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Endocrine, Genetics, Male Repro > Pharmacology-Androges:Anti-Androgens > Flashcards

Pharmacology-Androges:Anti-Androgens Flashcards

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1
Q

Major source of androgen in women

A

Zona reticularis makes 50% and ovaries make 50%, minor source in men (5%)

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2
Q

Main steroid hormone produced by zona reticularis?

A

DHEA. Androstenedione, androstenediol, and testosterone are made in minor amounts

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3
Q

What happens as a result of the pulse secretion of GnRH by the hypothalamus?

A

Anterior pituitary releases FSH and LH -> FSH stimulates spermatogenesis. LH stimulates Leydig cells to release testosterone -> testosterone completes stimulation of spermatogenesis.

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4
Q

What effect does testosterone have on cells that are only responsive to DHT?

A

It enters the cell and is reduced to DHT by 5-alpha reductase. Then DHT binds to androgen receptors causing them to dimerize. The complex then goes to the nucleus and turns genes on.

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5
Q

What are the effects of testosterone in growth and development?

A

Internal genitalia development (Wolffian development), skeletal muscle growth, deepens voice, erythropoiesis and bone.

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6
Q

What are the effects of DHT in growth and development?

A

External genitalia development and hair follicle stimulation

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7
Q

What are the effects of estradiol in growth and development?

A

Conversion of testosterone to estradiol by the aromatase is responsible for closure of epiphyseal plates.

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8
Q

Why can’t you take testosterone orally?

A

Normally it is inactivated by first pass liver metabolism and modified oral androgens at the 17alpha position can evade liver deactivation but have liver toxicity. These are also too weak to stimulate spermatogenesis.

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9
Q

What type of modification do we do to injectable androgens?

A

Fatty acids are esterified to 17beta position to prolong absorption after IM injection

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10
Q

What is the drug that you only inject 2x a month for testosterone replacement therapy?

A

Testosterone enanthate, modified at 17beta position

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11
Q

Nobody likes to get testosterone shots. What can you give instead of testosterone enanthate?

A

Testoderm patch (on scrotum), androderm patch (can be placed anywhere), androgel (rub on shoulders), testosterone buccal system and topical testosterone solution (like deodorant).

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12
Q

Clinical uses of androgens

A

Hypogonadism (LH/FSH), mutilated testicles, andropause (testosterone supplement), wasting states (HIV), hereditary angioedema, anemia (rarely).

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13
Q

Clinical uses of hydrocortisone or fludrocortisone in men?

A

CAH (21-hydroxylase deficiency): DHEA excess from lack of negative feedback by glucocorticoids can cause precocious puberty in males and virilization in females. Giving cortisol will feedback inhibit ACTH release by the hypothalamus and slow androgen production.

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14
Q

What clinical use of androgens prefers the orally active 17alpha alkylated androgens?

A

Hereditary angioedema. This is an AD disease where the 1st component of the complement cascade is low, complement is overactive and increases permeability of blood vessels causing angioedema. Danzol or stanozolol stimulates the synthesis of hepatic esterase inhibitor and can treat the condition if taken long term.

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15
Q

Adverse effects of androgen therapy?

A

Transfer of androgens to children, precocious puberty in children, virilization in women and jaundice w/orally active forms. Additionally, decreased libido, impotence, testicular atrophy, gynecomastia.

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16
Q

What is the pathophysiology behind testicular atrophy with steroid abuse? Gynecomastia?

A

Testicular atrophy: FSH & LH are inhibited by the exogenous steroids. Gynecomastia: CYP19 aromatize in liver converts testosterone to estrogen. Note that some abusers take tamoxifen with steroids to prevent gynecomastia.

17
Q

When would you use anti-androgens?

A

Virilization prevention and BPH reduction

18
Q

How does leuprolide work?

A

It is a GnRH agonist with stimulates continuous secretion of GnRH which causes regression of GnRH receptors in the anterior pituitary. This reduces FSH and LH secretion which will decrease testosterone production by the testis.

19
Q

GnRH receptor antagonist used to treat BPH

A

Abarelix, prevents GnRH activation of GnRH receptor in pituitary and prevents excess release of LH and FSH, reducing testosterone production by the testis.

20
Q

Anti-androgen used in hirsutism in women?

A

Cyproterone acetate: antagonist at the androgen receptor AND an agonist at the progesterone receptor.

21
Q

Competitive androgen receptor antagonists used for metastatic prostate cancer?

A

Flutamine (hepatotoxic), bicalutamide (less toxic) and enzalutamide (best).

22
Q

This drug blocks 5alpha-reductase type II in treatment of BPH?

A

Finasteride (testosterone is still able to keep muscle mass up) shrinks prostate size

23
Q

This drug blocks 5alpha-reductase types I and II in all tissues for BPH treatment?

A

Dutasteride shrinks prostate size

24
Q

How can we let the urine flow in patients with urinary hesitancy due to BPH?

A

Alpha1 adrenergic receptor antagonists (tamsulosin is only alpha1a antagonist, used in normotensive patients) and 5alpha-reductase inhibitors used in combination.

25
Q

Floppy iris syndrome

A

Tamsulosin therapy for a long time causes floppy iris due to alpha1a receptor inhibition on the iris, this complicates cataract surgery.

26
Q

What drug may be used to treat male pattern baldness? What’s the side effect?

A

Finasteride. This is because DHT mediates male pattern baldness, but lack of DHT caused ED in 2% of patients

27
Q

Drugs used to treat erectile dysfunction

A

Sildenafil (PDE5-I = cGMP is not broken down), alprostadil (PGE1 analogue = increased cAMP), papaverine (nonselective PDE-I = cGMP and cAMP are not broken down) and phentolamine (alpha-1 adrenergic receptor antagonist = no vasoconstriction in penis) all relax nonvascular smooth muscle cells in the corpora cavernosa.

28
Q

Why is sildenafil most popular for ED?

A

All the others are injected straight into the penis

29
Q

How does sildenafil cause erection?

A

ACh binds M3 -> PLC -> Increased Ca -> NO production -> Activation of guanylyl cyclase -> cGMP -> Sildenafil inhibits PDE-5 breakdown of cGMP -> PKG activity increased -> Phosphatase activated -> Actin & myosin relax -> corpora cavernosa fills with blood -> erection

30
Q

Side effects of sildenafil

A

Severe hypotension w/nitrates, priapism (treat w/EPI) and 50% greater risk of malignant melanoma

31
Q

Other sites affected by PDE5 inhibitors

A

Prostate (alleviates BPH symptoms) and lungs (alleviates pulmonary HTN)

32
Q

Genetic problems we can’t treat with androgens or anti-androgens

A

Pseudohermaphroditism (lack of 5alpha reductase) and testicular feminization (androgen binding site doesn’t work)

Endocrine, Genetics, Male Repro (36 decks)

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