Male Reproductive Pharmacology Flashcards Preview

Reproductive System > Male Reproductive Pharmacology > Flashcards

Flashcards in Male Reproductive Pharmacology Deck (29)
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1
Q

What enzyme converts Testosterone to Dihydrotestosterone?

What enzyme converts Testosterone to Estradiol?

A
  • What enzyme converts Testosterone to Dihydrotestosterone?
    • 5α-reductase
  • What enzyme converts Testosterone to Estradiol?
    • Aromatase
2
Q

Where are the two types of 5α-reductase found?

A
  • Type I
    • predominantly in non-genital skin, liver and bone
  • Type II
    • predominantly in urogenital tissue in men and genital skin in men and women
3
Q

What are the main functions of DHT?

Which receptor does it use?

A
  • What are the main functions of DHT?
    • Development of external genitalia
    • Primary androgen in the prostate and in hair follicles
      • Causes balding and prostate hyperplasia
  • Which receptor does it use?
    • Androgen receptor
4
Q

What are the main functions of Testosterone?

Which receptor does it use?

A
  • What are the main functions of Testosterone?
    • Development of internal genitalia
    • Primary androgen in skeletal muscle
    • Involved in erythropoiesis
  • Which receptor does it use?
    • Androgen receptor
5
Q

What are the main functions of Estradiol?

Which receptor does it use?

A
  • What are the main functions of Estradiol?
    • Involved in closing of the epiphyses
    • Bone density
    • Libido
  • Which receptor does it use?
    • Estrogen receptor
6
Q

What are two mechanisms by which androgens can have varying actions in different tissues?

A
  1. High affinity of DHT binding to the receptor compared to testosterone
  2. Tissue-specific transcription factors
7
Q

Why are most androgen preparations designed to bypass the liver?

A

Testosterone has a high first pass effect

8
Q

How are testosterones delivered?

A

Transdermal patches

Gels

Buccal tablet

9
Q

How are testosterone esters (Cypionate) different than testosterone?

What effect does this have on their release?

A

A fatty acid is esterified to the 17-hydroxyl group to create a lipophilic analog - this results in slow testosterone release

10
Q

What is a 17-α alkylated compound? (give an example)

What risks are associated with their use?

A
  • What is a 17-α alkylated compound? - Stanozolol
    • Testosterone with an alkyl group added to the 17 position - slowed hepatic catabolism
  • What risk is associated with their use?
    • May cause hepatotoxicity, cholestasis, and blood filled hepatic cysts – in large amounts may lower HDL cholesterol
11
Q

Which type of testosterone preparation corresponds to the following kinetic profile?

A

Testosterone Gel

12
Q

What is the principal indication for androgen therapy?

A

Male hypogonadism (due to testosterone deficiency)

13
Q

What is the goal in androgen therapy?

What are some adverse effects associated with androgen therapy?

A
  • What is the goal in androgen therapy?
    • To mimic normal serum testosterone concentrations
  • What are some adverse effects associated with androgen therapy?
    • Similar to those that occur during puberty; acne, gynecomastia, and more aggressive sexual behavior
14
Q

What are some non-FDA approved uses of androgens?

A
  • Male senescence (males whose serum levels are low due to age)
  • Women with low serum testosterone
  • Treatment of muscle wasting associated with AIDS
  • Blood dyscrasias
  • Improvement of athletic performance
15
Q

Besides hypogonadism what other FDA approved uses exist for 17-alkylated androgens?

Stanozolol:

Danazol:

A
  • Stanozolol:
    • Angioedema - stimulates hepatic synthesis of esterase inhibitor
  • Danazol:
    • Treatment of endometriosis and fibrocystic breast disease
16
Q

Older men receiving testosterone therapy have a twofold increase in relative risk of ______ ______

A

myocardial infarctions

17
Q

How would you deliver androgen therapy to a male who has not yet reached puberty (no closure of epipyseal plates)?

A

Treat them with GH before their hypogonadism is treated with testosterone

18
Q

What are “weak androgens”?

A

Testosterone precursors (androstenedione and DHEA) are considered weak androgens and were treated as nutritional supplements before the FDA warned manufacturers to stop

19
Q

What are the adverse effects of androgen abuse?

A
  • Decreased endogenous testosterone and sperm production leading to decreased fertility
  • Decreased testicular size
  • High doses cause erythrocytosis
  • Gynecomastia (from testosterone converted to estrogen)
  • Virilization in women and children (hirsutism, hair loss)
  • Phallic/clitoral enlargement
20
Q

Which androgen does not cause gynecomastia and why?

A

Dihydrotestosterone - Androgens with a modified A-ring cannot be aromatized

21
Q

What are the three classes of drugs (and an example of each) that inhibit androgen secretion?

A

GnRH analogs - Leuprolide

5α reductase inhibitors** - Finasteride**

Androgen receptor antagonist - Flutamide

22
Q

**Leuprolide **(GnRH analog)

  • Mechanism of action:
  • Therapeutic use:
  • Side effects:
A
  • Mechanism of action:
    • **Inhibits testosterone secretion by inhibiting LH secretion **- causes transient stimulation of gonadotropin secretion but then down-regulates GnRH receptor
  • Therapeutic use: Advanced prostate cancer, endometriosis, central precocious puberty
  • Side effects: Hot flashes, decreased bone density, vaginal dryness/atrophy, erectile dysfunction
23
Q

**Flutamide **(Androgen antagonists)

  • Mechanism of action:
  • Therapeutic use:
  • Side effects:
A
  • Mechanism of action: Nonsteroidal competitive inhibitor of the androgen receptor (limited efficacy because they increase LH secretion)
  • Therapeutic use: Metastatic prostate cancer and hirsutism in women (off label)
  • Side effects: Galactorrhea, breast tenderness, gynecomastia, hot flashes, impotence, libido decrease, tumor flare, **hepatic failure **
24
Q

**Finasteride **(5α reductase inhibitor)

  • Mechanism of action:
  • Therapeutic Use:
  • Side Effects:
A
  • Mechanism of action: blocks the conversion of testosterone to dihydrotestosterone
  • Therapeutic Use: Prostate hyperplasia and male pattern baldness
  • Side Effects: Impotence and decreased libido
25
Q

What types of drugs are used to treat erectile dysfunction?

A
  • PDE5 inhibitors (Sildenafil, Vardenafil, Tadalafil)
  • PGE1 analogs (Alprostadil)
26
Q

Alprostadil

  • Administration:
  • Mechanism of Action:
  • Side effects:
A
  • Administration: Intracavernus injection or urethral suppository
  • Mechanism of Action: PGE1 causes dilation of cavernosal arteries (erections last 1-3 hours)
  • Side effects: penile pain and urethral burning
27
Q

How does nitric oxide cause erection and how is this process activated by PDE5 inhibitors?

A

Nerves and vascular endothelial cells in the corpus cavernosum produce NO during sexual arousal which stimulates formation of cGMP that relaxes the smooth muscle of the corpus cavernosum and penile arteries → engorgement
**PDE5 metabolizes cGMP and is blocked by PDE5 inhibitors **(increases cGMP accumulation)

28
Q

Which of the PDE5 inhibitors has the longest duration of activity? (AKA: the “weekend” drug)

A

Tadalafil

29
Q

What are the side effects of PDE5 inhibitors?

When are they contraindicated?

A
  • What are the side effects of PDE5 inhibitors?
    • Headaches, flushing, visual disturbances
  • When are they contraindicated?
    • Contraindicated in patients taking **nitrates - **extreme hypotension