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Dexamethasone (Decadron)

Corticosteroidprescriptionoral · inferred

Long-acting potent glucocorticoid with biologic half-life of 36-54 hours (far exceeding plasma half-life of 4 hours) due to sustained genomic effects. ~25x potency of hydrocortisone on per-weight basis. Bioavailability 60-80%; peak plasma 1 hour. Metabolized by CYP3A4; ~77% plasma protein bound. Eliminated <10% renally. Used for inflammatory, autoimmune, neoplastic conditions, cerebral edema, immune suppression. Long duration permits once-daily dosing.

Projected serum levels — 4 mg, once daily

Dexamethasone (Decadron)
Dexamethasone (Decadron) modeled serum levels, 4 mg once daily over 15 days Population-based pharmacokinetic estimate. Steady state reached after approximately 1 days. 0 1.3 2.5 3.8 5 Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule ≈ steady state · day 1

Maintenance schedule: 4 mg once daily (oral).

Modeled steady state after ~1 days: peak ≈ 2.5 mg, trough ≈ 0.055 mg body load. Population-based estimate over 15 days for a 4 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
Corticosteroid
Route modeled
Oral
Model confidence
inferred
Half-life
4 h
Common dose
4 mg
Suggested maximum
40 mg/day
Reference dose range
0.50–40 mg (single dose)
Suggested cadence
once daily
Validated against
4 mg oral — Cmax 0.070 mg/L at 1.5 h

Documented interactions

  • contraindicated
    Clarithromycin (Biaxin) + Dexamethasone (Decadron) CYP inhibition

    Clarithromycin (Biaxin) mechanism_based of CYP3A4 predicted to change Dexamethasone (Decadron) AUC by ~6.54x

  • contraindicated
    Diltiazem + Dexamethasone (Decadron) CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Dexamethasone (Decadron) AUC by ~6.54x

  • contraindicated
    Efavirenz (Sustiva) + Dexamethasone (Decadron) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Dexamethasone (Decadron) AUC by ~0.13x

  • contraindicated
    Grapefruit (whole fruit) + Dexamethasone (Decadron) CYP inhibition

    Grapefruit (whole fruit) mechanism_based of CYP3A4 predicted to change Dexamethasone (Decadron) AUC by ~6.54x

  • contraindicated
    Grapefruit Juice + Dexamethasone (Decadron) CYP inhibition

    Grapefruit Juice mechanism_based of CYP3A4 predicted to change Dexamethasone (Decadron) AUC by ~6.54x

  • contraindicated
    Paxlovid (Nirmatrelvir/Ritonavir) + Dexamethasone (Decadron) CYP inhibition

    Paxlovid (Nirmatrelvir/Ritonavir) mechanism_based of CYP3A4 predicted to change Dexamethasone (Decadron) AUC by ~6.54x

Serum checks 296 modeled interaction pairings for dexamethasone (decadron) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Dose-dependent pharmacokinetics of dexamethasone Saris G et al. · European Journal of Clinical Pharmacology, 1990 DOI

    PK study showing dexamethasone exhibits dose-dependent kinetics; bioavailability 70-78%, plasma half-life 3.5-5 hours, CYP3A4 metabolism primary elimination pathway.

  2. Comparative Safety, Bioavailability, and Pharmacokinetics of Oral Dexamethasone, 4-mg and 20-mg Tablets, in Healthy Volunteers Under Fasting and Fed Conditions Cheng S et al. · Clinical Therapeutics, 2020 DOI

    Bioequivalence and bioavailability study demonstrating oral dexamethasone 81% bioavailability, Cmax ~64 ug/L at 2 hours, with minimal food effects; formulations bioequivalent.

  3. Pharmacokinetics of oral vs. intravenous dexamethasone in patients hospitalized with community-acquired pneumonia Siempos II et al. · Intensive Care Medicine, 2014 DOI

    RCT showing oral and IV dexamethasone bioequivalent in pneumonia patients; oral bioavailability 81%, supporting oral administration as equally effective alternative to IV.

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