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GBL (Gamma-Butyrolactone)

Depressantoral · inferred

Industrial solvent and prodrug to GHB. Rapidly converted to GHB by serum paraoxonase (lactonase) enzymes within minutes. More lipophilic than GHB, resulting in faster absorption, higher bioavailability, and more potent effects per dose. Shorter onset but similar duration to GHB (1.5-3h). Same dangers as GHB: narrow dose-response curve, respiratory depression, and lethal interaction with alcohol/opioids.

Projected serum levels — 1 mL (≈ 1.1k mg), as needed (shown daily)

GBL (Gamma-Butyrolactone) (precursor)GHB (Gamma-Hydroxybutyrate)
GBL (Gamma-Butyrolactone) modeled serum levels, 1 mL (≈ 1.1k mg) as needed (shown daily) over 15 days Population-based pharmacokinetic estimate. Steady state reached after approximately 1 days. 0 250 500 750 1k Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule ≈ steady state · day 1
GBL (Gamma-Butyrolactone) modeled serum levels with a loading dose of 1.3 mL, then 1 mL (≈ 1.1k mg) as needed (shown daily) The first dose is larger so levels approach steady state faster. 0 250 500 750 1k Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule

Maintenance schedule: 1 mL (≈ 1.1k mg) as needed (shown daily) (oral).

Loading schedule: 1.3 mL on day 1, then 1 mL (≈ 1.1k mg) as needed (shown daily) — reaching therapeutic levels sooner.

Modeled steady state after ~1 days: peak ≈ 13.6 mg, trough ≈ 0.000 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
Depressant
Route modeled
Oral
Model confidence
inferred
Half-life
3.1 h
Common dose
1 mL (≈ 1.1k mg)
Reference dose range
0.50–2 mL (single dose)
Suggested cadence
as needed (shown daily)

Documented interactions

  • danger
    1,4-BDO (1,4-Butanediol) + GBL (Gamma-Butyrolactone) Contraindicated

    Both 1,4-BDO and GBL convert to GHB. GBL converts within minutes; 1,4-BDO takes 30-90 min. Co-administration stacks two delayed GHB peaks at unpredictable times.

  • danger
    Codeine + GBL (Gamma-Butyrolactone) Contraindicated

    GBL converts to GHB, a CNS depressant. Codeine is metabolized to morphine. Combined respiratory depression is dangerous.

  • danger
    Ethanol (Alcohol) + GBL (Gamma-Butyrolactone) Contraindicated

    GBL is a prodrug to GHB. Both GHB and alcohol are CNS depressants acting on GABA. Combined respiratory depression can be fatal. GBL faster onset and higher bioavailability makes this even more…

  • danger
    Morphine + GBL (Gamma-Butyrolactone) Contraindicated

    GBL converts to GHB, a CNS depressant. Combined with opioids, additive respiratory depression can be rapidly fatal.

  • danger
    Oxycodone + GBL (Gamma-Butyrolactone) Contraindicated

    GBL converts to GHB, a CNS depressant. Combined with opioids, additive respiratory depression can be rapidly fatal.

  • moderate
    GHB (Gamma-Hydroxybutyrate) + GBL (Gamma-Butyrolactone) Stacked effects

    GBL (Gamma-Butyrolactone) and GHB (Gamma-Hydroxybutyrate) both push the gaba b and ghb receptor in the same direction.

Serum checks 10 modeled interaction pairings for gbl (gamma-butyrolactone) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Behavioral effects and pharmacokinetics of gamma-hydroxybutyrate (GHB) precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) in baboons Goodwin AK et al. · Psychopharmacology, 2009 DOI

    Primate PK study of GBL showing rapid conversion to GHB via lactonase, higher peak GHB levels than equimolar GHB dosing, and pharmacokinetic basis for GBL increased potency.

  2. Gamma-hydroxybutyric acid (GHB), 1,4-butanediol (1,4BD), and gamma-butyrolactone (GBL) intoxication: A state-of-the-art review Busardo FP et al. · Regulatory Toxicology and Pharmacology, 2023 DOI

    Comprehensive review of GBL/GHB clinical toxicology including rapid lactonase-mediated conversion, dose-dependent nonlinear GHB elimination, and fatal case analyses.

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