Norethindrone

NORETHINDRONE- norethindrone tablet
Glenmark Generics Inc.,USA

Rx only

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.

structure
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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 0.5%. However, the typical failure rate is estimated to be closer to 5%, due to late or omitted pills. Table 1 lists the pregnancy rates for users of all major methods of contraception.

Table 1: Percentage of Women Experiencing an Unintended Pregnancy During the First Year of Typical Use and the First Year of Perfect Use of Contraception and the Percentage Continuing Use at the End of the First Year. United States.
Adapted from Hatcher et al, 1998, Ref. #1
Emergency Contraceptive Pills: Treatment initiated within 72 hours after unprotected intercourse reduces the risk of pregnancy by at least 75%*
Lactational Amenorrhea Method: LAM is highly effective, temporary method of contraception
Source: Trussell J, Contraceptive efficacy. In Hatcher RA, Trussel J, Stewart F, Cates W, Stewart GK, Kowal D, Guest F, Contraceptive Technology: Seventeenth Revised Edition. New York NY: Irvington Publishers, 1998.
*
The treatment schedule is one dose within 72 hours after unprotected intercourse, and a second dose 12 hours after the first dose. The Food and Drug Administration has declared the following brands of oral contraceptives to be safe and effective for emergency contraception: Ovral® (1 dose is 2 white pills), Alesse® (1 dose is 5 pink pills), Nordette® or Levlen® (1 dose is 2 light-orange pills), Lo/Ovral® (1 dose is 4 white pills), Triphasil ® or Tri-Levlen® (1 dose is 4 yellow pills)
However, to maintain effective protection against pregnancy, another method of contraception must be used as soon as menstruation resumes, the frequency or duration of breastfeeds is reduced, bottle feeds are introduced, or the baby reaches six months of age.
Among couples attempting to avoid pregnancy, the percentage who continue to use a method for one year
§
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
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
#
The percents 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 one year. This estimate was lowered slightly (to 85%) to represent the percent who would become pregnant within one year among women now relying on reversible methods of contraception if they abandoned contraception altogether
Þ
Foams, creams, gels, vaginal suppositories, and vaginal film
ß
Cervical mucus (ovulation) method supplemented by calendar in the pre-ovulatory and basal body temperature in the post-ovulatory phases
à
With spermicidal cream or jelly
è
Without spermicides

% 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)

Chance #

85

85

Spermicides Þ

26

6

40

Periodic abstinence

25

63

Calendar

9

Ovulation Method

3

Sympto-Thermal ß

2

Post-Ovulation

1

Cap à

Parous Women

40

26

42

Nulliparous Women

20

9

56

Sponge

Parous Women

40

20

42

Nulliparous Women

20

9

56

Diaphragm à

20

6

56

Withdrawal

19

4

Condom è

Female (Reality®)

21

5

56

Male

14

3

61

Pill

5

71

Progestin Only

0.5

Combined

0.1

IUD

Progesterone T

2.0

1.5

81

Copper T380A

0.8

0.6

78

LNg 20

0.1

0.1

81

Depo-Provera®

0.3

0.3

70

Norplant® and Norplant-2®

0.05

0.05

88

Female Sterilization

0.5

0.5

100

Male Sterilization

0.15

0.10

100

Norethindrone tablets have not been studied for and are not indicated for use in emergency contraception.

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