Logo

OpiCalc

FavoritesSpecialtiesDrugsGuidelinesMost Used

Quick Access

Favorites
Most Used

All Specialties

OpiCalc Logo
Clinical CalculatorsDrugsGuidelines
SpecsDrugsGuides
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
‌
OpiCalc Logo

OpiCalc

Easy, fast, and private medical tools for clinicians. Always free.

No Login Required
Ready for the Bedside

Resources

About UsEditorial PolicyMedical DisclaimerPrivacy PolicyTerms of UseCookie Policy

Support

Contact Us

Clinical Notice:OpiCalc is not a substitute for professional clinical judgment. Always verify dosages and guidelines.

OpiCalc © 2018-2026

•

All Rights Reserved

Registry Hub
Oral Contraceptive (Combined)/Over-the-counter

OPILL

OPILL

Clinical safety rating

caution

Comprehensive clinical and safety monograph for OPILL (OPILL).


Mechanism of Action

Combination oral contraceptive: progestin (norgestimate) suppresses gonadotropin release, inhibiting ovulation; estrogen (ethinyl estradiol) stabilizes endometrial lining and thickens cervical mucus, impeding sperm penetration.

What the body does with it

MetabolismEthinyl estradiol primarily metabolized by CYP3A4; norgestimate rapidly deacetylated to norgestrel and further metabolized by CYP3A4 and CYP2C9.
ExcretionRenal: ~50% (as unchanged drug and metabolites). Biliary/fecal: ~50% (as metabolites).
Half-lifeTerminal half-life: 30-34 hours. Redistribution half-life: 2-4 hours. Clinical context: Steady state achieved in 5-7 days; dosing interval appropriate for once-daily administration.
Protein binding~99% bound to albumin and alpha-1-acid glycoprotein.
Volume of Distribution4-6 L/kg; indicates extensive tissue distribution.
BioavailabilityOral: 60-70% (due to first-pass metabolism).
Onset of ActionOral: 30-60 minutes for therapeutic effect; peak plasma concentrations at 1-2 hours.
Duration of ActionApproximately 24 hours; clinical effect wanes over 12-24 hours post-dose. Once-daily dosing maintains sustained effect.
Molecular WeightEthinyl estradiol: 296.4 Da; Norgestimate: 369.5 Da

Classification & Brands

Dosing & administration

1 tablet (norgestimate 0.180 mg/ethinyl estradiol 0.025 mg) orally once daily for 21 days, followed by 7 days of placebo.

Dosage formTABLET
Renal impairmentNo dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (CrCl <30 mL/min); use with caution.
Liver impairmentContraindicated in acute hepatic disease or severe cirrhosis (Child-Pugh class C). For Child-Pugh class A or B, use only if benefits outweigh risks, with close monitoring.
Pediatric useNot indicated for use before menarche. For postmenarchal adolescents, same dosing as adults: 1 tablet daily for 21 days, then 7 days placebo.
Geriatric useNot indicated for use in postmenopausal women. No studies in geriatric population; contraindicated in women >35 years who smoke cigarettes due to increased cardiovascular risk.

Use during pregnancy

1st trimesterNorgestimate/ethinyl estradiol combination oral contraceptive. Category X. Contraindicated in pregnancy. First trimester use associated with congenital defects (cardiac, limb reduction) in some studies, but data limited. Not indicated for use.
2nd trimesterCategory X. Contraindicated. No therapeutic indication in pregnancy. Accidental exposure unlikely to cause major malformations; fetal exposure if continued may cause androgenic effects?
3rd trimesterCategory X. Contraindicated. Late pregnancy use associated with fetal adrenal suppression and feminization of male fetuses? Avoid.

Clinical note

Comprehensive clinical and safety monograph for OPILL (OPILL).

