How do oral contraceptives work

oral contraceptives, hormone replacement therapy

1. 28. How do oral contraceptives work?

Used to prevent pregnancy. Prevent fertilization by inhibiting ovulation and changing the cervical
mucus and the lining of the uterus to make implantation of an embryo less likely.

Most oral contraceptives contain a combination of estrogen and progestin; a few preparation
contain only progestin. The most common estrogen used for contraception is ethinyl estradiol,
and the most common progestin is norethindrone. Typically, drug administration of an oral
contraceptive begins on day 5 of the ovarian cycle and continues for 21 days. During the other 7
days of the month, the client takes a placebo. While placebo serves no pharmacological purpose,
it does encourage the client to take the pills on a daily basis.

The estrogen-progestin oral contraceptives act by providing negative feedback to the pituitary to
shut down the secretion of LH and FSH. Without the influence of these pituitary hormones, the
ovarian follicle cannot mature and ovulation is prevented. The estrogen-progestin agents also
reduce the likelihood of implantation by making the uterine endometrium less favourable to
receive an embryo. In addition to their contraceptive function, these agents are sometimes
prescribed to promote timely and regular monthly cycles and to reduce the incidence of
dysmenorrhea.

The three types of estrogen-progestin formulation are monophasic, biphasic, and triphasic. The
most common is monophasic, which delivers a constant amount of estrogen and progestin
throughout the menstrual cycle. In biphasic agents, the amount of estrogen in each pill remains
constant, but the amount of progestin is increased toward the end of the menstrual cycle to better
nourish the uterine lining. In triphasic formulations, the amounts of both estrogen and progestin
vary in three distinct phases during the 28-day cycle. The progestin-only oral contraceptives,
sometimes called minipills, prevent pregnancy primarily by producing thick, viscous mucus at the
entrance to the uterus that discourages penetration by sperm. They also tends to inhibit
implantation of a fertilized egg. Minipills are less effective than estrogen-progestin combinations,
having a failure rate of 1% to 4%.


29. What is hormone replacement therapy (HRT) used for?

Used to treat symptoms of menopause, prevent long-term consequences of estrogen loss, and in
some cases, to treat prostate and breast cancer.

Refers to replacement of both estrogen and progesterone, whereas estrogen replacement
therapy (ERT) refers to the replacement of estrogen alone. The term hormone therapy (HT) is a
more general term that is used to refer to either administration of estrogen alone (women who
have had a hysterectomy), or combined estrogen/progestin therapy (women with a uterus).
30. What are the potential side effects of HRT?
Patient receiving HRT experienced a small, though significant, increased risk of serious adverse
effects such as coronary artery disease, stroke, breast cancer, dementia, and venous
thromboembolism.

2. Women can experience side effects during hormone therapy; these can be divided into more minor side
effects, and more serious side effects. The more minor side effects are more common than the serious
side effects, and are generally perceived by women as "annoying." These symptoms include:
 headaches,
 nausea,
 breast pain.
The more serious health concerns for women undergoing hormone therapy (HT) include:
Hormone therapy (HT) increases the risk of vein clots in the legs (deep vein thrombosis ) and
blood clots in the lungs (pulmonary embolus) by about 2 or 3 fold.
Uterine Cancer (endometrial cancer): Research shows that women who have their uterus and use
estrogen alone are at risk for endometrial cancer. Today, however, most doctors prescribe the
combination of estrogen and progestin. Progestin protects against endometrial cancer.
Breast cancer: Recent research indicates that hormone therapy (HT), and especially EPT, increases
the risk of breast cancer, although the increase in risk is very small.
Heart disease: Even though hormone therapy (HT) lowers the bad LDL cholesterol and raises the
good HDL cholesterol, hormone therapy (HT) increases the risk of heart attacks in women who already
have heart disease, as well as in women who do not have known heart disease.
Abnormal vaginal bleeding: Women on hormone therapy (HT) are more likely than
other postmenopausal women to experience abnormal vaginal bleeding.
Stroke: Hormone therapy (HT) slightly increased the risk of stroke in women studied in the Women's
Health Initiative.

Reference: Adams, M., Holland, L., Bostwick, P., King S., Pharmacology for Nurse. A
Pathophysiological Approach. Canadian ed. p. 586, 591
http://www.medicinenet.com/hormone_therapy/page3.htm