Norethindrone
NORETHINDRONE- norethindrone tablet
Glenmark Pharmaceuticals Inc., USA
Patients should be counseled that this product does not protect against HIV infection (AIDS) and other sexually transmitted diseases.
DESCRIPTION
Each tablet contains 0.35 mg norethindrone, USP. Inactive ingredients include colloidal silicon dioxide, corn starch, D&C Yellow No. 10, ethyl cellulose, lactose anhydrous, magnesium stearate, microcrystalline cellulose, povidone, sodium starch glycolate, methylene chloride, isopropyl alcohol and talc.
CLINICAL PHARMACOLOGY
1. Mode of Action
Norethindrone progestin-only oral contraceptives prevent conception by suppressing ovulation in approximately half of users, thickening the cervical mucus to inhibit sperm penetration, lowering the midcycle LH and FSH peaks, slowing the movement of the ovum through the fallopian tubes and altering the endometrium.
2. Pharmacokinetics
Serum progestin levels peak about two hours after oral administration, followed by rapid distribution and elimination. By 24 hours after drug ingestion, serum levels are near baseline, making efficacy dependent upon rigid adherence to the dosing schedule. There are large variations in serum levels among individual users. Progestin-only administration results in lower steady-state serum progestin levels and a shorter elimination half-life than concomitant administration with estrogens.
INDICATIONS AND USAGE
1. Indications
Progestin-only oral contraceptives are indicated for the prevention of pregnancy.
2. Efficacy
If used perfectly, the first-year failure rate for progestin-only oral contraceptives is 0.3%. However, the typical failure rate is estimated to be closer to 9%, due to late or omitted pills. Table 1 lists the pregnancy rates for users of all major methods of contraception.
Emergency Contraception: Emergency contraceptive pills or insertion of a copper intrauterine contraceptive after unprotected intercourse substantially reduces the risk of pregnancy.9 (See Chapter 6.). | |||
Lactational Amenorrhea Method: LAM is highly effective, temporary method of contraception 10 (See Chapter 18.). | |||
Source: Trussell J. Contraceptive Efficacy. In Hatcher RA, Trussell J, Nelson AL, Cates W, Kowal D, Policar M. Contraceptive Techology: Twentieth Revised Edition. New York NY: Ardent Media, 2011. | |||
% of Women Experiencing an Unintended Pregnancy within the First Year of Use | % of Women Continuing Use at One Year | ||
Method (1) | Typical Use (2) | Perfect Use (3) | (4) |
No method4 | 85 | 85 | |
Spermicides | 28 | 18 | 42 |
Fertility awareness-based methods | 24 | 47 | |
Standard Days method6 | 5 | ||
TwoDay method6 | 4 | ||
Ovulation method6 | 3 | ||
Symptothermal method6 | 0.4 | ||
Withdrawal | 22 | 4 | 46 |
Sponge | 36 | ||
Parous women | 24 | 20 | |
Nulliparous women | 12 | 9 | |
Condom7 | |||
Female (fc) | 21 | 5 | 41 |
Male | 18 | 2 | 43 |
Diaphragm8 | 12 | 6 | 57 |
Combined pill and progestin-only pill | 9 | 0.3 | 67 |
Norelgestromin and ethinyl estradiol patch | 9 | 0.3 | 67 |
NuvaRing | 9 | 0.3 | 67 |
Depo-Provera | 6 | 0.2 | 56 |
Intrauterine contraceptives | |||
ParaGard (copper T) | 0.8 | 0.6 | 78 |
Mirena (LNg) | 0.2 | 0.2 | 80 |
Implanon | 0.05 | 0.05 | 84 |
Female sterilization | 0.5 | 0.5 | 100 |
Male sterilization | 0.15 | 0.10 | 100 |
Notes:
- 1.
- Among typical couples who initiate use of a method (not necessarily for the first time), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason. Estimates of the probability of pregnancy during the first year of typical use for spermicides, withdrawal, fertility awareness-based methods, the diaphragm, the male condom, the oral contraceptive pill, and Depo-Provera are taken from the 1995 National Survey of Family Growth corrected for underreporting of abortion; see the text for the derivation of estimates for the other methods.
- 2.
- Among couples who initiate use of a method (not necessarily for the first time) and who use it perfectly (both consistently and correctly), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason. See the text for the derivation of the estimate for each method.
- 3.
- Among couples attempting to avoid pregnancy, the percentage who continue to use a method for 1 year.
- 4.
- The percentages becoming pregnant in columns (2) and (3) are based on data from populations where contraception is not used and from women who cease using contraception in order to become pregnant. Among such populations, about 89% become pregnant within 1 year. This estimate was lowered slightly (to 85%) to represent the percentage who would become pregnant within 1 year among women now relying on reversible methods of contraception if they abandoned contraception altogether.
- 5.
- Foams, creams, gels, vaginal suppositories, and vaginal film.
- 6.
- The Ovulation and TwoDay methods are based on evaluation of cervical mucus. The Standard Days method avoids intercourse on cycle days 8 through 19. The Symptothermal method is a double-check method based on evaluation of cervical mucus to determine the first fertile day and evaluation of cervical mucus and temperature to determine the last fertile day.
- 7.
- Without spermicides.
- 8.
- With spermicidal cream or jelly.
- 9.
- ella, Plan B One-Step and Next Choice are the only dedicated products specifically marketed for
- emergency contraception. The label for Plan B One-Step (one dose is 1 white pill) says to take the pill within 72 hours after unprotected intercourse. Research has shown that all of the brands listed here are effective when used within 120 hours after unprotected sex. The label for Next Choice (one dose is 1 peach pill) says to take 1 pill within 72 hours after unprotected intercourse and another pill 12 hours later. Research has shown that both pills can be taken at the same time with no decrease in efficacy or increase in side effects and that they are effective when used within 120 hours after unprotected sex. The FDA has in addition declared the following 19 brands of oral contraceptives to be safe and effective for emergency contraception: Ogestrel (1 dose is 2 white pills), Nordette (1 dose is 4 light-orange pills), Cryselle, Levora, Low-Ogestrel, Lo/Ovral, or Quasence (1 dose is 4 white pills), Jolessa, Portia, Seasonale or Trivora (1 dose is 4 pink pills), Seasonique (1 dose is 4 light-blue-green pills), Enpresse (one dose is 4 orange pills), Lessina (1 dose is 5 pink pills), Aviane or LoSeasonique (one dose is 5 orange pills), Lutera or Sronyx (one dose is 5 white pills), and Lybrel (one dose is 6 yellow pills).
Norethindrone tablets have not been studied for and are not indicated for use in emergency contraception.
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