Pharmacology: Sex steroid hormones Flashcards

1
Q

How are sex hormones transported in the blood?

A

98% bound to sex hormone binding globulin, this protects from hepatic metabolism
They are stored in fatty tissue eg adipose and brain due to lipophilic properties which increases T1/2

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2
Q

Outline the enterohepatic recirculation of oestrogen

A

Orally administered oestrogens pass from gut to liver and are conjugated with glucuronide and passed into bile.
Bile enters small intestine where oestrogens are unconjugated by bacteria - oestrogen re-enters blood stream
Oral antibiotics affect this by reducing gut flora

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3
Q

How does steroid receptor expression change through the menstrual cycle?

A

The receptors change dependent on the influencing hormone eg receptors for oestrogen are highest at ovulation and receptors for progesterone are highest in the secretory phase.

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4
Q

What are the major effects of oestradiol?

A
  • stimulates growth of endometrium
  • stimulates breast growth
  • stimulates production of progesterone receptor
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5
Q

What are the major effects of progesterone?

A
  • stimulates growth of endometrium
  • stimulates breast growth
  • maintains pregnancy
  • inhibits production of oestrogen receptor
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6
Q

What are the major effects of testosterone?

A
  • stimulates body hair
  • deepens voice
  • anabolism
  • aggression
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7
Q

What are the actions of prescribed oestrogen?

A

Actions: sodium and water retention, raises HDL and lowers LDL, decreases bone reab, increases blood coag, impairs glucose tolerance.

Side effects: breast tenderness, nausea, water retention, thromboembolism (PE is life threatening)

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8
Q

What are the actions and side effects of prescribed progestin?

A

Actions: increases bone mineral density, mood changes (forgetful), maintains pregnancy, secretory endometrium

Side effects: weight gain, acne, depression, lack of conc, nausea

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9
Q

What are the metabolic affects of testosterone?

A

Adversely affects lipid profiles - reducing HDL and increasing LDL, therefore increased risk of athersclerotic disease (and therefore heart disease) in males and gender reassigned females.

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10
Q

How does the COCP work?

A

Prevents ovulation due to the moderate progestin dose.

Secondary actions are reducing endometrial receptivity to implantation and thickens cervical mucus.

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11
Q

How does the POP work?

A

Lower dose of progestin and therefore does no inhibit ovulation but thickens cervical mucus as the primary action. Can be used when the COCP is contraindicated eg over 35, smoker, migraines

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12
Q

List some names of oral synthetic oestrogens

A

Ethinylestradiol (cocp) , mestranol (cocp and HRT), valerate (cocp and HRT)

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13
Q

List some names of oral synthetic progestins

A

Medroxyprogesterone (HRT)

Dyhydroprogesterone (contraceptive)

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14
Q

List some names of oral synthetic testosterones

A

Norethisterone
Norgestrel
Ethynodiol

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15
Q

How does oestrogen exert its effects in the cell?

A

Oestrogen enters the cell and binds to its receptor and the receptor comes together with another receptor then the dimer makes nucleus produce mRNA to produce proteins.
There are multiple oestrogen activated genes and therefore the effects vary widely

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16
Q

What are the adverse effects of oral contraceptives?

A
  • venothromboembolism is the major risk
  • MI is closely second
  • hypertension
  • decreased glucose tolerance
  • increase stroke risk in women with focal migraine
  • headaches
  • cholestatic jaundice
  • increase incidence of gallstones
    (last 2 are because there is increased HDL so more cholesterol taken to gallbladder, also progesterone constricts the bile duct)
17
Q

What antibiotics cannot be taken with oral contraceptives?

A

Many are metabolised by cytochrome P450 (hepatic)
(very important to remember)
and therefore drugs that induce this enzyme eg rifampicin, rifabutin, affect the pharmodynamics

18
Q

What are the main classes of progestins?

A

C-21 progestins
19-nor testosterones
Progestins based on spironolactone

19
Q

What type of progesterone is given in the progesterone depot?

A

MPA is in provera and given every 12 weeks

MPA also used in paedophiles to block libido

20
Q

What type of progesterone is given in the implant?

A

Etonogesterol is in nexplanon

21
Q

What are the types of emergency contraception?

A

Levonelle can be used 72hrs post-coitus - contains 1.5mg progestin
EllaOne can be used 120hrs post-coitus - contains 30mg progestin (note difference in dose)
Copper IUD can be used 120hrs post-coitus - copper is toxic to blastocyst so prevent implantation

22
Q

What is the difference between ERT and HRT?

A
ERT = oestrogen only replacement therapy
HRT = oestrogen and progesterone (but technically insulin for diabetics is also HRT)
23
Q

Why is HRT prescribed?

A
  • symptomatic relief eg hot flushes, vaginal dryness
  • protective against osteoporosis
    (NB does not prevent heart disease)
24
Q

What are the risks and benefits of HRT?

A
  • unopposed oestrogen (ERT) increases risk of endometrial and ovarian cancers as they are oestrogen receptive
  • opposed oestrogen (HRT) increases risk of breast cancer
  • also increased risk of stroke
  • beneficial in ischaemic heart disease due to changes in lipid profile, but not effective in overweight
  • risk of thromboembolism
25
Q

Give some examples of oestrogen inhibitors and their uses

A

Clomiphene: inhibits oestrogen binding to its receptor in the anterior pituitary so inhibits negative feedback. FSH and LH increased so induces ovulation (used a lot in IVF)

Tamoxifen: binds to oestrogen receptor in breast tissue and blocks myoepithelial cell division so reduces risk of breast cancer for years then increases risk after that. Also induces ovulation

26
Q

Give an example of an anti-progestin and its use

A

RU486 - partial agonist to progesterone receptor so partially inhibits progesterone action.
Makes the uterus more sensitive to prostaglandins so used for pregnancy termination and occasionally induction of labour

27
Q

Give an example of an anti-androgen and its use

A

Cyproterone - partial agonist at the progesterone receptor so competes with the most potent testosterone (dihydrotestosterone)
Used in COCP instead of progestin

28
Q

Give an examples of a SERM and its effect?

A

SERM = selective oestrogen receptor modulator

Raloxifene - protects against osteoporosis. Has oestrogenic effects on bone, lipid profile and blood coag.
NO proliferative effects on endometrium and breast so reduced risk of cancer.

29
Q

What is testosterone replacement used for?

A

Used in men who have lost their libido.
Tends to be used as a patch.
Also used for hair loss in men (finasteride)

30
Q

Can finasteride be used in women for hair loss?

A

NO - pregnancy categorised as X

Only other drug which is X is thalidomide