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Nexplanon / Implanon (Etonogestrel Implant)

Hormonal Contraceptiveprescriptionsubcutaneous · inferred

Subdermal etonogestrel implant (68 mg) providing contraception for up to 3 years. Releases ~60 mcg/day initially, declining to ~30 mcg/day by year 3. Most effective reversible contraceptive (>99.95%). Rapid fertility return after removal.

Projected serum levels — 1 implant (≈ 68 mg), custom (shown daily)

Nexplanon / Implanon (Etonogestrel Implant)
Nexplanon / Implanon (Etonogestrel Implant) modeled serum levels, 1 implant (≈ 68 mg) custom (shown daily) over 121 days Population-based pharmacokinetic estimate. Steady state reached after approximately 79 days. 0 125 250 375 500 Day 0 Day 30 Day 61 Day 91 Day 121 Time on a regular schedule ≈ steady state · day 79
Nexplanon / Implanon (Etonogestrel Implant) modeled serum levels with a loading dose of 3 implant, then 1 implant (≈ 68 mg) custom (shown daily) The first dose is larger so levels approach steady state faster. 0 125 250 375 500 Day 0 Day 30 Day 61 Day 91 Day 121 Time on a regular schedule

Maintenance schedule: 1 implant (≈ 68 mg) custom (shown daily) (subcutaneous).

Loading schedule: 3 implant on day 1, then 1 implant (≈ 68 mg) custom (shown daily) — reaching therapeutic levels sooner.

Modeled steady state after ~79 days: peak ≈ 412 mg, trough ≈ 412 mg body load. Population-based estimate over 121 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
Subcutaneous
Model confidence
inferred
Half-life
25 days
Common dose
1 implant (≈ 68 mg)
Suggested maximum
1 implant/day
Reference dose range
0.50–1 implant (single dose)
Suggested cadence
custom (shown daily)
Validated against
68 mg sc — Cmax 0.001 mg/L at 336 h

Documented interactions

  • contraindicated
    Carbamazepine (Tegretol) + Nexplanon / Implanon (Etonogestrel Implant) CYP induction

    Carbamazepine (Tegretol) inducer of CYP3A4 predicted to change Nexplanon / Implanon (Etonogestrel Implant) AUC by ~0.20x

  • contraindicated
    Clarithromycin (Biaxin) + Nexplanon / Implanon (Etonogestrel Implant) CYP inhibition

    Clarithromycin (Biaxin) mechanism_based of CYP3A4 predicted to change Nexplanon / Implanon (Etonogestrel Implant) AUC by ~10.00x

  • contraindicated
    Dasatinib (Sprycel) + Nexplanon / Implanon (Etonogestrel Implant) CYP inhibition

    Dasatinib (Sprycel) time_dependent_inhibitor of CYP3A4 predicted to change Nexplanon / Implanon (Etonogestrel Implant) AUC by ~5.00x

  • contraindicated
    Diltiazem + Nexplanon / Implanon (Etonogestrel Implant) CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Nexplanon / Implanon (Etonogestrel Implant) AUC by ~10.00x

  • contraindicated
    Efavirenz (Sustiva) + Nexplanon / Implanon (Etonogestrel Implant) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Nexplanon / Implanon (Etonogestrel Implant) AUC by ~0.12x

  • contraindicated
    Grapefruit (whole fruit) + Nexplanon / Implanon (Etonogestrel Implant) CYP inhibition

    Grapefruit (whole fruit) mechanism_based of CYP3A4 predicted to change Nexplanon / Implanon (Etonogestrel Implant) AUC by ~10.00x

Serum checks 249 modeled interaction pairings for nexplanon / implanon (etonogestrel implant) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Etonogestrel Implant: Pharmacokinetics, Clinical Efficacy, and Practice Recommendations Mommers E et al. · Therapeutic Drug Monitoring, 2012 DOI

    Comprehensive PK/efficacy review showing etonogestrel levels sufficient for ovulation suppression throughout 3 years, with Pearl Index of 0.0 in clinical trials.

  2. The Contraceptive Implant Rowlands S, Searle S · BMJ Clinical Evidence, 2014 DOI

    Systematic review establishing the etonogestrel implant as the most effective reversible contraceptive with a failure rate of 0.05% over 3 years.

  3. Return to Fertility After Removal of Etonogestrel Implant Makarainen L et al. · Contraception, 1998 DOI

    Found 94% of women ovulated within 3 months of implant removal, with etonogestrel elimination half-life of ~25 days post-removal.

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