Library
4-Methoxybutyrfentanyl
4-MeO-BF is a highly potent fentanyl analogue first identified in Europe in 2015. Fatal blood concentrations have ranged 2-18 ng/mL, only modestly lower than fentanyl itself. Street material varies wildly in purity; volumetric dosing with a 1 mg/mL (or weaker) solution and a 0.01 mL oral syringe is strongly advised - never eyeball powder. Naloxone 0.4-2 mg IV/IM will reverse toxicity, but its shorter half-life means repeat doses or continuous infusion may be required (re-narcotization common after 30-60 minutes). Always monitor at least 2 hours after last dose.
Also known as: 4-meo-bf, Para-Methoxybutyrylfentanyl, P-MeO-butyrylfentanyl, 4-Methoxy-butyrylfentanyl
Classification
- Chemical: Anilidopiperidine
- Chemical: Opioid
- Psychoactive: Depressant
- Tag: Anilinopiperidine
- Tag: Habit-Forming
- Tag: Research-Chemical
Effects
- Anxiolysis
- Pain Relief
- Sedation
- Physical Euphoria
- Respiratory Depression
- Itchiness
- Cognitive Euphoria
- Compulsive Redosing
- Euphoria
- Anxiety Suppression
- Dissociation
- Sadness
- Dulled Perception
- Open Eye Visuals
- Sound Dampening
Routes of Administration
Oral
Dosage
- Threshold: <50 ug (unverified)
- Light: 50-100 ug
- Common: 100-300 ug
- Strong: 300-600 ug
- Heavy: >600 ug
Duration
- Onset: 0.08-0.25 h
- Peak: 0.25-0.75 h
- Offset: 0.25-0.75 h
- After Effects: 60-120 h
- Total Duration: 30-120 h
Insufflated
Dosage
- Threshold: <25 ug (unverified)
- Light: 25-75 ug
- Common: 75-200 ug
- Strong: 200-400 ug
- Heavy: >400 ug
Duration
- Onset: 0.02-0.03 h
- Peak: 0.25-0.75 h
- Offset: 0.25-0.75 h
- After Effects: 30-120 h
- Total Duration: 30-90 h
Intravenous
Dosage
- Threshold: <10 ug (allergy test)
- Light: 10-25 ug
- Common: 25-75 ug
- Strong: 75-150 ug
- Heavy: >150 ug
Duration
- Onset: 0.01-0.02 h
- Peak: 0.25-0.75 h
- Offset: 0.25-0.75 h
- After Effects: 30-120 h
- Total Duration: 20-60 h
Harm Reduction
Check interactions before mixing substances, pay attention to dose spacing and hydration, and treat all dosage guidance as approximate rather than guaranteed safe.
Sources
Substance data is aggregated from the following public harm-reduction and reference sources.
Links
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