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Endocrine System > Pharamcology of pituitary drugs > Flashcards

Pharamcology of pituitary drugs Flashcards

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1
Q

What is acromegaly?

A

A disorder caused by excess growth of hormones, increasing the growth of body tissues and causing metabolic dysfunction (occurs in adults)

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2
Q

What are the characteristics of Acromegaly?

A
  1. Swelling of soft tissues in hands and feet
  2. Enlarged bones in the skull, hands, and feet
  3. Joint pains
  4. Headaches
  5. Barrel chest
  6. Cardiomegaly
  7. Carpal tunnel syndrome
  8. Diabetes
  9. HTN
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3
Q

What is the target of pharmacotherapy (acromegaly)?

A

Decrease the production of GH, activity of GH and release of IGF-1

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4
Q

What is hyperprolactinemia?

A

PRL is elevated: galactorrhea in non-breastfeeding women or in men, pituitray microadenoma or adenoma

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5
Q

What is the target of pharmacotherapy in hyperprolactinemia?

A

Decrease PRL formation, dopamine like molecules

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6
Q

What are the different types of pituitary drugs?

A

Somatostatin analogues
GH receptor antagonists
Dopamine agonists

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7
Q

What is the function of somatostatin analogues?

A

Enhance somatostatin -mediated inhibition of GH release

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8
Q

What are examples of somatostatin analogues?

A

Octreotide
Lanreotide
Pasireotide

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9
Q

What is the function of GHR antagonists?

A

Antagonists, competitive inhibitors, at GH receptors

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10
Q

What are examples of GHR antagonists?

A

Pegvisomant

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11
Q

What is the function of dopamine agonists?

A

Enhance D2 dopamine receptor activity

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12
Q

What are examples of dopamine agonists?

A

Bromocriptine
Cabergoline
Quinagolide

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13
Q

What is somatostatin?

A

A small polypeptide is also found in neurons throughout the body, intestine, stomach, and pancreas (SST14 and SST28)

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14
Q

What is the function of somatostatin?

A

Inhibits the release of not only GH but also insulin , glucagon and gastrin

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15
Q

How many isoforms of somatostatin are there?

A

5, all coupled to G proteinsn

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16
Q

Which isoforms of somatostatin are expressed in the anterior pituitary?

A

SST1, 2, 3, 5 (all expressed from 4), but they are all expressed to different extents

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17
Q

What are the SST analogues?

A

They are synthetic analogues of SST

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18
Q

What is the half-life of SSt analogs like in comparison to SST?

A

Longer half-life than SST
SST –> 1 to 3 minutes

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19
Q

Which receptors do SST analogues bind to preferentialy?

A

SST2 and SST5 receptors

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20
Q

What is the MOA of SST analogues?

A
  1. Hormone Secretion Inhibition: Inhibition of adenylyl cyclase (AC)
  2. Anti-Proliferative and Growth-Inhibitory Effects: Pathways involved in cell proliferation inhibition:
    –> Protein Tyrosine Phosphatase (PTP)
    –> Akt pathway inhibition
  3. Induction of apoptosis
  4. Anti-angiogenesis
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21
Q

What is the hormone secretion inhibition action of SST analogues?

A
  1. Activation of SSTs reduces intracellular cyclic AMP (cAMP) levels, which leads to decreased calcium influx ([Ca²⁺]) into the cell.
  2. The reduction in calcium levels inhibits exocytosis of secretory vesicles, resulting in decreased hormone secretion.
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22
Q

What are the anti-proliferative and growth-inhibitory effects of the SST analogs (PTP)?

A
  1. PTP activation dephosphorylates signaling molecules that promote cell division.
  2. This reduces mitogen-activated protein kinase (MAPK) activity, leading to a decrease in proliferation markers like Ki-67 and inducing cell cycle arrest.
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23
Q

What are the anti-proliferative and growth-inhibitory effects of the SST analogs (Atk pathway inhibition)?

A
  1. Upregulation of p21 and p27 (cell cycle inhibitors), resulting in cell cycle arrest.
  2. Downregulation of Zac1, a transcription factor that promotes growth, further inhibiting cell proliferation.
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24
Q

What is the induction of apoptosis action of SST analogs?

A

Increase caspase-8 activity, promoting programmed cell death (apoptosis)

