KELNOR

Clinical safety rating: caution

Comprehensive clinical and safety monograph for KELNOR (KELNOR).

How it works

Combined oral contraceptive; inhibits ovulation by suppressing gonadotropin release (FSH and LH) primarily via progestational activity; increases viscosity of cervical mucus to inhibit sperm penetration; alters endometrium.

What the body does with it

Metabolism	Hepatic; ethinyl estradiol is metabolized via CYP3A4; drospirenone is metabolized via CYP3A4.
Excretion	Primarily renal excretion of unchanged drug (70-80%) and glucuronide conjugate (10-15%); biliary/fecal elimination accounts for <5%.
Half-life	Terminal elimination half-life 12-15 hours; clinically relevant for once-daily dosing.
Protein binding	97-99% bound primarily to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	0.6-0.8 L/kg, indicating distribution into total body water.
Bioavailability	Oral: 85-90% due to minimal first-pass metabolism.
Onset of Action	Oral: 30-60 minutes; intravenous: within 5 minutes.
Duration of Action	Oral: 12-24 hours; intravenous: 6-12 hours depending on dose and indication.

Classification & Brands

Dosing & administration

KELNOR (norethindrone acetate and ethinyl estradiol) is a combined oral contraceptive. Typical adult dose: 1 tablet (norethindrone acetate 1 mg/ethinyl estradiol 20 mcg) orally once daily for 21 days, followed by 7 placebo tablets, starting on day 1 of menstrual cycle.

Dosage form	TABLET
Renal impairment	No specific dose adjustment is recommended for renal impairment. However, use with caution in patients with impaired renal function due to potential fluid retention.
Liver impairment	Contraindicated in patients with Child-Pugh Class B or C (moderate to severe hepatic impairment) due to reduced clearance. Use with caution in Child-Pugh Class A (mild impairment); consider alternative contraception.
Pediatric use	Safety and efficacy in pediatric patients have not been established for ages <16 years (premenarchal use not indicated). For postmenarchal females aged ≥16 years, same dosing as adults.
Geriatric use	Not indicated for use in postmenopausal women. No specific studies in elderly; avoid in women >60 years due to increased thrombotic risk.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for KELNOR (KELNOR).

Breastfeeding	Contraindicated during breastfeeding. M/P ratio unknown; drug excreted in breast milk with potential for serious adverse effects in nursing infants.
Teratogenic Risk	FDA Pregnancy Category X. First trimester exposure associated with cardiovascular and neural tube defects. Second and third trimester exposure linked to fetal growth restriction and preterm delivery.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use combination hormonal contraceptives.

Side Effect Profile

Serious Effects

Absolute Contraindications

Current or history of thromboembolic disorders; cerebrovascular or coronary artery disease; valvular heart disease with complications; diabetes with vascular involvement; headaches with focal neurological symptoms; undiagnosed abnormal uterine bleeding; known or suspected pregnancy; liver tumors or active liver disease; renal impairment; adrenal insufficiency; uncontrolled hypertension; age >35 and smoking.

Clinical Precautions

Precautions

Increased risk of thromboembolic disorders; liver disease; hypertension; hyperkalemia; depression; gallstone disease; glucose intolerance; fluid retention; hereditary angioedema; chloasma; monitor blood pressure and glucose.

Clinical Tips & Counseling

Drug interactions

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KELNOR

Clinical safety rating: caution

Comprehensive clinical and safety monograph for KELNOR (KELNOR).

How it works

What the body does with it

Metabolism	Hepatic; ethinyl estradiol is metabolized via CYP3A4; drospirenone is metabolized via CYP3A4.
Excretion	Primarily renal excretion of unchanged drug (70-80%) and glucuronide conjugate (10-15%); biliary/fecal elimination accounts for <5%.
Half-life	Terminal elimination half-life 12-15 hours; clinically relevant for once-daily dosing.
Protein binding	97-99% bound primarily to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	0.6-0.8 L/kg, indicating distribution into total body water.
Bioavailability	Oral: 85-90% due to minimal first-pass metabolism.
Onset of Action	Oral: 30-60 minutes; intravenous: within 5 minutes.
Duration of Action	Oral: 12-24 hours; intravenous: 6-12 hours depending on dose and indication.

Classification & Brands

Dosing & administration

Dosage form	TABLET
Renal impairment	No specific dose adjustment is recommended for renal impairment. However, use with caution in patients with impaired renal function due to potential fluid retention.
Liver impairment	Contraindicated in patients with Child-Pugh Class B or C (moderate to severe hepatic impairment) due to reduced clearance. Use with caution in Child-Pugh Class A (mild impairment); consider alternative contraception.
Pediatric use	Safety and efficacy in pediatric patients have not been established for ages <16 years (premenarchal use not indicated). For postmenarchal females aged ≥16 years, same dosing as adults.
Geriatric use	Not indicated for use in postmenopausal women. No specific studies in elderly; avoid in women >60 years due to increased thrombotic risk.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for KELNOR (KELNOR).

Breastfeeding	Contraindicated during breastfeeding. M/P ratio unknown; drug excreted in breast milk with potential for serious adverse effects in nursing infants.
Teratogenic Risk	FDA Pregnancy Category X. First trimester exposure associated with cardiovascular and neural tube defects. Second and third trimester exposure linked to fetal growth restriction and preterm delivery.
Fetal Monitoring