Contraception Flashcards
2 classes of hormonal contraception
Combined hormonal contraception
Progestogen only contraception
How do CHCs work?
oestrogen and progesterone act on the hypothalmo-pituitary ovarian axis to suppress LH and FSH prodution
this inhibits ovulation (no surge in LH and FSH)
What does a surge in LH and FSH cause?
Ovulation
What changes do CHCs do to the cervical mucus?
Increase cervical mucus which acts as a mechanical barrier to sperm
What do CHCs do to the endometrium?
Cause thinning of the endometrium which reduces the chances of implantation
How does the endometrium become thin?
Oestrogen causes the endometrium to proliferate and grow which is opposed by progestogen which prevents hyperplasia (excessive growth) of the endometrium
The endometrium becomes thin, fragile and prone to bleeding
What does the 7 day pill free interval do?
Causes oestrogen and progestogen concentrations to fall
Causes the endometrium to shed, mimicking menstruation
Known as a withdrawal bleed
What do combined oral contraceptives contain?
Oestrogen and progesterone
What is in the oestrogen component?
Synthetic oestrogen - ethinlyestradiol
Some contain mestranol
What does the progestogen component contain?
levonorgestrel
norethisterone
desogestrel
gestodene
drospirenone
First generation of progestogen?
norethisterone
2nd generation of progestogen
levonorgestrel (LNG)
3rd generation of progestogen
desogestrel
gestodene
norgestimate
How do COC preparations differ?
In how the doses vary over the menstrual cycle
2 types of COC preparations
Monophasic COCs
Phasic COCs
Monophasic COCs
First line
Amount of oestrogen/progestogen in each tablet is constant throughout the cycle
Most commonly prescribed
Phasic COCs and 3 types
Amount of oestrogen/progestogen varies over the 21 days
Biphasic: contain 2 different sets of active tablet
Triphasic: contain 3 different sets of active tablet
Quadraphasic: contain 4 different sets of active tablet
Example of biphasic and triphasic COCs
Biphasic- Binovum
Triphasic - Trinordiol
When are phasic COCs used?
In women who don’t have withdrawal bleeding or who have breakthrough bleeding with monophasic preparations
Example of a low strength COC
20mcg ethinylestradiol
Adv/disadv of low strength ethinylestradiol
- useful if risk factors for circulatory disease
- can cause disrupted bleeding patterns
Standard strength COC
- 30-35 mcg ethinylestradiol in monophasic COCs
* 30–40 mcg ethinylestradiol in phased preparations
Equivalent dose of Mestranol to 35mcg ethinylestradiol
50 mcg
2 COC preparations (standard and ED)
- standard preparation - calendar strip of 21 active tabs, 1 taken daily for 21 days and then no tablet taken for 7 days (HFI)
- ED preparations - useful when compliance is a concern, taken continuously, no HFI, 21 active tablets and 7 inert/placebo tabs taken days 22-28 to allow withdrawal bleed
What is Qlaira?
- Quadriphasic pill used in treatment of heavy menstrual bleeding
- Start on day 1 of the cycle
- 28 tabs taken continuously
- Missed pill rules differ
What is Dianette?
- Co-cyprindiol- Cyproterone acetate and ethinylestradiol 2000/35
- not indicated for just a contraceptive
- Used in women who require oral contraception and suffer from acne or hirsutism (hair growth)
- Carries an Increased risk of venous thromboembolism (VTE)
Initiation of monophasic COC days 1-5
- day 1-5: no additional contraception is needed.
* Ideally start on day 1 of the cycle
Initiation of monophasic COC day 6+
Day 6 of menstrual cycle onwards:
Additional precautions are required for 7 days after starting
(9 days for Qlaira)
Initiation of monophasic COC postpartum
Postpartum:
up to and including day 21 postpartum – no additional contraception required
(if not breast feeding and no VTE risk)
Initiation of monophasic COC and miscarriage/termination
If started immediately after or up to day 5, no additional contraception required
What is the standard regimen for COCs?