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25
What is the anti-angiogenesis action of SST analogs?
Reduced VEGF production decreases blood vessel formation, suppressing the tumor's abilty to grow and spread
26
What is the PK of Octeoride?
Subcutaneous x2 daily, half-life of about 90 minutes, duration of action is about 12 hours
27
If Octeoride is given IM, how often should it be given?
Long-acting, slow-release form, given once every 4 weeks
28
What receptors does Octeoride bind to?
SST2 > SST5 > SST3 but not SST1
29
What are the therapeutic uses of Octeroride?
1. Decreases GH synthesis in acromegaly 2. Main therapy: neuroendocrine tumors or carcinoids 3. Decreases tumor size but it is reversed when treatment stops
30
What is Lenreotide?
Long-acting octapeptide SST analog Available in prefilled syringes
31
What receptors does Lanreotide bind to?
SST2 > SST5
32
What are the PK of Lanreotide?
Deep SubQ injection (every 4 weeks) - prolonged suppression of GH secretion Efficacy comparable to Octeoride
33
What is Pasireotide?
Long-acting cyclo-hexapeptide SST analog
34
What receptors does Pasireotide bind to?
Binds to multiple SST receptors (1, 2, 3, and 5) and the highest affinity for SST5 receptor
35
What are the therapeutic uses of Pasireotide?
Approved treatment of Cushing disease and acromegaly
36
What are other therapeutic uses of SST analogs?
1. Block growth factors and cytokines are used for the treatment of symptoms associated with metastatic carcinoid tumors (flushing and diarrhea) and adenomas secreting VIP 2. Octeoride and Lanreotide --> thyrotrope adenomas that over-secrete TSH (failed surgery) 3. Octeoride --> treatment of acute variceal bleeding and for perioperative prophylaxis in pancreatic surgery
37
What are the adverse effects of SST analogs?
1. GIT: diarrhea, nausea, abdominal pain, flatulence, steatorrhea 2. Asymptomatic cholesterol gallstones (during long-term treatment) 3. Bradycardia and QT prolongation - in patients with underlying cardiac disease 4. Hypothyroidism 5. Hypocorticolism
38
How is hypocorticolism an adverse effect of SST analogs?
Pasireotide suppresses ACTH secretion --> decreases cortisol secretion --> hypocortisolism
39
How are asymptomatic gallstones an adverse effect of SST analogs?
Inhibition of gallbladder emptying, hepatic bile secretion, and sphincter motility, as well as modification of bile composition --> gallstonestasis
40
What is Pegvisomant?
A modified version of GH (mutated-inactive/recombinant protein) bound to PEG polymers A highly sensitive antagonist of growth hormone receptor
41
What is the MOA of Pegvisomant?
1. Binds to the GHR with high affinity at binding site one and blocks the binding of endogenous GH to GHR 2. Does not activate downstream JAK/STATsignaling or stimulate IGF-1 secretion
42
What are the PK of Pegvisomant?
Administered SubQ The dose is titrated at 4 to 6-week intervals based on serum IGF-1
43
When can Pegvisomant be gievn weekly?
When IGF-1levels are not fully controlled
44
What are the contraindications of Pegvisomant?
1. Should not be used in patients with an unexplained elevation of hepatic transaminases --> Liver function should be monitored in all patients
45
What are the concerns that are associated with Pegvisomant?
Loss of negative feedback by GH and IGF-1 may increase the growth of GH-secreting adenomas --> careful follow-up by pituitary MRI is recommended
46
What are the common adverse effects of Pegvisomant?
Pain Arthralgia Fever Chills Body aches Flu symptoms Nausea Diarrhea GI discomfort Dizziness Skin reaction Abnormal liver function tests Pain or irritation where the medicine was injected GH increases gluconeogenesis
47
What are clinically significant adverse effects of GHR agonists?
Systemic hypersensitivity Lipohypertrophy at injection sites Hypoglycemia in diabetes
47
What is the MOA of dopamine agonists?
1. Activation of D2 dopamine receptors 2. Suppression of PRL production and relief of the inhibitory effect of hyperprolactinemia on ovulation (useful in prolactinoma treatment)
48
What kind of treatment options are dopamine agonists?
Initial treatment of choice --> Surgery and radiation are reserved for patients who either do not respond or are intolerant of DA receptor agonists
49
What are examples of Dopamine agonists?
Bromocriptine Cabergoline Quinagolide
50
What is Bromocriptine?
A semisynthetic ergot alkaloid
51
What is the MOA of Bromocriptine?
Interacts with D2 receptors --> inhibits release of PRL Also activates D1 dopamine receptors to a lesser extent
52
What are the effects of Bromocriptine?
Normalizes serum PRL levels in 70 to 80%, decreases tumor size in more than 50% of patients with prolactinoma Hyperprolactinemia and tumor growth recur on cessation of therapy in most patients
53
What are the clinical uses of Bromocriptine?
To prevent lactation, treat galactorrhea due to excessive prolactin secretion Treat prolactin-secreting pituitary tumors Treatment in Parkinsonism and acromegaly
54
What are the PK of Bromocriptine?
Well absorbed orally, extensive first-pass metabolism May be administered vaginally, with fewer GI side effects
55
What are the adverse effects of Bromocriptine?
More commonly nausea and vomiting, headache, and postural hypotension on initial use Less frequently: nasal congestion, digital vasospasm, CNS effects
56
What are examples of CNS effects due to Bromocriptine?
Psychosis, nightmares, and insomnia
57
What is Cargoline (Dostinex)?
Ergot derivative
58
What are the PK of Cabergoline compared to Bromocriptine?
Has a longer half-life, higher affinity, and a greater selectivity for the D2 receptor Undergoes significant first-pass metabolism in the liver
59
In higher doses what is Cabergoline useful for as a treatment?
Useful in acromegaly at higher doses, alone or in combination with SST analogs
59
Why is Cabergoline the preferred drug for the treatment of hyperprolactinemia?
Greater efficacy but fewer side effects Induces remission in a significant number of patients with prolactinomas
60
What are the adverse effects of Cabergoline?
Nausea Hypotension Dizziness Linked to valvular heart disease, possibly due to its agonist activity at 5HT2B receptors
61
What is Quinagolide?
Non-ergot D2 receptor agonist
62
What is the half-life of Quinagolide?
22 hours
63
What are the contraindications of Quinagolide?
Not to be used when pregnancy is intended
64
How often is Quinagolide administered?
Once daily
65
What are tocolytic drugs?
Drugs to suppress uterine contractions
66
What is the aim of tocolytic drugs?
Prolong and delay gestation in patients, inhibition of acute preterm labor
67
What are examples of tocolytic drugs?
NSAIDs Ca2+ channel blockers Beta-androgenic agonists Oxitocyn inhibitors
68
What is an example of Oxytocin inhiboitors?
Atosiban, widely used in Europe but is not FDA-approved in the US
69
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Endocrine System (25 decks)

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