HEATHER
HEATHER- norethindrone tablet
Glenmark Pharmaceuticals Inc., USA
Rx only
Patients should be counseled that oral contraceptives do not protect against transmission of HIV (AIDS) and other sexually transmitted diseases (STDs) such as Chlamydia, genital herpes, genital warts, gonorrhea, hepatitis B, and syphilis.
DESCRIPTION
Each pale yellow HEATHER tablet provides a continuous oral contraceptive regimen of 0.35 mg norethindrone, USP daily, and the inactive ingredients include corn starch, lactose monohydrate, magnesium stearate, povidone, talc, D&C Yellow No. 10 aluminum lake and FD&C Yellow No. 6 aluminium lake.
The chemical name for norethindrone, USP is 17-Hydroxy-19-Nor-17α-pregn-4-en-20-yn-3-one. The structural formula follows:
Norethindrone, USP
Therapeutic class = oral contraceptive
CLINICAL PHARMACOLOGY
1. Mode of Action
HEATHER progestin-only oral contraceptives prevent conception by suppressing ovulation in approximately half of users, thickening the cervical mucus to inhibit sperm penetration, lowering the mid-cycle LH and FSH peaks, slowing the movement of the ovum through the fallopian tubes, and altering the endometrium.
2. Pharmacokinetics
Absorption:
Norethindrone is rapidly absorbed with maximum plasma concentrations occurring within 1 to 2 hours after HEATHER administration (see Table 1). Norethindrone appears to be completely absorbed following oral administration; however, it is subject to first pass metabolism resulting in an absolute bioavailability of approximately 65%.
Figure 1: Mean ± SD Norethindrone Plasma Concentrations Following HEATHER Administration
Peak plasma concentrations occur approximately 1 hour after administration (mean Tmax 1.2 hours). The mean (SD) Cmax was 4816.8 (1532.6) pg/mL and generally occurred within 1 hour (mean) of tablet administration, ranging from 0.5 to 2 hours. The mean (SD) Cavg was 885 (250) pg/mL, however, the mean concentration at 24 hrs was 130 (47) pg/mL.
Table 1 provides summary statistics of the pharmacokinetic parameters associated with single dose HEATHER administration.
Pharmacokinetic Parameter | Norethindrone 0.35 mg |
Tmax (hr) | 1.2 ± 0.5 |
Cmax (pg/mL) | 4817 ± 1533 |
AUC(0-48) (pg•h/mL) | 21233 ± 6002 |
t1/2 (h) | 7.7 ± 0.5 |
The food effect on the rate and extent of norethindrone absorption after HEATHER administration has not been evaluated.
Distribution:
Following oral administration, norethindrone is 36% bound to sex hormone-binding globulin (SHBG) and 61% bound to albumin. Volume of distribution of norethindrone is approximately 4 L/kg.
Metabolism:
Norethindrone undergoes extensive biotransformation, primarily via reduction, followed by sulfate and glucuronide conjugation; less than 5% of a norethindrone dose is excreted unchanged; greater than 50% and 20-40% of a dose is excreted in urine and feces, respectively. The majority of metabolites in the circulation are sulfate, with glucuronides accounting for most of the urinary metabolites.
Excretion:
Plasma clearance rate for norethindrone has been estimated to be approximately 600 L/day. Norethindrone is excreted in both urine and feces, primarily as metabolites. The mean terminal elimination half-life of norethindrone following single dose administration of HEATHER is approximately 8 hours.
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. The following table lists the pregnancy rates for users of all major methods of contraception.
Emergency Contraceptive Pill: Treatment initiated within 72 hours after unprotected intercourse reduces the risk of pregnancy by at least 75%.* Lactational Amenorrhea Method: LAM is a highly effective, temporary method of contraception.† Source: Trussell J, Contraceptive Efficacy. In: Hatcher RA, Trussell J, Stewart F, Cates W, Stewart GK, Kowal D, Guest F, Contraceptive Technology: Seventeenth Revised Edition. New York, NY: Irvington Publishers, 1998. | |||
| |||
% 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 | ||
IUDs | |||
Progesterone T | 2.0 | 1.5 | 81 |
Copper T 380A | 0.8 | 0.6 | 78 |
LNg 20 | 0.1 | 0.1 | 81 |
Depo-Provera® | 0.3 | 0.3 | 70 |
Levonorgestrel Implants (Norplant®) | 0.05 | 0.05 | 88 |
Female Sterilization | 0.5 | 0.5 | 100 |
Male Sterilization | 0.15 | 0.10 | 100 |
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