[Combined] oral contraceptive pill (OCP's, aka birth control pills) are drugs taken by mouth for birth control.
MOA
Prevent ovulation by suppressing the release of gonadotropins (FSH, LH), thus inhibiting follicular development and preventing ovulation
Progestogen negative feedback, decreases the pulse frequency of GnRH release by the hypothalamus, which decreases secretion of FSH and LH by the anterior pituitary. Decreased FSH inhibits follicular development, preventing an increase in estradiol levels. Progestogen negative feedback and the lack of estrogen positive feedback on LH secretion, prevents a mid-cycle LH surge. Inhibition of follicular development and the absence of a LH surge prevent ovulation
Estrogen was originally included in OCP's for better cycle control, as it stabilizes the endometrium, thereby reducing the incidence of breakthrough bleeding. However, it was found that it also inhibits follicular development, and helps prevent ovulation. Estrogen negative feedback on the anterior pituitary, decreases the secretion of FSH, which inhibits follicular development, and helps prevent ovulation
Progestogen also inhibits sperm penetration through the cervix into the upper genital tract (uterus and fallopian tubes), by decreasing the water content, and increasing the viscosity of the cervical mucus
Classification
Male oral contraceptives are currently not available commercially.
Female oral contraceptives include:
Taken once per day:
Combined oral contraceptive pill, containing estrogen and progestin, including:
1st generation, which are COCP's, containing >=50µg ethinyl estradiol
2nd generation, which are COCP's containng <50µg ethinyl estradiol. Examples include with norethisterone (Norimin), with levonorgestrel (Microgynon, Alesse), with norethisterone (Tri-Cyclen)
3rd generation, which are COCP's containing desogestrel, gestodene, or norgestimate
4th generation, which are COCP's containing drospirenone (Yaz, Yasmin), dienogest, or nomegestrol acetate
Progestin-only pill, which use progestogen alone with doses taken continuously and no gaps between packs. Patients may experience irregular light bleeds, and whilst irregular in the 1st few months of taking, usually setles ot a regular pattern in time. The various types include:
Norethisterone (Micronor)
Etynodiol diacetate
Levonorgestrel
Desogestrel
Lynestrenol
Emergency contraception pills (morning after pills), taken at the time of intercourse, or within a few days afterwards, including:
Yuzpe regimen, using combined oral contraceptives
Ulipristal acetate, an antiprogestogen
Purpose
Inhibit female fertility, if started within 5 days of the beginning of the menstrual cycle. If started any other time in the menstrual cycle, they provide contraception only after 7 consecutive days using the active pills → backup method of contraception is required
Pills are just as effective whether taken continuous for prolonged periods of time, or if just initiated
Non-contraceptive use, including:
PCOS
Endometriosis
Amenorrhea
Menstrual cramps
Adenomyosis
Menorrhagia (excessive menstruation)
Menstruation-related anemia
PID
Dysmenorrhea (painful menstruation)
Premenstrual syndrome
Irregular menstruation, to induce menstruation on a regular cycle, although it actually suppresses normal menstrual cycle, and then mimics a regular 28-day monthly cycle
Female athlete triad, causing menstrual dysfunction, to create menstrual bleeding cycles. However, the underlying cause is energy deficiency, and should be Tx by correcting the imbalance between calories eaten and burned by exercise
Mild to moderate acne
Contraindications
Pre-existing CVD
Familial tendency to form blood clots (e.g. familial factor V Leiden)
Severe obesity
Hypercholesterolemia
Smokers >35yo
Liver tumors
Hepatic adenoma
Severe cirrhosis of the liver
Migraine w/ aura
Known or suspected breast cancer
Method
COCP should be taken orally at the same time each day. If forgotten for more than 12 hours, protection will be reduced
For the 28-pill packs, one is taken each day for the 28 day cycle, where the last week of pills is placebo/sugar pills. They may contain iron supplement, as iron requirements increase during menstruation
For the 21-pill packs, one is taken each day for 3 weeks, following by 1 week of no pills
If pills have been missed:
If 1 is missed [or started a new pack 1 day late], take the last pill missed now, even if this means taking 2 pills in one day. Then, carry on taking the rest of the pack as normal. No extra contraception is required
If 2+ pills are missed [or started a new pack 2+ days late], take the last pill missed now, even if this means taking 2 pills in one day. Leave any earlier missed pills. Carry on taking the rest of the pack as normal. Use extra contraception (e.g. condoms) for the next 7 days
If there has been unprotected sex in the previous 7 days and 2+ pills are missing in the first week of a pack, emergency contraception may be necessary, including either:
Morning after pill (aka emergency contraceptive pill), including ulipristal acetate which has to be taken within 3 days of sex, or levonorgestrel which has to be taken within 5 days of sex, both of which prevent or delay ovulation
IUD, which can be inserted into the uterus up to 5 days after unprotected sex, or up to 5 days after the earliest time the Pt could have ovulated. It may stop an egg from being fertilized or implanting in the Pt's womb
Whilst on the COCP, withdrawal bleed will occur during the placebo week, but will still protect from pregnancy during this week
Risk factors
Mistakes of the user, including:
Forgetting to take the pill one day (especially an active pill)
Not going to the pharmacy on time to renew the prescription
Decreased intestinal absorption of the active pill due to vomiting or diarrhea
Drug interactions of the active pill, by:
Decreasing contraceptive estrogen or progestogen levels, including:
Rifampicin
Barbiturates
Phenytoin
Carbamazepine
Impair bacterial flora, including:
Ampicillin
Doxycycline
Mistake of those providing instructions, including information regarding:
Frequency of intake
Conscious non-compliance with instructions
Side effects
Unintended pregnancy, the probability of pregnancy during the 1st year of "typical" use is 9%, contrasted with 0.3% for "perfect" use
Spotting, especially during the first few months of use → breakthrough bleeding
Irregular periods, especially during the first few months of use
Reductions in menstrual flow, and even amenorrhea
Leukorrhea (increased vaginal secretions)
Mastalgia (breast tenderness)
Increased blinking (32% more)
In older, high-dose COCP's (not seen in current low-dise formulations):
Nausea, vomiting
Increased BP
Melasma (facial skin discoloration)
Headache
Bloating
Swelling of the ankles/feet, weight gain → fluid retention
Positive side effects, include improving conditions
Complications
It does NOT protect against STD's → use condoms
Increased risk of:
CVD risk, including:
HTN
Ischemic stroke
DVT
PE
Breast cancer, which dissapears 7 years after use has stopped
Cervical cancer, in those affected w/ HPV
Liver cancer
Gallstones → excess estrogen increases cholesterol in bile, decreases gallbaldder movement
There is insufficiently strong evidence it causes:
Weight gain
Depression (especially relating to progestin-only contraceptives)
Decreased risk of:
Ovarian cancer
Endometrial cancer
Colorectal cancer
Anemia
Epidemiology
Used by more than 100 million women worldwide
Use varies depending on country, age, education, and marital status
50% of new time users to end the pill before the end of the 1st year, due to breakthrough bleeding or amenorrhea
See also
Birth control (information regarding prescribing to minors)
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