Placental transferPlacental transfer occurs; ethinyl estradiol crosses at ~2-5% of maternal serum level; norgestimate metabolites also cross. Transfer sufficient to exert hormonal effects on fetus.
BreastfeedingSmall amounts of ethinyl estradiol and norgestimate metabolites excreted in breast milk. May reduce milk production and quality. Not recommended in breastfeeding women, especially during the first 6 months postpartum. Alternative progestin-only methods preferred.
Lactation RatingL3 (Moderately Safe)
Teratogenic RiskFDA Pregnancy Category X. First trimester: Use is contraindicated due to risk of fetal harm, including cardiovascular defects and limb reduction defects. Second and third trimesters: Avoid use; potential for fetal androgenization of female fetuses and other adverse effects.
Fetal MonitoringMonitor fetal development via ultrasound if inadvertent exposure occurs. Assess for signs of androgenization in female fetuses. No routine monitoring recommended as contraindicated in pregnancy.
Fertility EffectsReversible inhibition of ovulation; normal fertility returns upon discontinuation. No long-term fertility impairment.

Warnings & precautions

■ FDA Black Box Warning

Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age and with smoking (especially >35 years). Women who use combination oral contraceptives should be strongly advised not to smoke.

Side Effect Profile

Serious Effects

Absolute Contraindications

Known or suspected pregnancyCurrent venous thromboembolism (VTE) or history of VTEMajor surgery with prolonged immobilizationCurrent or past arterial thromboembolic disease (e.g., MI, stroke)Active liver disease or hepatic impairmentBreast cancer (current or history)Estrogen-sensitive tumorsUndiagnosed abnormal uterine bleedingAge ≥35 and smoking ≥15 cigarettes per dayMigraine with aura if age ≥35Uncontrolled hypertension (≥160/100 mmHg)Diabetes with vascular diseaseHereditary thrombophilia

Clinical Precautions

PrecautionsIncreased risk of thromboembolic disorders (e.g., MI, stroke, VTE), Hepatic neoplasia risk, Elevated blood pressure, Gallbladder disease, Carbohydrate/lipid metabolic effects, Headache (including migraine), Uterine bleeding irregularities, Risk of pregnancy if missed pills
Food/DietaryNo specific food interactions have been reported with OPILL. Grapefruit juice does not affect norgestrel metabolism. However, taking the pill with food may reduce nausea if it occurs.

Clinical Tips & Counseling

Clinical PearlsOPILL is a progestin-only oral contraceptive containing norgestrel 0.075 mg. It must be taken at the same time daily; a delay of more than 3 hours requires backup contraception for 48 hours. Efficacy may be reduced with concurrent enzyme-inducing drugs (e.g., rifampin, certain anticonvulsants). Irregular bleeding is common and not a sign of reduced efficacy, but pregnancy should be ruled out if no withdrawal bleed occurs. OPILL does not increase thromboembolic risk and is safe for use in patients with contraindications to estrogen, including hypertension, migraine with aura, smoking >35 years, and history of thromboembolism.
Patient AdviceTake one pill at the same time every day without missing doses. · If you are more than 3 hours late taking a pill, use a backup birth control method (like condoms) for the next 48 hours. · OPILL does not protect against sexually transmitted infections; use condoms for STI prevention. · Irregular spotting or bleeding is common, especially in the first few months; do not stop taking the pill. · If you experience severe lower abdominal pain, heavy bleeding, or symptoms of ectopic pregnancy, seek medical attention immediately. · Tell your healthcare provider if you are taking any other medications, including over-the-counter drugs and herbal supplements. · If you vomit within 2 hours after taking a pill, take another pill as soon as possible and use backup contraception for 48 hours.

OPILL Interactions

Loading safety data…

This overview is compiled from peer-reviewed clinical sources and FDA labeling. It's here to support — not replace — clinical judgment. Always verify dosing against your institution's current protocols before prescribing.

On this page

Mechanism of ActionDosing & administrationUse during pregnancyWarnings & precautionsDrug interactions

External sources

DailyMed (NIH) PubMed OpenFDA