Pharmacology of androgens and antiandrogens Flashcards

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1
Q

Where are androgens secreted from?

A

testes, ovaries, adrenal cortex, adipose tissues (LITTLE BIT)

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2
Q

In the testes, what cels secrete testosterone?

A

Leydig cells

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3
Q

What are the 3 regions of the adrenal cortex and what do they secrete?

A

zona glomerulosa: mineralocorticoid secretion (aldosterone)
zona fasciculata: cortisol secretion
zona reticularis: androgen secretion

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4
Q

What are the 2 cell types in testes?

A

Leydig

Sertoli

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5
Q

What are the leydig cells and sertoli cells under the influence of?

A

Leydig- LH

Sertoli- FSH

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6
Q

Leydig cells release testosterone. What is the role of testosterone?

A
  1. stimulates sertoli cells for spermatogenesis

2. converted to DHT

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7
Q

What does FSH do?

A

act on sertoli cells:
spermatogenesis
releases AMH
release inhibin- inhibits FSH release from pituitary

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8
Q

What happens if there are no testosterone receptors in the body?

A

no negative feedback so high testosterone levels
high FSH and LH levels
no testosterone effects- so no male characteristics seen

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9
Q

What are the precursors of testosterone?

A

androstenedione and androstenediol

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10
Q

What does testosterone get metabolized to?

A
  1. androsterone and etiocholanolone
  2. dihydrotestosterone= under influence of 5 alpha reductase
  3. oestrogen= through aromatase
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11
Q

Can DHT be converted to oestrogen?

A

NO BITCH

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12
Q

Testosterone is converted to DHT in all cells except what?

A

muscles

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13
Q

What is testosterone converted to DHT by?

A

5 alpha reductase

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14
Q

What does DHT do?

A

external virilisation
sexual maturity at puberty
growth of prostate and penis at puberty
causes facial hair, acne, and temporal hairline recession particularly in males
hairline recession usually leads to more hair growing elsewhere

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15
Q

How can we treat prostate cancer?

A

prostate grows bc of DHT

so give 5 alpha reductase inhibitors

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16
Q

How to treat male baldness

A

DHT causes loss of hair

so give 5 alpha reductase inhibitors

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17
Q

There are 2 isotopes of enzyme 5 alpha reductase. What are they?

A

type 1: scalp and skin

type 2: genital skin and prostate

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18
Q

What happens with 5 alpha reductase deficiency?

A
AUTOSOMAL RECESSIVE
testes can develop but NO PROSTATE
FEMALE external genitalia
puberty clitoris can enlarge
at puberty with the testosterone rise, if testosterone receptors are there you can develop external male genitalia
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19
Q

What is male pseudo hermaphrotidism?

A

type 2 5 alpha reductase mutation
primary sexual characteristic different to secondary sexual characteristic
fertile (can be father) but female external genitalia

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20
Q

If DHT is not metabolised properly, what happens?

A

prostatic hyperplasia
this is when DHT is not metabolized completely, and thus there will be enlargement of the prostate
there may also be acne and hirsutism (excess hair)

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21
Q

What secondary characteristics are DHT and testosterone responsible for?

A
tall height
more muscle
deep voices- more larynx growth
external virilisation
more body hair
more muscle bulk
less subcutaneous fat so subcutaneous veins become more prominent
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22
Q

Give some names of androgens:

A

testosterone, nandrolone, oxymetholone, stanozolol

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23
Q

What is oxymethalone used for?

A

sold as anapolon or anadrol

treatment of anemia

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24
Q

What are the side effects if you abuse anabolic steroids?

A

hypertension and edema
cholestatic jaundice
SUPPRESS LH and FSH- smaller testicular size
premature closure of long epiphyseal bones
gynecomastia
increase muscle mass
acne
more agression
more LDL, less HDL- more vascular disease

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25
Q

What are the 2 main reasons for the development of internal and external genitalia to fail?

A

androgen insensitivity syndrome

21 hydroxylase deficiency

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26
Q

What happens in androgen insensitivity syndrome?

A

androgen is present but receptor isnt bc mutation in receptor

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27
Q

What are the symptoms of AIS?

A

XY with female genitalia
short vaginal length
testes in abdomen
no female internal genitalia

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28
Q

How is AIS treated?

