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Professional Information — Kelnor 1/35 28 Day

Full FDA prescribing details for healthcare professionals.

Last updated · May 16, 2026Source: DailyMed ↗
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Highlights of Prescribing InformationRevised: Feb 04, 2023

Patients should be counseled that this product does not protect against HIV infection (AIDS) and other sexually transmitted diseases.

Indications and Usage

Kelnor 1/35 (28 Day Regimen) (ethynodiol diacetate and ethinyl estradiol tablets) is indicated for the prevention of pregnancy in women who elect to use oral contraceptives as a method of contraception.

Oral contraceptives are highly effective. Table 1 lists the typical accidental pregnancy rates for users of combination oral contraceptives and other methods of contraception. The efficacy of these contraceptive methods, except sterilization and progestogen implants and injections, depends upon the reliability with which they are used. Correct and consistent use of methods can result in lower failure rates.

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.

% of Women Experiencing an

Unintended Pregnancy

Within the First Year of Use

% of Women Continuing Use

at One Year 1

Method

(1)

Typical Use 2

(2)

Perfect Use 3

(3)

(4)

Chance 4

85

85

Spermicides 5

26

6

40

Periodic abstinence

25

63

Calendar

9

Ovulation method

3

Sympto-thermal 6

2

Post-ovulation

1

Withdrawal

19

4

Cap 7

Parous women

40

26

42

Nulliparous women

20

9

56

Sponge

Parous women

40

20

42

Nulliparous women

20

9

56

Diaphragm 7

20

6

56

Condom 8

Female (Reality®)

21

5

56

Male

14

3

61

Pill

5

71

Progestin only

0.5

Combined

0.1

IUD

Progesterone T

2

1.5

81

Copper T 380A

0.8

0.6

78

LNg 20

0.1

0.1

81

Injection (Depo-Provera®)

0.3

0.3

70

Implant (Norplant® and Norplant-2®)

0.05

0.05

88

Female sterilization

0.5

0.5

100

Male sterilization

0.15

0.1

100

Emergency Contraceptive Pills: Treatment initiated within 72 hours after unprotected intercourse reduces the risk of pregnancy by at least 75%. 9

Lactational Amenorrhea Method: LAM is a highly effective, temporary method of contraception. 10

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, in press.1

1. Among couples attempting to avoid pregnancy, the percentage who continue to use a method for one year.

2. 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.

3. 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.

4. 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.

5. Foams, creams, gels, vaginal suppositories, and vaginal film.

6. Cervical mucus (ovulation) method supplemented by calendar in the pre-ovulatory and basal body temperature in the post-ovulatory phases.

7. With spermicidal cream or jelly.

8. Without spermicides.

9. 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).

10.  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.

Dosage and Administration

To achieve maximum contraceptive effectiveness, oral contraceptives must be taken exactly as directed and at intervals of 24 hours.

IMPORTANT: If the Sunday start schedule is selected, the patient should be instructed to use an additional method of protection until after the first week of administration in the initial cycle. The possibility of ovulation and conception prior to initiation of use should be considered.

Kelnor 1/35 (28 Day Regimen) (ethynodiol diacetate and ethinyl estradiol tablets)

Dosage Schedule

The Kelnor 1/35 (28 Day Regimen) tablet dispenser contains 21 light yellow active tablets arranged in three numbered rows of 7 tablets each, followed by a fourth row of 7 white placebo tablets.

Days of the week are printed above the tablets, starting with Sunday on the left.

28 Day Schedule

For a DAY 1 START, count the first day of menstrual flow as Day 1 and the first tablet (light yellow) is then taken on Day 1. For a SUNDAY START when menstrual flow begins on or before Sunday, the first tablet (light yellow) is taken on that day. With either a DAY 1 START or SUNDAY START, 1 tablet (light yellow) is taken each day at the same time for 21 days. Then the white tablets are taken for 7 days, whether bleeding has stopped or not. After all 28 tablets have been taken, whether bleeding has stopped or not, the same dosage schedule is repeated beginning on the following day.

Special Notes

Spotting, Breakthrough Bleeding, or Nausea

If spotting (bleeding insufficient to require a pad), breakthrough bleeding (heavier bleeding similar to a menstrual flow), or nausea occurs the patient should continue taking her tablets as directed. The incidence of spotting, breakthrough bleeding or nausea is minimal, most frequently occurring in the first cycle. Ordinarily spotting or breakthrough bleeding will stop within a week. Usually the patient will begin to cycle regularly within two to three courses of tablet-taking. In the event of spotting or breakthrough bleeding organic causes should be borne in mind. (See WARNINGS, No. 12 .)

Missed Menstrual Periods

 Withdrawal flow will normally occur 2 or 3 days after the last active tablet is taken. Failure of withdrawal bleeding ordinarily does not mean that the patient is pregnant, providing the dosage schedule has been correctly followed. (See WARNINGS, No. 7 .)