21 days (21 active pills) and 7 days pill free period
or
28 days (21 active pills and 7 inactive pills) and no pill free period
Tailored use - shortened hormone free interval
21 days (21 active pills) and 4 pill free days
Tailored use - extended use (tri cycling)
Taken for 9 weeks (3 x 21 active pills)
4 or 7 days of pill free interval
Tailored use - flexible or extended use
Continuous use (> 21 days) of active pill until breakthrough bleeding occurs for 3-4 days
4 days of hormone free period
Tailored use - continuous use
Continuous use of active pills
No hormone free interval
Is there a benefit for hormone free interval?
No
Benefits of not taking the hormone free interval
- avoids monthly bleeds
- reduced withdrawal symptoms such as headache and mood changes
- reduced the risk of escape ovulation and pregnancy
What can happen when no pill free period is taken?
Unscheduled bleeding is common
Are tailored regimes licenced?
No
Risk of failure if COC used perfectly
Low <1%
Risk of failure if COC used typically
9% failure
Questions for missed pill
- when the contraception was missed (time since last pill taken)?
- how many pills were missed?
- where are they in the cycle?
- which pill is the patient taking?
What to do if one pill has been missed or < 48hrs since last pill? (COC)
- take the late/missed pill
- continue taking the remaining pills at usual times (even if more than one in a day)
- no additional contraception needed
If 2+ pills missed and > 48hrs since last pill (COC)
- take the most recent pill asap (other missed pills discarded)
- continue taking the remaining pills at usual time (even is more than 1 in day)
- use additional contraception (condoms) or avoid sexual intercourse until pills have been taken for 7 consecutive days
What to do if pills were missed in the last week of pills (days 15-21)?
Omit the hormone free period and finish the pills in the current pack and start a new pack the next day
What to do if it has been 9+ days since last pill taken?
- consider EC if UPSI
- missed pill taken asap
- abstain/barrier method until 7 consecutive pills have been taken
Advantages of COCs
- more effective than barrier methods
- menstrual bleeding is usually regular, lighter and less painful
- reduced severity of acne in some women
- reduced incidence of pre-menstrual tension (PMT)
- reduces risk of ovarian, endometrial and colorectal cancer
- normal fertility returns immediately after stopping the COC
Disadvantages of COCs
- temporarily ADR - headache, nausea, breast tenderness, mood changes (don’t stop in few months, change type of COC)
- BP may increase
- no protection against STDs (use condom)
- less effective than long active reversible methods of contraception
COC interaction with enzyme inducing antibiotics
Enzyme inducers reduce the effectiveness of COCs which can lead to contraception failure
Examples of enzyme inducing antibiotics
Rifampicin
Rifabutin
Short term treatment (< 2 mths) with enzyme inducing antibiotics and COCs
• change to an alternative method of contraception
OR
• continue and use barrier while taking and for 28 days after
What does breakthrough bleeding mean during short term enzyme inducing antibiotics and COC?
A complication that indicates low serum level oestrogen concentrations
What to do when taking COC and long term (> 2 mths) enzyme inducing antibiotic?
Change to an alternative method of contraception
What are non-enzyme inducing antibiotics?
Most broad spectrum antibiotics
Precautions for non-enzyme inducing antibiotics and COCs
- no precautions required
* additional precautions if vomiting or diarrhoea occur
Examples of other enzyme inducing drugs
Anti-epileptics:
- Carbamazepines
- Phenobarbital
- Phenytoin
- Topiramate
COCs and lamotrigine
COC can increase clearance of lamotrigine leading to poor seizure control
Is lamotrigine an enzyme inducer?
No
Other enzyme inducing drugs COCs can interact with
Antiepileptics
Herbal - St. John’s Wort (OTC)
Short term treatment of enzyme inducing drugs and COCs (antiepileptics, lamotrigine, herbal)
Change contraception method or use COC with extended regimen and use barrier/abstain
Abstain/barrier while using and for 28 days after
Long term treatment of other enzyme inducing drugs and COCs
Additional contraception method required
What to do if vomiting within 3hrs of taking COC?
Take another one asap