Meclonazepam
Meclonazepam is a designer benzodiazepine originally investigated in the 1970s as an antiparasitic (schistosomicidal) agent. It is a methylated analogue of clonazepam with strong sedative, anxiolytic and muscle-relaxant activity. Sold as a research chemical, it carries the benzodiazepine class risks of dependence and additive respiratory depression with opioids or alcohol.
01 Overview
Meclonazepam was studied as a treatment for schistosomiasis but never marketed, in part because of dose-limiting sedation. It resurfaced on the research-chemical market as a recreational benzodiazepine. Human pharmacological data are limited to the old antiparasitic studies and scattered forensic and self-report accounts.
It is a single enantiomer that is notably potent and sedating; users report strong hypnotic and anxiolytic effects at low milligram doses. As with other designer benzodiazepines, the absence of quality control and the milligram-level potency make accidental overdose and dependence the principal hazards, especially in combination with other depressants.
02 Mechanism
Positive allosteric modulator at the benzodiazepine site of the GABA-A receptor, enhancing GABA-mediated inhibition.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Threshold | 0.5–1 mg | Oral | Potent; small increments matter. |
| Common | 1–2 mg | Oral | Strong sedation and anxiolysis. |
| Strong | 2–3 mg | Oral | Heavy hypnotic effect; risk of prolonged impairment. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Anxiolysis and sedationMarked reduction of anxiety with pronounced sedation. | strong | Anecdotal | |
| Muscle relaxationReduced muscle tone and coordination. | dose-dependent | Anecdotal | |
| HypnosisSleep-inducing effect used recreationally and for insomnia. | strong at higher doses | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Dependence and withdrawalTolerance and physical dependence develop; withdrawal may include seizures. | Severe | Common with regular use | Observational | |
| Additive respiratory depressionFatal breathing suppression possible with opioids or alcohol. | Life-threatening | Uncommon but potentially fatal | Observational | |
| Excess daytime sedationHangover-like drowsiness and impaired cognition the following day. | Moderate | Common | Anecdotal |