If the patient has not adhered to the prescribed dosage regimen, the possibility of pregnancy should be considered after the first missed period, and oral contraceptives should be withheld until pregnancy has been ruled out.

If the patient has adhered to the prescribed regimen and misses two consecutive periods, pregnancy should be ruled out before continuing the contraceptive regimen.

The first intermenstrual interval after discontinuing the tablets is usually prolonged; consequently, a patient for whom a 28 day cycle is usual might not begin to menstruate for 35 days or longer. Ovulation in such prolonged cycles will occur correspondingly later in the cycle. Posttreatment cycles after the first one, however, are usually typical for the individual woman prior to taking tablets. (See WARNINGS, No. 12 .)

Missed Tablets

 If a woman misses taking one active tablet, the missed tablet should be taken as soon as it is remembered. In addition, the next tablet should be taken at the usual time. If two consecutive active tablets are missed in week 1 or week 2 of the dispenser, the dosage should be doubled for the next 2 days. The regular schedule should then be resumed, but an additional method of protection must be used as backup for the next 7 days if she has sex during that time or she may become pregnant.

If two consecutive active tablets are missed in week 3 of the dispenser or three consecutive active tablets are missed during any of the first 3 weeks of the dispenser, direct the patient to do one of the following: Day 1 Starters should discard the rest of the dispenser and begin a new dispenser that same day; Sunday Starters should continue to take 1 tablet daily until Sunday, discard the rest of the dispenser and begin a new dispenser that same day. The patient may not have a period this month; however, if she has missed two consecutive periods, pregnancy should be ruled out. An additional method of protection must be used as a backup for the next 7 days after the tablets are missed if she has sex during that time or she may become pregnant.

While there is little likelihood of ovulation if only one active tablet is missed, the possibility of spotting or breakthrough bleeding is increased and should be expected if two or more successive active tablets are missed. However, the possibility of ovulation increases with each successive day that scheduled active tablets are missed.

If one or more placebo tablets of Kelnor are missed, the Kelnor schedule should be resumed on the eighth day after the last light yellow tablet was taken. Omission of placebo tablets in the 28 tablet courses does not increase the possibility of conception provided that this schedule is followed.

Contraindications

Kelnor 1/35 is contraindicated in females who are known to have or develop the following conditions:

  • Thrombophlebitis or thromboembolic disorders
  • A past history of deep vein thrombophlebitis or thromboembolic disorders
  • Cerebral vascular disease, myocardial infarction, or coronary artery disease, or a past history of these conditions
  • Current diagnosis of, or history of, breast cancer, which may be hormone-sensitive
  • Known or suspected carcinoma of the female reproductive organs or suspected estrogen-dependent neoplasia, or a history of these conditions
  • Undiagnosed abnormal genital bleeding
  • History of cholestatic jaundice of pregnancy or jaundice with prior oral contraceptive use
  • Past or present, benign or malignant liver tumors
  • Known or suspected pregnancy
  • Are receiving Hepatitis C drug combinations containing ombitasvir/paritaprevir/ritonavir, with or without dasabuvir, due to the potential for ALT elevations (see WARNINGS, Risk of Liver Enzyme Elevations with Concomitant Hepatitis C Treatment).

Adverse Reactions

Post Marketing Experience

Five studies that compared breast cancer risk between ever-users (current or past use) of COCs and never-users of COCs reported no association between ever use of COCs and breast cancer risk, with effect estimates ranging from 0.90 - 1.12 (Figure 2).

Three studies compared breast cancer risk between current or recent COC users (<6 months since last use) and never users of COCs (Figure 2). One of these studies reported no association between breast cancer risk and COC use. The other two studies found an increased relative risk of 1.19 - 1.33 with current or recent use. Both of these studies found an increased risk of breast cancer with current use of longer duration, with relative risks ranging from 1.03 with less than one year of COC use to approximately 1.4 with more than 8-10 years of COC use.

Figure 2: Risk of Breast Cancer with Combined Oral Contraceptive Use

Figure from prescribing information

RR = relative risk; OR = odds ratio; HR = hazard ratio. “ever COC” are females with current or past COC use; “never COC use” are females that never used COCs.

An increased risk of the following serious adverse reactions has been associated with the use of oral contraceptives (see WARNINGS ):

  • Thrombophlebitis and thrombosis
  • Arterial thromboembolism
  • Pulmonary embolism
  • Myocardial infarction and coronary thrombosis
  • Cerebral hemorrhage
  • Cerebral thrombosis
  • Hypertension
  • Gallbladder disease
  • Benign and malignant liver tumors, and other hepatic lesions

There is evidence of an association between the following conditions and the use of oral contraceptives, although additional confirmatory studies are needed:

  • Mesenteric thrombosis
  • Neuro-ocular lesions (e.g., retinal thrombosis and optic neuritis)

The following adverse reactions have been reported in patients receiving oral contraceptives and are believed to be drug-related:

