Contraception Flashcards
Define Contraception
Prevention of pregnancy before foetal implantation.
What is the aim of conraception?
- Abstinence – 100% reliable!
- Block access of sperm to egg.
- Disrupt female reproductive cycle
Female Reproductive Cycle
Female HPG Axis
Hormonal Contraceptives
- Combined oral contraceptives
- Progesterone-only contraceptives
- ‘Morning after pill’
Name an abortive agent
RU486 (mifepristone)
The Combined Oral Contraceptives consists of which 2 hormones?
Oestrogen & Progesterone
Maintaining sustained levels of Oestrogen & Progesterone mimics which reproductive event?
Pregnancy→HPG Axis
Combined Oral Contraceptives mechaism of action
Inhibit GnRH release
Inhibit FSH & LH secretion
Inhibit follicle maturation Inhibit ovulation Inhibit Corpus luteum
Thicken cervical mucous→Modify tubule motility→Endometrial changes
Combined Oral Contraceptives: Efficacy
- very low failure rate (0.05%)
- usually caused by missed doses, drug interactions
- (some antibiotics), diarrhoea & vomiting.
Combined Oral Contraceptives: Side effects
- increased risk of CVD, breast cancer.
- minor effects include nausea, weight gain, depression
Combined Oral Contraceptives: Health benefits
- decreased risk of ovarian & endometrial cancer.
- decreased incidence of PID & ovarian cysts.
Progesterone Only Contraceptives
- Mini-pill
- Depo contraceptive injection
- Contraceptive implant
(slow release, higher dose)
All contain synthetic progestogens.
Progesterone Only Mini-Pill
- Pituitary still responds to GnRH
- Inhibit FSH & LH secretion
- Can be ovulatory – depends on degree of HPG suppression
- Thicken cervical mucous→Modify tubule motility
→endometrial changes
Depo (medroxyprogesterone acetate) Contraceptive Injections
- Inhibit GnRH release
- Inhibit FSH & LH secretion
- Inhibit follicle maturation→Inhibit ovulation
→Inhibit Corpus luteum
- Thicken cervical mucous→Modify tubule motility
→Endometrial changes
Progesterone Only Contraceptives: Efficacy
- very low failure rate (<1%) if taken correctly.
- (mini-pill must be taken daily in very short time window).
Progesterone Only Contraceptives: Side effects
- rare (acne, breast tenderness and breast enlargement,
- mood changes, headaches, nausea).
- Depo injections – can take up to 2 years to recover normal fertility.
Morning After Pill
- Emergency contraception used within 72 hrs after unprotected sex.
- Progesterone only.
- Primary mechanism of action is to inhibit ovulation.
- Suppression of HPG – inhibit FSH and LH.
- Efficacy rates ~ 75-85%.
RU486 (Mifepristone)
Progesterone ANTAGONIST
Licensed in the UK for termination of pregnancy NOT post-coital contraception.
RU486 (Mifepristone) Mechanism of action depends on stage of cycle:
- Mid-cycle →disrupts ovulation
- Luteal phase →prevents implantation
- After implantation →causes loss of foetus
Male Contraceptive Pill
Several under development with different modes of action:
- stop sperm production
- inhibit sperm motility
- inhibit testosterone production
Example: dimethandrolone undecanoate (DMAU) – androgen receptor agonist
Concerns for Male Contraceptive Pill
Concerns over side-effects including sexual dysfunction & weight gain