A

remove testes
put patient on oestrogen therapy at puberty
if mild with male external genitalia give high testosterone
the patient is then assigned to the gender on which they feel more confortable

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29
Q

What is 21 hydroxylase deficiency?

A

congenital adrenal hyperplasia

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30
Q

What happens in CAH?

A

21 HYDROXYLASE makes mineralocorticoids, or glucocorticoids from progestogen
if deficient, progestogens build up
then get converted to testosterone

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31
Q

What are the symptoms of CAH?

A

females:
ambiguous genitalia
feminised testes
internal genitalia both male and female

males:
premature puberty

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32
Q

What is an example of synthetic GnRH?

A

gonadorelin

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33
Q

What are examples of GnRH analogues?

A

buserelin

goserelin

34
Q

What do GnRH analogues do?

A

desensitize the receptors for GnRH after an initial surge of LH and FSH release and then act as antagonists
cause a reduction in testosterone in the long term
they are useful for prostate and breast cancers and endometriosis

35
Q

What does a GnRH antagonist do?

A

is a competitive antagonist of the GnRH receptor on the pituitary
these negatively affect the pituitary
cause no initial surge of LH and FSH
use in IVF
prevent women having an LH surge and thus help with breast cancer

36
Q

What is an example of an androgen antagonist?

A

cyproterone

37
Q

What is cryptorchidism?

A

failure of testes to descend

38
Q

What can cryptorchidism cause?

A

infertility

tumour

39
Q

What are the treatment of mild AIS?

A

High dose testosterone

40
Q

What are the treatment for strong AIS?

A

OESTROGEN

41
Q

What does mesterolone (methyltestosterone) do?

A

treats male infertility associated with hypogonadism

42
Q

What does the drug danazol treat?

A

gynaecomastia
mastalgia (breast pain)
benign fibrocystic disease (breast tenderness)
endometriosis and infertility
menorrhagia (increased/heavy and prolonged menstrual bleeding)

43
Q

What is danazol?

A

androgen derivative
it does not get converted to oestrogen
has antioestrogenic and antiprogestogenic effects

44
Q

How does danazol work?

A

it inhibits the release of LH and FSH

45
Q

What is a primary hypogonadal syndrome?

A

testes fail to produce adequate testosterone in response to LH

46
Q

What is an example of hypogonadal syndrome?

A

Klinefelter’s syndrome (XXY)

47
Q

What is Klinefelter’s syndrome?

A

XXY
deficient –ve feedback at the HPG axis bc of low testosterone
so have high FSH and LH

48
Q

What is the treatment of Klinfelter’s syndrome?

A

GH
testosterone
will take 2 years to reach puberty
growth hormone and testosterone, and it will take 2 years to reach puberty

49
Q

What is a secondary hypogonadal syndrome?

A

deficiency in the pituitary hormones (FSH and LH)

OR pituitary dysfunction

50
Q

What is an example of secondary hypogonadal syndrome?

A

Kallmann’s syndrome
leads to delayed/absent puberty
if untreated- lead to infertility

51
Q

How do you treat kallman’s?

A
give gonaderelin (synthetic GnRH)
give LH or FSH
52
Q

What is precocious puberty?

A

early puberty

53
Q

How do you treat precocious puberty?

A

androgen antagonists
the drug is: cyproterone acetate
mechanism: inhibits peripheral androgen receptors

54
Q

How can you treat a sex offender?

A

androgen antagonist with their consent

55
Q

What is guserelin and boserelin?

A

GnRH analogue agonists
when they are administered to reduce FSH and LH levels, there is an initial LH and FSH surge
bc of this there is increase in testosterone in the body
can use cyproterone to lower LH, FSH and testosterone levels

56
Q

What can cyproterone be used for?

A

acne
hirsutism
loweing FSH and LH and testosterone
treat precocious puberty

57
Q

What does benign prostatic hypertrophy mean?

A

enlarged prostate in older men

causes urinary obstruction

58
Q

Where is the prostate located between?

A

bladder and penis

59
Q

How does BPH cause urinary obstruction?

A

urethra passes from bladder to penis through the centre of the prostate through the penis
the prostate enlargement causes urinary obstruction
can lead to pain and infection bc of the stagnated urine

60
Q

How do you treat BPH?