  • Nausea
  • Vomiting
  • Gastrointestinal symptoms (such as abdominal cramps and bloating)
  • Breakthrough bleeding
  • Spotting
  • Change in menstrual flow
  • Amenorrhea during or after use
  • Temporary infertility after discontinuation of use
  • Edema
  • Chloasma or melasma, which may persist
  • Breast changes: tenderness, enlargement, secretion
  • Change in weight (increase or decrease)
  • Change in cervical erosion or secretion
  • Diminution in lactation when given immediately postpartum
  • Cholestatic jaundice
  • Migraine
  • Rash (allergic)
  • Mental depression
  • Reduced tolerance to carbohydrates
  • Vaginal candidiasis
  • Change in corneal curvature (steepening)
  • Intolerance to contact lenses

The following adverse reactions or conditions have been reported in users of oral contraceptives and the association has been neither confirmed nor refuted:

  • Premenstrual syndrome
  • Cataracts
  • Changes in appetite
  • Cystitis-like syndrome
  • Headache
  • Nervousness
  • Dizziness
  • Hirsutism
  • Loss of scalp hair
  • Erythema multiforme
  • Erythema nodosum
  • Hemorrhagic eruption
  • Vaginitis
  • Porphyria
  • Impaired renal function
  • Hemolytic uremic syndrome
  • Acne
  • Changes in libido
  • Colitis
  • Budd-Chiari syndrome
  • Endocervical hyperplasia or ectropion
1

Drug Interactions

Reduced efficacy and increased incidence of breakthrough bleeding and menstrual irregularities have been associated with concomitant use of rifampin. A similar association, though less marked, has been suggested for barbiturates, phenylbutazone, phenytoin sodium, and possibly with griseofulvin, ampicillin, and tetracyclines. Administration of troglitazone concomitantly with a combination oral contraceptive (estrogen and progestin) reduced the plasma concentrations of both hormones by approximately 30%. This could result in loss of contraceptive efficacy.

Concomitant Use with HCV Combination Therapy – Liver Enzyme Elevation

Do not co-administer Kelnor with HCV drug combinations containing ombitasvir/paritaprevir/ritonavir, with or without dasabuvir, due to potential for ALT elevations (see WARNINGS, Risk of Liver Enzyme Elevations with Concomitant Hepatitis C Treatment).

Overdosage

Serious ill effects have not been reported following acute ingestion of large doses of oral contraceptives by young children.180, 181 Overdosage may cause nausea, and withdrawal bleeding may occur in females.

Description

Kelnor® 1/35 (28 Day Regimen) (ethynodiol diacetate and ethinyl estradiol tablets USP): Each light yellow tablet contains 1 mg of ethynodiol diacetate, USP and 35 mcg of ethinyl estradiol, USP. The inactive ingredients include anhydrous lactose, D&C yellow no. 10 aluminum lake, magnesium stearate, microcrystalline cellulose, polacrilin potassium, and povidone. Each white tablet is a placebo containing only inert ingredients as follows: anhydrous lactose, hypromellose, magnesium stearate, and microcrystalline cellulose.

The chemical name for ethynodiol diacetate, USP is 19-nor-17α-pregn-4-en-20-yne-3β, 17-diol diacetate, and for ethinyl estradiol, USP it is 19-nor-17α-pregna-1, 3, 5 (10)-trien-20-yne-3, 17-diol. The structural formulas are as follows:

Ethynodiol Diacetate, USP

Figure from prescribing information

C24H32O4 M.W. 384.51

Ethinyl Estradiol, USP

Figure from prescribing information

C20H24O2 M.W. 296.40

Ethynodiol Diacetate structural formula Ethinyl Estradiol structural formula

Clinical Pharmacology

Combination oral contraceptives act primarily by suppression of gonadotropins. Although the primary mechanism of this action is inhibition of ovulation, other alterations in the genital tract, including changes in the cervical mucus (which increase the difficulty of sperm entry into the uterus) and the endometrium (which may reduce the likelihood of implantation) may also contribute to contraceptive effectiveness.

How Supplied / Storage and Handling

Kelnor® 1/35 (28 Day Regimen) (ethynodiol diacetate and ethinyl estradiol tablets USP) is packaged in cartons of six blister card dispensers. Each blister card dispenser contains 21 light yellow, round, flat-faced, beveled-edge, unscored tablets, debossed with stylized b on one side and 14 on the other side and 7 white, round, flat-faced, beveled-edge, unscored placebo tablets, debossed with stylized b on one side and 143 on the other side. Each light yellow tablet contains 1 mg of ethynodiol diacetate, USP and 0.035 mg of ethinyl estradiol, USP. Each white tablet contains inert ingredients.

 

Available in cartons of six blisters

 

NDC 0555-9064-58

Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].

KEEP THIS AND ALL MEDICATIONS OUT OF THE REACH OF CHILDREN.

Patient Counseling Information

See patient labeling printed below.

Sources

RxCUI: 753483

NDC: [{'@sourceNdc9': '00555-9064', 'ndc9': ['54868-5942']}]

Last fetched: May 16, 2026

Source: DailyMed ↗

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