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Case 2 > Drugs Used as Contraceptives > Flashcards

Drugs Used as Contraceptives Flashcards

1
Q

What is a hormone

A

A biochemical modulator of cell function

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2
Q

What do hormones regulate

A

Homeostatic functions

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3
Q

What is a paracrine effect

A

A short range effect (small blast radius)

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4
Q

What is an autocrine effect

A

Acts on itself (feedsback on itself)

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5
Q

What is an endocrine effect

A

Transport in the blood stream to a distant organ (distally acting)

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6
Q

What do hypothalamic paracrine hormones influence secretion on

A

Endocrine hormones from the anterior pituitary gland

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7
Q

What do endocrine anterior pituitary gland influence hormone secretion on

A

Hormone secretion in the ovaries

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8
Q

Describe the classic homeostatic negative feedback

A

Hypothalamus stimulates anterior pituitary gland which stimulates the ovaries which inhibits hypothalamus and anterior pituitary gland

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9
Q

What do sex hormones all start with

A

Cholesterol

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10
Q

Describe production of progesterones and oestrogens

A

A cascade of enzyme activity from pre-cursor cholesterol in the ovaries and placenta: cholesterol -> pregnenolone -> progesterone -> androstenedione -> oestrogens

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11
Q

What converts cholesterol to pregnenolone

A

Mitochondrial CYP450scc

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12
Q

What converts pregnenolone to progesterone

A

Dehydrogenase

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13
Q

What converts progesterone to androstenedione

A

Hydrolyase and lyase

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14
Q

What converts androstenedione to oestrogen

A

Aromatase

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15
Q

What are the different types of oestrogen

A

Oestradiol, oestriol, oestrone

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16
Q

Where does the generation of cholestrol and oestrogen occur

A

In the ovaries and the placenta

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17
Q

When do steroids only have an effect

A

When they bind to receptors

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18
Q

What are steroids agonists for

A

Mobile nuclear receptors

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19
Q

What does the steroid receptor complex often require

A

A chaperone protein to mediate association

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20
Q

What does the steroid-receptor complex act as

A

A transcriptional regulator of nuclear DNA

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21
Q

What are steroid receptors

A

Mobile cytoplasmic receptors that eitehr up or down regulate a gene which means that steroids have diverse and potent effects

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22
Q

How long is the menstrual cycle

A

28 days

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23
Q

What is the menstrual cycle controlled by

A

GnRH, FSH, LH, oestrogen and progesterone

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24
Q

Where is FSH secreted from

A

Anterior pituitary

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25
Q

What does FSH cause

A

A Graafian follicle to develop and be viable

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26
Q

When do FHH levels peak

A

Around the point of follicle rupture (ovulation)

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27
Q

Where is oestrogen secreted from

A

As the follicle develops it secreted oestrogen in increasing amounts

28
Q

What does oestrogen cause

A

Thickening of the endometrium

29
Q

Describe the feedback mechanisms of oestrogen

A

Negatively feeds back on the pituitary during follicular phase. The peak of oestrogen transiently sensitises LH-secreting cells to effects of GnRH causing a mid-cycle surge of LH

30
Q

What elicits follicle rupture

A

The surge of LH causes by oestrogen

31
Q

Where is LH secreted from

A

Anterior pituitary

32
Q

What does LH cause

A

A Graafian follicle to develop and mature

33
Q

When does ovulation occur

A

At day 14- LH surge causes the follicle to rupture resulting in ovulation

34
Q

What does the ruptured follicle turn into

A

Corpus luteum

35
Q

Where is progesterone secreted from

A

The corpus luteum

36
Q

Describe the feedback activity of progesterone

A

Progesterone negatively feeds back on the pituitary decreasing LH

37
Q

What effect does progesterone have on the endometriumin regard to implantation

A

Makes it viable for fertilised egg implantation

38
Q

What effect does progesterone have on endometriumin regard to sperm

A

Makes endometrium inhospitable to sperm

39
Q

What causes the development of one Graafian follicle

A

FSH and LH

40
Q

What happens to the egg after ovulation

A

If fertilised it implants into the endometrium. If not fertilised menstruation occurs

41
Q

What happens to the endometrium in anticipation of implantation

A

It thickens and becomes more vascularised by oestrogen

42
Q

How is the normal menstrual cycle suppressed

A

By giving regular synthetic or structural analogues of oestrogen and progesterone the normal menstrual cycle is suppressed because of the effects on reproductive tissue and the negative feedback on the hypothalamus and the pituitary

