What are the two main classes of HC?
Combined hormonal contraception (CHC)
Progestogen only contraceptives (POP)
What is the MOA of CHC’s?
To prevent ovulation
- The oestrogen & progestogen components of the CHCs act on the hypothalamo-pituitary ovarian axis to suppress Lh and FSH production therefore ovulation does not occur
When cervical mucus is increased what happens?
Acts as a mechanical barrier for sperm
What are the functions of oestrogen and progestogen?
Oestrogen causes the endometrium to proliferate and grow
Progestogen prevents hyperplasia (excessive growth) of the endometrium
Why does a withdrawal bleed occur?
7-day pill-free interval causes oestrogen and progestogen concentrations to fall
What do COC’s contain?
Oestrogen & progestogen
What are the differences in COC preparations?
Monophasic (first line) - oestrogen & progestogen amount constant throughout the cycle
Phasic - amounts vary over the 21 day cycle
(Biphasic - two different sets of active tabs, Triphasic - three, Quadraphasic - four)
When are phasic COCs used?
Women who do not have a withdrawal bleed/women who have breakthrough bleeding with monophasic
What is the general dose of ethinylestradiol given?
30-35mcg
What are the two types of preparations of COC pills?
Standard - 21 active tablets, no tablet taken for 7 days (HFI)
ED preparations - 21 active, 7 placebo to allow withdrawal bleed
What are the preparations of COC to be aware of?
Qlaira - quadriphasic used for heavy menstrual bleeding, 28 days taken continuously
Dianette- not used solely for contraception, increased risk of VTE
What are the rules for monophasic COC initiation?
Day 1 up to & including day 5 of cycle - no additional contraception needed, start on day 1
Day 6 and onwards - additional precautions needed for 7 days (9 days for qlaira)
Postpartum - up to and including day 21 postpartum no additional contraception needed
Termination/miscarriage - started immediately/up to day 5 no contraception needed
What can the HFI interval be shortened to?
4 days
What to consider if COC has been missed?
- When the pill was missed
- How many pills the patient has missed
- Where they are in the cycle (pack)
- Which pill is being taken
What action should be taken if COC pill missed?
- If one active pill missed (>48-72hrs)
Missed pill should be taken as soon as remembered
Remaining pills continued at same time - If two or more (max 7) pills missed >72 hours late
Take as soon as remember, continue pills as normal, condoms for 7 days
Consider EC if UPSI is during HFI or week 1 - If over 9 days
Consider EC, missed pill taken, avoid sex/barrier until 7 pills taken as normal
What are the advantages and disadvantages of COC?
- Prevent pregnancy
- Menstrual bleeding lighter
- Reduced risk of cancer (ovary, uterus, colon)
- Reduced acne
Disadvantages
- Headaches, nausea, breast tenderness, mood changes
- BP may increase
- No protection against STIs
What drugs interact with COCs?
Enzyme-inducing drugs (rifampicin, rifabutin, carbamazepine, phenobarbital, phenytoin, St John’s Wort, lamotrigine) reduce the effectiveness of COC
- Advise other contraceptive method or use barrier method whilst taking and for 4 weeks after
- Breakthrough bleeding can occur as low serum oestrogen concentrations
Note lamotrigine dose may need to be increased
What if vomiting/diarrhoea occurs within 3 hours of taking pill?
Take another pill ASAP
What are the risks of COC?
- MI/stroke
- Increased risk of VTE
- Breast cancer/cervical cancer
- Age (>35 years, avoid >50 years)
Reasons to stop COC?
- Sudden severe chest pain
- Sudden breathlessness
- Severe pain in calf/one leg
- Severe stomach pain
- Neuro effects
- Hepatitis/jaundice/liver enlargement
What is the combined contraceptive patch?
Evra (1 patch applied once weekly for 3 weeks, then 7 day free interval)
If patch detached < 48hrs re-apply, no add precaution
If patch detached > 48hrs start new cycle (now week 1 and the new day for patch changes), use barrier for 7 days
What is the MOA of POP pill?
Alter the cervical mucus making it more viscous and impenetrable to sperm
What is the MOA of desogestrel?
Inhibition of ovulation
What are the different POP pills?
- Traditional: no break, 3 hour window for missed pills e.g. Noriday, Micronor, Norgeston
- Desogestrel: no break, 12 hour window for missed pills, usually first line
