1. Oral contraceptive types.
a. Monophasic: Contain a constant dose of estrogen and progesterone in each of the 21 contraceptively active pills (e.g., Orthonova 1/35, ovcon 35, and yasmin).
b. Biphasic: Contain a constant dose of estrogen progestin over 21 days. The last 7 days contain estrogen only in a lower dose (e.g., mircette).
c. Triphasic: Contain a varying dose of progestin. In some types the estrogen dose in the 21 contraceptively active pills is varied. The purpose of this manipulation is to keep the patient on the lowest dose possible throughout the cycle, while preventing pregnancy at the same rate (e.g., Estrostep, trilevelen, and orthotricyclen).
d. Progestin-only pill: Contains even lower doses of progestin in 28 contraceptively active pills (e.g., Micronor and ovrette).
e. Ring therapy: A nonbiodegradeable vaginal ring that contains a progestin etonogestrel and ethinyl estradiol The patient receives an average of 0.015 mg/day of the estrogen and 0.120 mg/day of progestin. The ring is inserted into the vagina for 3 weeks and is removed for 1 week to provoke a menstrual cycle. Indications and contraindications are the same as oral contraceptives (e.g., Nuvaring).
f. The contraceptive patch: It is a transdermal trilayer patch. The inner layer carries the active compounds norelgestromin, progestin, and 20 |ig of ethinyl estradiol. Currently the patch is being reevaluated concerning steady-state blood levels. It is applied weekly to the abdomen, buttocks, upper back, and upper outer arm. The patch is changed weekly for 3 weeks and rotated each time to a different site. Indications and contraindications are equal to other hormonal combined contraceptives (e.g., Orthoevra).
2. The most commonly used estrogen is ethinyl estradiol in a dose containing less than 35 \ig of estrogen.
3. Mestranol is the estrogen used in the higher-dosed pills. Pills with estrogen levels greater than 50 ng are no longer available.
4. Most commonly used progestins are norethindrone, levonorgestrel, norgestrel, norethindrone acetate, or ethynodiol diacetate.
5. Less androgenic progestins are norgestimate and destogestrel. Gestodene is another new progestin along with norelgestromin, dros-peridone, and etongetrel.
6. Mechanism of action: Suppression of pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion, which suppresses ovulation. The progestin portion of the pill causes changes in cervical mucus and endometrium, which afford birth control because ovulation may occur on oral contraceptives.
7. Effectiveness rate: If taken correctly, only 1 in 1000 women is expected to get pregnant within the first year on combined oral contraceptives. The typical failure rate of combined oral contraceptives is about 3%. Progestin-only pills have about the same effectiveness rate as the combined pills.
8. Administration of combination oral contraceptives.
a. A daily ritual should be associated with oral contraceptive use. Many women are more likely to remember to take the pills at night before bedtime. This may prevent nausea because the patient will be sleeping. A woman should begin taking oral contraceptives either on the Sunday following the first day of her period or on the first day of her period.
b. It should be stressed that taking the pills daily at the same time is necessary for optimum effectiveness.
c. If one or two pills are missed, have the patient double up on the pills until she catches up.
d. If two or more pills are missed, backup birth control should be used and the pack should be completed.
9. Antibiotic use and the Pill: The only antibiotic proven to decrease the effectiveness rate of the Pill is rifampin. The dermatologic literature has produced a guideline to follow regarding contraceptive pill and antibiotic mixing (Box 1).
BOX 1. Categories of Antibiotics
Category A: Antibiotic That Likely Reduces Birth Control Pill Effectiveness
Category B: Antibiotics Associated with Oral Contraceptive Failure in Three or More Case Reports
Ampicillin Amoxicillin Metronidazole Tetracycline
Category C: Antibiotics Associated with Oral Contraceptive Failure in at Least One Case Report