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Estradiol (Oral)

HRTprescriptionoral · inferred

Bioidentical 17-beta estradiol in oral tablet form. Undergoes extensive first-pass hepatic metabolism, producing higher estrone:estradiol ratios than transdermal. Terminal half-life ~17 hours. Brands: Estrace. Standard HRT dose 0.5-2 mg/day.

Projected serum levels — 2 mg, once daily

Estradiol (Oral)
Estradiol (Oral) modeled serum levels, 2 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
Estradiol (Oral) modeled serum levels with a loading dose of 3.0 mg, then 2 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: 2 mg once daily (oral).

Loading schedule: 3.0 mg on day 1, then 2 mg once daily — reaching therapeutic levels sooner.

Modeled steady state after ~2 days: peak ≈ 0.013 mg, trough ≈ 0.006 mg body load. Population-based estimate over 15 days for a 2 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
HRT
Route modeled
Oral
Model confidence
inferred
Half-life
14 h
Common dose
2 mg
Suggested maximum
8 mg/day
Reference dose range
0.50–8 mg (single dose)
Suggested cadence
once daily
Validated against
2 mg oral — Cmax 0.000 mg/L at 5 h

Documented interactions

  • danger
    Carbamazepine (Tegretol) + Estradiol (Oral) CYP induction

    Carbamazepine (Tegretol) inducer of CYP3A4 predicted to change Estradiol (Oral) AUC by ~0.32x

  • danger
    Efavirenz (Sustiva) + Estradiol (Oral) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Estradiol (Oral) AUC by ~0.21x

  • danger
    Levothyroxine (Synthroid) + Estradiol (Oral) Protein binding

    Estradiol (Oral) may displace Levothyroxine (Synthroid) from plasma protein binding sites, transiently raising free drug concentration. This drug has a narrow therapeutic index; free concentration…

  • danger
    Phenobarbital + Estradiol (Oral) CYP induction

    Phenobarbital inducer of CYP3A4 predicted to change Estradiol (Oral) AUC by ~0.49x

  • danger
    Phenytoin (Dilantin) + Estradiol (Oral) CYP induction

    Phenytoin (Dilantin) inducer of CYP3A4 predicted to change Estradiol (Oral) AUC by ~0.49x

  • danger
    Rifampin + Estradiol (Oral) CYP induction

    Rifampin inducer of CYP3A4 predicted to change Estradiol (Oral) AUC by ~0.21x

Serum checks 254 modeled interaction pairings for estradiol (oral) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Half-Life of Estradiol in Postmenopausal Women Kuhnz W et al. · Maturitas, 1997 DOI

    Determined terminal elimination half-life of oral estradiol at 16.9 hours in postmenopausal women, with extensive first-pass conversion to estrone.

  2. Pharmacokinetic and Pharmacologic Variation Between Different Estrogen Products Kuhl H · Journal of Clinical Pharmacology, 1995 DOI

    Comprehensive comparison of estrogen formulations showing route-dependent differences in metabolism, bioavailability, and hormonal ratios.

  3. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial Rossouw JE et al. · JAMA, 2002 DOI

    Landmark WHI RCT (16,608 women) stopped early when combined oral estrogen + progestin showed increased breast cancer, CHD, stroke, and VTE risk; foundational for current HRT risk-benefit framework.

  4. Estradiol and Micronized Progesterone: A Narrative Review About Their Use as Hormone Replacement Therapy Conforti A et al. · Journal of Clinical Medicine, 2025 DOI

    Updated review of bioidentical HRT covering estradiol/progesterone pharmacology, cardiovascular safety, and advantages over non-bioidentical formulations.

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