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Ethinyl Estradiol

Hormonal Contraceptiveprescriptionoral · inferred

Synthetic estrogen (17-alpha-ethinyl-17-beta-estradiol) that is the estrogen component of nearly all combined oral contraceptives and the vaginal ring/patch. 17-alpha-ethinyl substitution blocks the primary oxidative site, giving ~40x oral potency over estradiol and a ~24 h plasma half-life. Undergoes extensive first-pass 2-hydroxylation (CYP3A4, CYP1A2) and phenolic sulfation (SULT1E1) and glucuronidation (UGT1A1). Raises hepatic SHBG, CRP, and clotting factor synthesis (VTE risk). Typical contraceptive doses 10-35 mcg/day.

Projected serum levels — 30 mcg (≈ 0.030 mg), once daily

Ethinyl Estradiol
Ethinyl Estradiol modeled serum levels, 30 mcg (≈ 0.030 mg) once daily over 15 days Population-based pharmacokinetic estimate. Steady state reached after approximately 2 days. 0 0.25 0.50 0.75 1 Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule ≈ steady state · day 2
Ethinyl Estradiol modeled serum levels with a loading dose of 52.6 mcg, then 30 mcg (≈ 0.030 mg) once daily The first dose is larger so levels approach steady state faster. 0 0.25 0.50 0.75 1 Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule

Maintenance schedule: 30 mcg (≈ 0.030 mg) once daily (oral).

Loading schedule: 52.6 mcg on day 1, then 30 mcg (≈ 0.030 mg) once daily — reaching therapeutic levels sooner.

Modeled steady state after ~2 days: peak ≈ 0.021 mg, trough ≈ 0.010 mg body load. Population-based estimate over 15 days for a reference dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
Hormonal Contraceptive
Route modeled
Oral
Model confidence
inferred
Half-life
20 h
Common dose
30 mcg (≈ 0.030 mg)
Suggested maximum
50 mcg/day
Reference dose range
0.020–50 mcg (single dose)
Suggested cadence
once daily
Validated against
0.030 mg oral — Cmax 0.000 mg/L at 1.5 h

Documented interactions

  • danger
    7-Hydroxymitragynine (7-OH) + Ethinyl Estradiol CYP inhibition

    Ethinyl Estradiol reversible_inhibitor of CYP3A4 predicted to change 7-Hydroxymitragynine (7-OH) AUC by ~2.20x

  • danger
    Alfuzosin (Uroxatral) + Ethinyl Estradiol CYP inhibition

    Ethinyl Estradiol reversible_inhibitor of CYP3A4 predicted to change Alfuzosin (Uroxatral) AUC by ~3.33x

  • danger
    Alprazolam (Xanax) + Ethinyl Estradiol CYP inhibition

    Ethinyl Estradiol reversible_inhibitor of CYP3A4 predicted to change Alprazolam (Xanax) AUC by ~3.33x

  • danger
    Amlodipine (Norvasc) + Ethinyl Estradiol CYP inhibition

    Ethinyl Estradiol reversible_inhibitor of CYP3A4 predicted to change Amlodipine (Norvasc) AUC by ~3.33x

  • danger
    Anastrozole (Arimidex) + Ethinyl Estradiol CYP inhibition

    Ethinyl Estradiol reversible_inhibitor of CYP3A4 predicted to change Anastrozole (Arimidex) AUC by ~2.68x

  • danger
    Astaxanthin + Ethinyl Estradiol CYP inhibition

    Ethinyl Estradiol reversible_inhibitor of CYP3A4 predicted to change Astaxanthin AUC by ~3.33x

Serum checks 486 modeled interaction pairings for ethinyl estradiol across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Ethinyl estradiol and conjugated equine estrogens: pharmacokinetics and endocrine pharmacology Stanczyk FZ et al. · Contraception, 2013 DOI

    Definitive PK review of ethinyl estradiol establishing oral bioavailability ~43%, terminal half-life ~24h, extensive first-pass metabolism via CYP3A4 2-hydroxylation and SULT1E1/UGT1A1 conjugation.

  2. Pharmacokinetics of ethinylestradiol Goldzieher JW, Brody SA · American Journal of Obstetrics and Gynecology, 1990 DOI

    Classic PK characterization of ethinyl estradiol documenting enterohepatic recirculation and wide interindividual variability.

  3. Interactions between hormonal contraception and antiepileptic drugs Reimers A et al. · Seizure, 2015 DOI

    Review of CYP3A4 inducer interactions demonstrating 40-80% EE AUC reductions from enzyme-inducing anticonvulsants with contraceptive failure implications.

3 published studies referenced in the app, each with a plain-language summary.