Beta-adrenergic receptor blockers (propranolol, atenolol)
  • Control tachycardia, HTN, atrial fibrillation, during acute phase of thyrotoxicosis
  • Control BP chronically
  • Propranolol is a weak inhibitor of peripheral T4 to T3 conversion
69
Q

Potassium iodide treats hyperthryoidism by ____

A

Potassium iodide treats hyperthryoidism by inhibiting thyroglobulin proteolysis and hormone release

70
Q

Describe adrenal steroid pharmacology

A

Adrenal steroid pharmacology

  • Glucocorticoid and mineralocorticoid uses related to classical actions: to restore physiologic concentrations and conditions
  • Glucocorticoid uses related to anti-inflammatory, immunosuppressive, anticancer actions: require supraphysiologic concentrations
71
Q

Describe mechanism of action of adrenal steroids

A

Adrenal steroids mechanism of action

  1. Interact with receptors in cytoplasm
  2. Release of heat shock protein Hsp90
  3. Exposes DNA binding domain of receptor
  4. Allows translocation to the nucleus
  5. Receptors bind as homodimers
  6. Interact with response elements
  7. Regulate target gene transcription
72
Q

Glucocorticoid receptor can also interact with other transcription factors, which may play a role in _____ effects of glucocorticoids

A

Glucocorticoid receptor can also interact with other transcription factors, which may play a role in non-endocrine effects of glucocorticoids

73
Q

Describe metabolic actions of glucocortoids

A

Glucocorticoid metabolic actions

  • Liver: conservation of glucose (promote glycogen synthesis and stimulate gluconeogenesis)
  • Connective tissues: decrease protein synthesis, promote protein breakdown -> muscle wasting, skin thinning, osteoporosis
  • Adipose: fat redistribution, truncal obesity
74
Q
A
75
Q

Describe non-metabolic actions of glucocorticoids

A

Glucocorticoid non-metabolic actions

  • Kidney: increase Ca excretion, mineralocorticoid activity results in renal NA retention, K and H excretion
  • Immune system: decrease Ab production, antigen processing, decrease lymphocytes, cytokines, prostaglandins
  • GI: cause thinning of mucus, increase acid and pepsin secretion, decrease Ca absorption
  • CNS: euphoria, depression, psychoses, sleep disturbances, decrease threshold for electrical excitation
  • Stress response: increase cardiac output, glomerular filtration rate
76
Q

Addison’s disease presents with ____ and ____ and requires replacement of ____ and ____

A

Addison’s disease presents with muscle weakness and low blood pressure and requires replacement of glucocorticoids and mineralocorticoids

77
Q

Acute loss of adrenal function requires ____

A

Acute loss of adrenal function requires glucocorticoids and salt and water

78
Q

ACTH deficiency requires ____

A

ACTH deficiency requires glucocorticoid replacement

79
Q

Congenital adrenal hyperplasia is when ____, leading to ____ and ____

A

Congenital adrenal hyperplasia is when a hydroxylase essential for adrenal steroid synthesis is deficient, leading to decreased hydrocortisone / cortisol and insufficient/excess mineralocorticoids and / or androgens

  • Treated with adrenal steroids
80
Q

Pituitary exerts ____ on adrenal

A

Pituitary exerts negative feedback on adrenal

81
Q

21-hydroxylase deficiency involves ____, ____, and ____

A

21-hydroxylase deficiency involves low glucocorticoids and mineralocorticoids, high ACTH, increased secretion of androgens

82
Q

21-hydroxylase deficiency is treated with ____ and ____

A

21-hydroxylase deficiency is treated with glucocorticoid and mineralocorticoid replacement

83
Q

11-hydroxylase deficiency involves ____, ____, and ____

A

11-hydroxylase deficiency involves low glucocorticoids, high ACTH, and increased secretion of mineralocorticoids and androgens

84
Q

Adrenal hyperfunction can be ____ or ____

A

Adrenal hyperfunction can be primary or secondary to increased ACTH

  • Primary: adrenal adenoma, carcinoma
  • Secondary to increased ACT: pituitary adenoma, ectopic ACTH
85
Q

Describe drug treatment for adrenal hyperfunction

A

Adrenal hyperfunction drug treatment

  • Mifepristone / RU-486: glucocorticoid receptor antagonist
  • Metyrapone: blocks 11-hydroxylase
  • Ketoconazole: blocks multiple steps in pathway
  • Aminoglutethimide: blocks cholesterol side chain cleavage
  • Mitotane: most toxic, used for carcinoma
  • Somatostatin analogs: suppress elevated ACTH
86
Q

ACTH test is used to ____

A

ACTH test is used to determine etiology of pituitary-adrenal axis hypfunction (low glucocorticoids)

87
Q

Exogenous ACTH will stimulate adrenal secretion if insufficiency is due to ____ but not ____

A

Exogenous ACTH will stimulate adrenal secretion if insufficiency is due to inadequate ACTH secretion but not adrenal failure

88
Q

Metyrapone test is used to ____

A

Metyrapone test is used to determine etiology of pituitary-adrenal axis hypofunction (low glucocorticoids)

89
Q

Blocking 11-hydroxylase with metyrapone will ____, leading to ____ and ____

A

Blocking 11-hydroxylase with metyrapone will decrease glucocorticoid production, leading to decreased negative feedback and increased ACTH secretion

  • Used to determine extent to which pituitary is stimulated
90
Q

Dexamethasone is used to ____

A

Dexamethasone is used to determine etiology of pituitary-adrenal axis hyperfunction (high glucocorticoids)

  • Dexamethasone is potent glucocorticoid that will not interfere with assays for endogenous glucocorticoids
  • Used to test whether response is repressible
  • Will usually suppress ACTH from pituitary adenomas but not ectopic ACTH
91
Q
A
92
Q

Describe clinical uses of glucocorticoids

A

Glucocorticoid clinical uses

  • Anti-inflammatory and immunosuppressive actions: decreases cytokine and prostaglandin synthesis, WBCs, antibody production and antigen processing, scar formation
  • Anti-cancer actions (as chemotherapeutic agents): decrease lymphocytes, promote differentiation
93
Q

Describe desirable and undesirable effects of glucocorticoids at pharmacological doses

A

Desirable and undesirable effects of glucocorticoids at pharmacological doses

  • Desirable: anti-inflammatory, immunosuppressant, promote differentiation
  • Undesirable: more glucocorticoid-mediated mineralocorticoid activity, sodium retention, hypertension
94
Q

Glucocorticoids are most often bound to ___ and most frequently inactivated in the ___

A

Glucocorticoids are most often bound to CBG and most frequently inactivated in the liver

95
Q

Describe adverse effects of glucocorticoids

A

Glucocorticoid adverse effects

  • Hypokalemic alkalosis
  • Glycosuria
  • Susceptibility / masking infection
  • Ulcers
  • Myopathy
  • Osteoporosis
  • Hypercoagulability
  • Psychoses
  • Glaucoma
  • Reproductive disturbance
  • Adrenal insufficiency after steroid withdrawal
96
Q

Preventing ___ in steroid withdrawal may be helpful

A

Preventing adrenal insufficiency in steroid withdrawal may be helpful

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