Rx Drugs Info

aygestin (norethindrone acetatetablet 

Revised JULY 2007

Rx only


AYGESTIN® (norethindrone acetate tablets, USP) - 5 mg oral tablets.

AYGESTIN®, (17-hydroxy-19-nor-17α-pregn-4-en-20-yn-3-one acetate), a synthetic, orally active progestin, is the acetic acid ester of norethindrone. It is a white, or creamy white, crystalline powder.

Image from Drug Label Content

AYGESTIN® tablets contain the following inactive ingredients: lactose, magnesium stearate, and microcrystalline cellulose.


Norethindrone acetate induces secretory changes in an estrogen-primed endometrium. On a weight basis, it is twice as potent as norethindrone.



Norethindrone acetate is completely and rapidly deacetylated to norethindrone (NET) after oral administration, and the disposition of norethindrone acetate is indistinguishable from that of orally administered norethindrone. Norethindrone acetate is rapidly absorbed from AYGESTIN® tablets, with maximum plasma concentration of norethindrone generally occurring at about 2 hours post-dose. The pharmacokinetic parameters of norethindrone following single oral administration of AYGESTIN® in 29 healthy female volunteers are summarized in Table 1.

Table 1 Pharmacokinetic Parameters after a Single Dose of AYGESTIN® in Healthy Women
AUC = area under the curve,
Cmax = maximum plasma concentration,
tmax = time at maximum plasma concentration,
t1/2 = half-life,
SD = standard deviation
AYGESTIN® (n=29) Arithmetic Mean ± SD
Norethindrone (NET)
AUC (0-inf)(ng/ml*h) 166.90±56.28
Cmax (ng/ml) 26.19 ± 6.19
tmax (h) 1.83 ± 0.58
t1/2 (h) 8.51 ± 2.19
Image from Drug Label Content

Figure 1. Mean Plasma Concentration Profile after a Single Dose of 5 mg Administered to 29 Healthy Female Volunteers under Fasting Conditions

Effect of Food

The effect of food administration on the pharmacokinetics of AYGESTIN® has not been studied.


Norethindrone is 36% bound to sex hormone-binding globulin (SHBG) and 61% bound to albumin. Volume of distribution of norethindrone is about 4 L/kg.


Norethindrone undergoes extensive biotransformation, primarily via reduction, followed by sulfate and glucuronide conjugation. The majority of metabolites in the circulation are sulfates, with glucuronides accounting for most of the urinary metabolites.


Plasma clearance value for norethindrone is approximately 0.4 L/hr/kg. Norethindrone is excreted in both urine and feces, primarily as metabolites. The mean terminal elimination half-life of norethindrone following a single dose administration of AYGESTIN® is approximately 9 hours.

Special Populations


The effect of age on the pharmacokinetics of norethindrone after AYGESTIN® administration has not been evaluated.


The effect of race on the disposition of norethindrone after AYGESTIN® administration has not been evaluated.

Renal Insufficiency

The effect of renal disease on the disposition of norethindrone after AYGESTIN® administration has not been evaluated. In premenopausal women with chronic renal failure undergoing peritoneal dialysis who received multiple doses of an oral contraceptive containing ethinyl estradiol and norethindrone, plasma norethindrone concentration was unchanged compared to concentrations in premenopausal women with normal renal function.

Hepatic Insufficiency

The effect of hepatic disease on the disposition of norethindrone after AYGESTIN® administration has not been evaluated. However, AYGESTIN® is contraindicated in markedly impaired liver function or liver disease.

Drug Interactions

No pharmacokinetic drug interaction studies investigating any drug-drug interactions with AYGESTIN® have been conducted.


AYGESTIN® is indicated for the treatment of secondary amenorrhea, endometriosis, and abnormal uterine bleeding due to hormonal imbalance in the absence of organic pathology, such as submucous fibroids or uterine cancer. AYGESTIN®  is not intended, recommended or approved to be used with concomitant estrogen therapy in postmenopausal women for endometrial protection.