43
Q

What does of drug suppresses the normal menstrual cycle

A

A chronic dose

44
Q

What are the routes of administering contraception

A

Oral, implant, coil

45
Q

Describe oestrogen mechanisms and effects

A

Oestrogen and receptor complexes -> transcriptional regulation of genes causing: seconday sexual characteristics, endometrial & uterine growth, vaginal lubrication, ovulation, up-regulation of progesterone receptors, reduces bone loss, increases bone density, increases clotting factors & platelet adhesivity, suppression of gonadotroph cell secretions in the pituitary

46
Q

Describe progesterone mechanisms and effects

A

Progesterone + receptor complexes -> transcriptional regulation of genes causing: promotion of hospitable endometrial domain for implantation, alters viscosity & pH of cervical mucus to make inhospitable to sperm, suppresses maternal immune system during pregnancy, decreases uterine contractility, inhibits lactation, suppression of gonadotroph cell secretions in the pituitary and GnRH from hypothalamus

47
Q

Describe how the combined oral contraceptive pill works

A

The combination of oestrogen (e.g. ethinylestradiol) and progesterone (e.g. levonorgestrel) is a highly effective contraception. Oestrogen suppresses FSH secretion stopping follicle development. Progesterone inhibits LH secretion stopping ovulation and preventing sperm traffic. Both hormones chronically make the endometrium inhospitable to implantation

48
Q

Describe how progesterone-only preparations (POP) work

A

Typically contains noresthisterone or levonorgestrel. progesterones prevent sperm traffic by increasing cervical mucus viscosity and altering pH (more acidic). Chronic use of progesterone inhibits egg implantation in the endometrium. Trick the body into thinking its pregnant

49
Q

Where may progesterone-only preparations be used

A

Where oestrogen is contraindicated

50
Q

When should emergency contraception be used

A

As soon as possible post-coitally if not already taking contraception

51
Q

Describe how emergency contraception works

A

A large dose of progesterone (ulipristal or levonorgestrel) is effective in causing contraception in about 60%-99% of cases

52
Q

What are such large doses as in emergency contraception likely to cause

A

Nausea, vomitting, heachaches and irregular bleeding

53
Q

Describe the adverse side effects of drugs used to prevent pregnancy

A

Combined pill contains lots of oestrogen therefore there is an increased risk of thrombo-embolism. ADRs from serious to inconvenient: thrombo-embolism, stroke, myocardial infarction, increased risk of breast cancer, exposure to STId (if unprotected intercourse), hypertension, skin pigmentation changes, weight gain, nausea, irregular bleeding, mood changes

54
Q

What are contraindications for the pill

A

Pregnant, pre-existing cardiovascular disease, obese, hypercholestererolaemic, smoker over 40, ‘oestrogen sensitive’ breat/ bowel cancer, liver cirrhosis. If patienst is morbidly obese must ensure they are not pregnant, if they are obese= excessive cholsterol

55
Q

Describe labour induction using prostaglandins

A

Uterine muscle contractile sensitivity to prostaglandins increases through pregnancy. PGE-analogues (dinoprost and misoprostol) may be used to induce the coordinated uterine muscle contractions.

56
Q

How can PGE-analogues be given

A

PGE-analogues are prostaglandin-analogues that are given as gels or intravaginally

57
Q

How can unprotected sex trigger labour

A

When couples have unprotected sex the ejaculate from the male contains lots of prostaglandins which can trigger labour

58
Q

Describe labour induction using oxytocin

A

Oxytocin is usually secreted by theh posterior pituitary in response to cervical dilation and suckling. It causes uterine contractions (to expel the placenta). A slow IV infusion of oxytocin induces regular waves of myometrial contraction

59
Q

What happens if the baby suckles straight away after birth

A

Oxytocin is releases which causes waves of myometrial contraction which helps expel the afterbirth

60
Q

Why is oxytocin given as a slow IV infusion

A

A big dose would result in uterine spasm

61
Q

Name an abortifactant used

A

Mifepristone

62
Q

What is mifepristone

A

A progesterone receptor antagonist (means progesterone can’t bind to the receptor) that causes endometrial degeneration and sensitises uterine contraction to prostaglandins

63
Q

What is gemeprost

A

A methyl ester analogue of a PGE1 and is used with mifepristone. It also helps reduce obstetric bleeding causing vasoconstriction

64
Q

What do the social and ethical issues associated with the use of these types of drugs mean

A

You need to think carefully about how you educate your patient about their use in an unbiassed way and whether your own views may interfere with the best management of your patient (this can’t happen)

65
Q

What best describes the composition of the combined oral contraceptive pill

A

It typically contains ethinylestradiol and levonorgestrel

66
Q

Why is there a (small) increased risk of thrombo-embolic events if using contraceptives containing oestrogens

A

Oestrogens increase the levels of some blood-clotting factors and increase the aggregatory potential of platelets

Case 2 (8 decks)

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