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What is the MOA of oral contraceptives?

1. prevent ovulation - suppress LH and FSH release by preventing estrogen fluctuations by providing pt with stable estrogen level

2. impair implantation - by maintaining elevated progesterone level by providing pt with stable elevated progestin


What are the components of combined oral contraceptives?

An estrogen and a progestin

Estrogen is either ethinyl estradiol or mestranol. [mestranol is a prodrug that is convereted to ethinyl estradiol]

Progestins include: Norethindrone, Norgestrel, Levonorgestrel, Desogestrel, Norgestimate, Drospirenone [most of these progestines have some androgenic activity]


Compare progestins and levels of androgen activity?

Highest androgen activity = levonorgestrel and noregestrel

Lower androgen activity = norethindrone

Even lower activity = desogestrel and noregestimate

Antiandrogenic = Drospirenone


What are monophasic, biphasic and triphasic combined oral contraceptives?

Monophasic = fixed doses of estrogen and progestin

Biphasic and Triphasic = varying proportions of one or both homrones during the pill cycle -- these were introduced to reduce the amt of total monthly dose of progestins and mimic the hormonal changes and menstrual cycle more closely


What are the most common types of combined oral contraceptives?

"low dose" - which contain 35 micrograms of ethinyl estradiol or less

These are more likely to result in contraceptive failure if doses are missed.


What are extended cycle formulations of combined oral contraceptives?

84 days of hormone-containing pills followed by 7 days of a placebo phase -- normal pills have 21 hormonally active pills with 7 placebo pills

**extended cycle has 4 menstrual cycles a year


What is a continuous combination regimen of combined oral contraceptives?

Homrone containing pills for 21 days then very low dose estrogen and progestin for an addition 4-7 days


What is the MOA of combined oral contraceptives?

Prevent fertilization and conception by preventing ovulation. There is a suppression of LH and FSH the prevent ovulation.

Progestin thickens cervical mucus preventing sperm penetration and induces changes in endometrium to impair implantation of the egg


What are the benefits of combined oral contraceptives?

• Reduction on the risk of endometrial cancer
• Reduction in the risk of ovarian cancer
• Improved regulation of menstruation
• Relief of benign breast disease
•Prevention of ovarian cysts
• Reduction in the risk of symptomatic pelvic inflammatorydisease
• Improvement in acne control


AE associated with oral contraceptives?

Nausea, bloating, breakthrough bleeding that improve spontaneously by 3rd cycle.

Breakthrough bleeding is more of a problem with lower doses of estrogen b/c estrogen stabilizes the endometrium.

Insulin resistance b/t progestins may cause insulin resistance by competing with insulin for its receptor. It is very rare that oral contraceptive swill lead to hyperglycemia.

Hirsuitism - due to androgenic progestins

Melasma - due to estrogen stimulation of melanocyte production


Dyslipidemia - low-dose have no impact on HDL, LDL, TAG or total cholesterol levels

CV disorders - increased risk of thromboembolism, thrombiphlembitis, HTN, MI, cerebral and coronary thrombosis esp in women with other risk factors - this is due to estrogen causing increased production of factor VII, factor X , and fibrinogen

Carcinogenic - possible increase in risk of cancer (NOT for endometrial and ovarian though! - oral contraceptives decrease the incidence of these cancers)

Depression - requires cessation of therapy


What drug interactions need to be watched when taking oral contraceptives?

Rifampin - induces hepatic P45- enzymes and increases metabolism of estrogen

[Carbamazepine, oxcarbazepine, phenytoin,
phenobarbital, primidone, topiramate, vigabatrin and St John’s Wort are P450 inducers that may lead to increased metabolism of oral contraceptives]

Antibacterials - that reduce intestinal bacteria decreasing hydroxlyation of estradiol decreasing active estrogen levels


What are the progestin-only pills?

These are not widely used, but contain NORETHINDRONE or NOREGESTREL. They are slightly less effective compared to the combined pills. There is no risk of thromboembolic evens due to lack of estrogen which is really what stimulates the increased risk of thrombosis.

MOA - effectiveness lies within thickening cervical mucus and altering endometrial surface to impair sperm implantation


Contraceptive patch?

Ethinyl estradiol and progestin


Contraceptive ring?

ethinyl estradiol and a progestin


Progestin injection?

**only progestin-only injection contraceptives that is given via IM every 3 months. It is extremely effective and contains depot MEDROXYPROGESTERONE ACETATE (DMPA).
There is a risk of getting irreversible bone mineral density loss as well as weight gain and menstrual irregularities.
*prevents ovulation through negative feedback


Progestin implants?

Contains progestin - it is placed under skin of the upper arm using a preloaded inserter. It is effective for 3 years and the main adverse effect is irregular menstrual bleeding.


Intrauterine systems (IUS)?

• LEVONORGESTREL-releasing intrauterine system
• It has a polyethylene body with a levonorgestrel reservoir
• Effective for 5 years


Hormonal methods of emergency postcoital contraceptives?

Plan B and Next Choice
- both of these contain two tablets of LEVONORGESTREL -- 1st pill is taken within 72 hr and 2nd within 12 hrs
AE - nausea and vomiting

Plan B One-Step
-one tablet of levonorgestrel taken within 72 hours after unprotected intercourse

-contains ulipristal acetate that is a selective progesterone receptor modulator that acts as a progesterone antagonist to inhibit or delay ovulation
-single tablet taken within 5 days of intercourse
AE - levonorgestrel
**only available by prescription


Non-hormonal method of emergency postcoital contraception?

Copper IUD - inserted within 5 days of intercourse