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Contraception – Combined Oral Contraceptive Pill – COCP

Oral contraceptive pill

Oral contraceptive pill

Introduction

Combined oral contraceptive pills contain both oestrogen and progestogen. This method is:
The COCP pill is frequently prescribed, but, from the prescribers perspective is also one of the more complex methods of contraception due to the long list of contraindications and cautions.
COCP preparations can be divided into three main types:

Monophasic – each pill contains the same amount of progesterone and oestrogen.
Phasic – the concentrations of hormones in each pill varies with the time of the cycle.

Every Day pills – 28 days supply, with 7 days of placebo pills in days 22-28. The pills must be taken in the right order.

They are available in varying strengths. The lowest dose that produces the desired effects should be used. Typically the oestrogen component is a variant of oestrogen known as ethinylestradiaol – and typically doses are 20 – 40 micrograms. COCPs may contain a variety of progestogens such as norethisterone, levonorgestrel or desogestrel.

Prescribing the COCP is not a simple process of “just writing the prescription” although patients may feel frustrated at repeated thorough risk fact-checking at the time of prescription. In my career I have upset many women by refusing to prescribe the pill when contraindicated – even when they have been previously taking it for a long time. I have also seen the death of a teenage girl from massive PE shortly after starting on the pill, and several other cases of PE and huge DVT. This is rare but it certainly comes to mind whenever I write a prescription! – Dr Tom Leach

Summary

COMBINED PILL
EFFECTIVENESS
>99% when taken correctly.
PREPERATIONS
e.g. Microgynon (Ethinylestradiol and levonorgestrel)
HOW IT WORKS
Contains both oestrogen and progesterone.
Stops ovulation
Thickens cervical mucus preventing passage of perm, thins lining of uterus preventing implantation.
ADVANTAGES
Very effective when taken correctly
reduces bleeding, pain and PMT.
Reduced hirtuism and acne
Reduces risk endometrial and ovarian ca. Possibly [controversial] inc risk breast ca.
Fertility quick to return when ceased, but can take up to 3 months
DISADVANTAGES
Progestrogens cause :Headache, Breast tenderness, breakthrough bleeding
Oestrogens cause: Nausea and vomiting, Fluid retention, Mood changes
Inc risk of cardiovascular disease (thromboembolism)
CI
Absolute CI’s – see UKMEC for a full list
Migraine – with typical focal aura, or severe migraine >72hrs,
Personal history venous or arterial thrombosis,
Heart disease
Previous DVT or PE, Stroke
FHx in first degree relative of VTE
Liver disease
Age >50, or age >35 and smoker
Smoker >40/day any age
Increased BMI – avoid if BMI >35, caution if 30-35
Avoid if two or more of following:
Fx venous thromboembolism / arterial disease, obesity, long-term immobilization, varicose veins.
DM, hypertension, smoking, >35yrs, obesity, migraine
NB: epilepsy (particularly carbamazepine) drugs and ST. john’s Wort interfere with COCP metabolism so patients on these drugs may need higher doses.
COMMENTS
Take 21 pills and one week off (some preparations have placebo 7 days, in a 28 day packet)
Start first course on 1st day period. If starting after day 4 of period, or if miss pill >24hr time allocation must use barrier contraception for 7 days.

Efficacy

Mechanism

Side effects

Oestrogen increases the risk of cardiovascular disease (notably thromboembolus). It also causes:

Progestogens can cause: headache, depression, acne, breakthrough bleeding and breast symptoms. Many of these resolve themselves after several weeks/months of treatment, and can be solved if a different progestrogen is used, however, some progestogens are also associated with increased thromboembolic risk

Missed doses

The general rule is that the combined pill can be taken within 24 hours of the usual time of administration, and still be effective.
If a pill is missed, the woman should take it as soon as she remembers, and then continue taking the rest of the pills at their normal time; even if this means taking two at once
A ‘missed pill’ is one that is >24 hours after she should have taken it

The greatest risk of pregnancy if a pill is missed is at the beginning and end of a cycle.
If 2 pills are missed (i.e. >24 after time should have been taken) then there is a risk of pregnancy – especially if the pill was missed in the first 7 days of the cycle.

Vomiting and diarrhoea

Drug interactions

Several drugs are known to reduce the effectiveness of the pill (’enzyme inducing drugs’). You should always check other medications the patient is on (in the BNF) before prescribing a contraceptive, and seek expert advice. Some common examples of interactions are given below:
In women taking these drugs it is advisable to seek alternative methods of contraception

When taking a course of antibiotics

Surgery

It is advisable to discontinue all oestrogen-containing contraceptive 4 weeks before major surgery to reduce the thromboembolus risk. You can safely resume them at the first menses > 2 weeks after surgery.

Contraindications / reasons to stop taking immediately

Cautions

If two or more of the following are present, alternative contraception should be recommended

Prescribing

Women with RF’s for cardiovascular disease should be prescribed the lowest does of oestrogen (20micrograms ethinylestradiol), or should be prescribed an alternative if >2 RF’s are present
Women >50 should not use the COC as better alternatives are available, and the cardiovascular disease risk is high
Inform patient to seek help immediately if:

Missing the withdrawal bleed

Length of prescription

Commencing treatment

No Previous contraception

Changing from progesterone only pill

After child birth

After miscarriage / abortion

Examples

Alternative preparations

Skin patch

 

Vaginal contraceptive ring

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