A

5 alpha reductase inhibitor- finasteride

alpha 1 adrenergic blockers eg tamsulosin and alfuzosin

61
Q

Give two examples of drugs that are 5 alpha reductase inhibitors?

A
finasteride = it inhibits type II 5 alpha reductase
dutasteride = inhibits both type I and type II
reductases = SO CANT USE FOR BPH
62
Q

How does alpha 1 adrenergic blockers help with BPH?

A

help relax smooth muscle components of the prostate

63
Q

What is the main way to treat prostatic cancer?

A

DHT and Testosterone grow prostatic cells

treatment needs to focus on reducing this

64
Q

How do you treat prostatic cancer?

A

cyproterone acetate
GnRH analogues such as goserelin and buserelin
GnRH antagonists such as cetrorelix and ganirelix
oestrogens such as ethinyloestradiol and diethylstilbestrol
orchidectomy (castration)
anti-androgens such as flutamide
5 alpha reductase inhibitors such as finasteride and dutasteride

65
Q

What does cyproterone acetate do?

A

an androgen antagonist

it will inhibit peripheral androgen receptors

66
Q

What do GnRH analogues do?

A

it can be given continuously to suppress Leydig cell function •
this happens because the GnRH analogue will desensitize GnRH receptors and thus FSH and LH levels will reduce
thus testosterone levels reduce

67
Q

What do GnRH antagonists do?

A

block LH and FSH release
leydig cells regression
testosterone reduces

68
Q

Why is orchidectomy good for helping prostate cancer?

A

if you remove the testes, then you will not produce much testosterone so possibly no prostate cancer

69
Q

How does anti androgen help with prostate cancer?

A

compete with testosterone and DHT

block their action

70
Q

What is erectile dysfunction?

A

consistent inability to sustain an erection of sufficient rigidity for sexual intercourse

71
Q

Who can get erectile dysfunction?

A

40-70 year old men
nerve damage
endocrine disease
depression

72
Q

What is the pathway for eretction?

A
  1. stimulations: mechanoreceptors on the penis respond to touching, stroking of penis. There are also thoughts, sights, smells which trigger the CNS
  2. these signals go to neurons in penis
  3. get an increase in parasympathetic NO activity and decrease in sympathetic activity
  4. NO has vasodilating effect
  5. blood fills in corpus cavernosum
  6. erection
  7. bc of erection, veins in the penis compress. this leads to more filling up of blood in the penis.
73
Q

What would sympathetic activity do?

A

constrict arteries in the penis

74
Q

People with erectile dysfunction produce less what?

A

NO

75
Q

What do you treat erectile dysfunction with?

A

PDE5 inhibitors= SILDENAFIL, TADALAFIL, VARDENAFIL

76
Q

What is the mechanism for PDE5 inhibitors?

A

NO activates guanylate cyclase which re
leases cGMP from GTP
cGMP is produced in the smooth muscles of the penis which
modulates Ca2+ entry into the sarcoplasmic reticulum thus
making less Ca2+ available (by activation of protein
kinases)
this leads to relaxation of the smooth muscle
however, cGMP is broken down by PDE5 which removes its effect
PDE5 inhibitors act by inhibiting PDE5 thus making the effects of cGMP last longer
it blocks cGMP hydrolysis by taking its active s
ite on the PDE5 enzyme

77
Q

What are side effects of PDE5 inhibitors?

A

headache, vasodilation, flushing, reduction in BP, disturbances
of colour vision due to inhibition of PDE6 in retina
sometimes priapism, which is painful erections that do not go away

78
Q

Why shouldn’t PDE5 inhibitors be taken with nitrates?

A

BOTH PDE5 inhibitors and nitrates = vasodilators

if take together- big blood pressure fall

79
Q

If patient has angina pectoris and takes PDE5 inhibitors and nitrates, what can happen?

A

heart attack
because patients with angina require a higher than
normal blood pressure to perfuse the heart
if bp drops heart no get enough oxygenated blood= MI

80
Q

What do sertoli cells release?

A

AMH= regresses mullerian duct in utero

Inhibin B= acts on anterior pituitary to reduce FSH release

81
Q

What type of hormone is testosterone?

A

steroid so it diffuses through and binds to its receptor in the cytosol