3-Hydroxyphenazepam
3-Hydroxyphenazepam is a designer benzodiazepine and an active metabolite of phenazepam. It is sold as a research chemical and produces the sedative, anxiolytic and amnestic effects typical of the class, with a long duration. Human data is essentially limited to its role as a phenazepam metabolite and to user reports.
01 Overview
3-Hydroxyphenazepam is the 3-hydroxylated metabolite of phenazepam, a long-acting benzodiazepine of Soviet origin. It reaches the grey market as a standalone research chemical in powder, pellet and blotter forms. Like other 2'-halogenated benzodiazepines it is highly potent by weight, and small differences in dosing translate into large differences in effect.
Reported effects overlap with other potent designer benzodiazepines: heavy sedation, muscle relaxation, anxiolysis and marked anterograde amnesia. Because it is long-acting and often mislabelled or unevenly dosed in grey-market products, accidental over-sedation and next-day carryover are common complaints in user reports. There is no clinical characterisation of it as a standalone drug in humans.
02 Mechanism
Positive allosteric modulator at the benzodiazepine site of the GABA-A receptor, enhancing GABA-mediated chloride conductance and producing central nervous system depression.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Light | 0.1–0.3 mg | Oral | Grey-market products are frequently misdosed; volumetric dosing is safer than eyeballing. |
| Common | 0.3–0.7 mg | Oral | Long duration means redosing readily causes over-sedation. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| AnxiolysisReduction in anxiety and psychological tension, consistent with the benzodiazepine class. | Marked | Anecdotal | |
| SedationDrowsiness and reduced arousal, often lasting into the following day. | Strong | Anecdotal | |
| Muscle relaxationReduced muscle tension typical of potent benzodiazepines. | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Dependence and withdrawalTolerance builds quickly and daily use leads to physical dependence; abrupt cessation can precipitate rebound anxiety, insomnia and seizures. | Severe | Common with regular use | Anecdotal | |
| Blackouts and amnesiaAnterograde amnesia and blackout periods, especially at higher doses or combined with alcohol. | Moderate | Common at higher doses | Anecdotal | |
| Additive respiratory depressionCombined with opioids, alcohol or other depressants, respiratory depression can become dangerous. | Life-threatening | With CNS depressants | Observational |