1. Cardiovascular disorders

Patients with risk factors for arterial vascular disease (e.g., hypertension, diabetes mellitus, tobacco use, hypercholesterolemia, and obesity) and/or venous thromboembolism (e.g., personal history or family history of VTE, obesity, and systemic lupus erythematosus) should be managed appropriately.

2. Visual abnormalities

Discontinue medication pending examination if there is a sudden partial or complete loss of vision or if there is sudden onset of proptosis, diplopia, or migraine. If examination reveals papilledema or retinal vascular lesions, medication should be discontinued.



Information for the Patient

Healthcare providers are advised to discuss the PATIENT INFORMATION leaflet with patients for whom they prescribe AYGESTIN®.

Drug/Laboratory Tests Interactions

The following laboratory test results may be altered by the use of estrogen/progestin combination drugs:

  1. Accelerated prothrombin time, partial thromboplastin time, and platelet aggregation time; increased platelet count; increased factors II, VII antigen, VIII antigen, VIII coagulant activity, IX, X, XII, VII-X complex, II-VII-X complex, and beta-thromboglobulin; decreased levels of antifactor Xa and antithrombin III, decreased antithrombin III activity; increased levels of fibrinogen and fibrinogen activity; increased plasminogen antigen and activity.
  2. Increased thyroid-binding globulin (TBG) levels leading to increased circulating total thyroid hormone levels as measured by protein-bound iodine (PBI), T4 levels (by column or by radioimmunoassay) or T3 levels by radioimmunoassay. T3 resin uptake is decreased, reflecting the elevated TBG. Free T4 and free T3 concentrations are unaltered. Patients on thyroid replacement therapy may require higher doses of thyroid hormone.
  3. Other binding proteins may be elevated in serum (i.e., corticosteroid binding globulin (CBG), sex hormone binding globulin (SHBG)) leading to increased circulating corticosteroid and sex steroids, respectively. Free or biologically active hormone concentrations are unchanged. Other plasma proteins may be increased (angiotensinogen/renin substrate, alpha-1-antitrypsin, ceruloplasmin).
  4. Increased plasma HDL and HDL2 cholesterol subfraction concentrations, reduced LDL cholesterol concentration, increased triglycerides levels.
  5. Impaired glucose metabolism.
  6. Reduced response to metyrapone test.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

Some beagle dogs treated with medroxyprogesterone acetate developed mammary nodules. Although nodules occasionally appeared in control animals, they were intermittent in nature, whereas nodules in treated animals were larger and more numerous, and persisted. There is no general agreement as to whether the nodules are benign or malignant. Their significance with respect to humans has not been established.


Category X

Norethindrone acetate is contraindicated during pregnancy as it may cause fetal harm when administered to pregnant women. Several reports suggest an association between intrauterine exposure to progestational drugs in the first trimester of pregnancy and congenital abnormalities in male and female fetuses. Some progestational drugs induce mild virilization of the external genitalia of female fetuses.

Nursing Mothers

Detectable amounts of progestins have been identified in the milk of mothers receiving them. Caution should be exercised when progestins are administered to a nursing woman.

Pediatric Use

AYGESTIN® tablets are not indicated in children.



The following adverse reactions have been observed in women taking progestins:


Therapy with AYGESTIN® must be adapted to the specific indications and therapeutic response of the individual patient.

Secondary amenorrhea, abnormal uterine bleeding due to hormonal imbalance in the absence of organic pathology

2.5 to 10 mg AYGESTIN® may be given daily for 5 to 10 days to produce secretory transformation of an endometrium that has been adequately primed with either endogenous or exogenous estrogen.

Progestin withdrawal bleeding usually occurs within three to seven days after discontinuing AYGESTIN® therapy. Patients with a past history of recurrent episodes of abnormal uterine bleeding may benefit from planned menstrual cycling with AYGESTIN®.


