Phenobarbital, also known as phenobarbitone in British English and by the brand name Luminal, is a long-acting psychoactive drug of the barbiturate class which produces powerful anxiolytic, hypnotic, muscle relaxant and amnesic effects. Phenobarbital is used medically as an anticonvulsant, and occasionally in the short term treatment of insomnia. Phenobarbital works in a similar fashion to benzodiazepines, however barbiturates bind to a distinct allosteric site on the GABAA receptor.
Phenobarbital molecular structure diagram from the DrugsPRO substance library.
Also known as: Pheno, Luminal, Solfoton, Phenobarb, Phenobarbitone, Sezaby, Phenobarbitol, PB
Classification
Chemical: Barbiturate
Chemical: Medicine
Psychoactive: Depressant
Tag: Anticonvulsant
Tag: Anxiolytic
Tag: GABAergic
Tag: Habit-Forming
Tag: Muscle Relaxant
Tag: Sedative
Effects
Respiratory Depression
Decreased Blood Pressure
Decreased Body Temperature
Pupil Constriction
Seizure Suppression
Sedation
Thought Deceleration
Amnesia
Motor Control Loss
Dizziness
Drowsiness
Confusion
Disinhibition
Dulled Perception
Open Eye Visuals
Double Vision
Blurred Vision
Voices
Routes of Administration
Oral
Dosage
Heavy: 300+ mg
Light: 50 – 100 mg
Common: 100 – 150 mg
Strong: 150 – 300 mg
Threshold: 25 mg
Duration
Onset: 0.25-1 h
Comeup: 1-2 h
Peak: 4-6 h
Offset: 12-24 h
After Effects: 12-24 h
Total Duration: 6-12 h
Intravenous
Dosage
Heavy: 100+ mg
Light: 15-30 mg
Common: 30-60 mg
Strong: 60-100 mg
Threshold: 10 mg
Duration
Onset: 0.08-0.17 h
Peak: 0.17-0.5 h
Offset: 4-10 h
After Effects: 10-24 h
Total Duration: 4-10 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.
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Phenobarbital - DrugsPRO substance guide
Phenobarbital: Phenobarbital, also known as phenobarbitone in British English and by the brand name Luminal, is a long-acting psychoactive drug of the barbiturate class which produces powerful anxiolytic, hypnotic, muscle relaxant and amnesic effects. Phenobarbital is used medically as an anticonvul