Initial daily dosage of 5 mg AYGESTIN® for two weeks. Dosage should be increased by 2.5 mg per day every two weeks until 15 mg per day of AYGESTIN® is reached. Therapy may be held at this level for six to nine months or until annoying breakthrough bleeding demands temporary termination.


AYGESTIN® (norethindrone acetate tablets, USP) are available as:

5 mg: White, oval, flat-faced, beveled-edge tablet scored on one side. Debossed with 5 AYGESTIN on the unscored side and stylized b / 424 on the scored side.
Available as follows:
Bottle of 50 tablets NDC 51285-424-10
Blister Pack of 10 tablets NDC 51285-424-69

Store at 20º to 25ºC (68º to 77ºF) [See USP Controlled Room Temperature].


Read this PATIENT INFORMATION before you start taking AYGESTIN® tablets and read what you get each time you refill AYGESTIN® tablets. There may be new information. This information does not take the place of talking to your healthcare provider about your medical condition.

What is the most important information I should know about AYGESTIN®(A Progestin Hormone) tablets?

What is AYGESTIN®?

AYGESTIN® is similar to the progesterone hormones naturally produced by the body. Your healthcare provider may provide AYGESTIN® as individual tablets or in a blister pack of 10 tablets.

What are AYGESTIN®  tablets used for?

AYGESTIN® tablets are used for the treatment of secondary amenorrhea (absence of menstrual periods in women who have previously had a menstrual period who are not pregnant), the treatment of endometriosis, and the treatment of irregular menstrual periods due to hormone imbalance.

Who should not take AYGESTIN®  tablets?

You should not take AYGESTIN®tablets if you are postmenopausal, pregnant or breast-feeding.

You should not take AYGESTIN® tablets if you have the following conditions:

What are the risks associated with AYGESTIN®  tablets?

These are some of the warning signs of serious side effects with progestin therapy

Call your healthcare provider right away if you get any of these warning signs, or any other unusual symptom that concerns you.

Common side effects include

Other side effects include

These are not all the possible side effects of progestin and/or estrogen therapy. For more information, ask your healthcare provider or pharmacist.

What can I do to lower my chances of getting a serious side effect with AYGESTIN® ?

General information about the safe and effective use of AYGESTIN®  tablets

Medicines are sometimes prescribed for conditions that are not mentioned in patient information leaflets. Do not take AYGESTIN® tablets for conditions for which it was not prescribed. Do not give AYGESTIN® tablets to other people, even if they have the same symptoms you have. It may harm them.

Keep AYGESTIN®  tablets out of the reach of children.

This leaflet provides a summary of the most important information about progestin and/or estrogen therapy. If you would like more information, talk with your healthcare provider or pharmacist. You can ask for information about AYGESTIN® that is written for health professionals.

What are the ingredients in AYGESTIN®  tablets?

AYGESTIN® tablets contain the following inactive ingredients: lactose, magnesium stearate, and microcrystalline cellulose.

Subsidiary of Barr Pharmaceuticals, Inc.
Pomona, New York 10970

Revised JULY 2007

Aygestin (norethindrone acetate)
Product Code 51285-424 Dosage Form TABLET
Route Of Administration ORAL DEA Schedule
Name (Active Moiety) Type Strength
norethindrone acetate (norethindrone) Active 5 MILLIGRAM  In 1 TABLET
lactose Inactive  
magnesium stearate Inactive  
microcrystalline cellulose Inactive  
Characteristic Appearance Characteristic Appearance
Color WHITE (WHITE) Score 2
Shape OVAL (OVAL) Symbol true
Imprint Code 5;AYGESTIN;b/424 Coating false
Size 11mm
# NDC Package Description Multilevel Packaging
1 51285-424-10 50 TABLET In 1 BOTTLE None
2 51285-424-69 1 BLISTER PACK In 1 CARTON contains a BLISTER PACK
2 10 TABLET In 1 BLISTER PACK This package is contained within the CARTON (51285-424-69)


Data are from FDA and U.S. National Library of Medicine.