Meclonazepam

Meclonazepam is a benzodiazepine for GABA-A receptor binding studies. Purity ≥98% (HPLC).

Product Name: Meclonazepam Synonyms: 3-Methylclonazepam; Ro 11-3128; 5-(2-chlorophenyl)-3-methyl-7-nitro-1,3-dihydro-2H-1,4-benzodiazepin-2-one12

General Description: Meclonazepam is a synthetic, psychoactive molecule belonging to the benzodiazepine class.135 Structurally, it is heavily related to the widely prescribed pharmaceutical clonazepam, differing only by the addition of a methyl group at the 3-position of the diazepine ring.23 Originally synthesized by Hoffmann-La Roche in the 1970s, it is a highly unique compound that was investigated not only for its sedative and anxiolytic properties but also for distinct anti-parasitic (schistosomicidal) effects.245 Ultimately, its profound sedating nature precluded its clinical viability as an antiparasitic drug.235 More recently, meclonazepam has emerged on the illicit market as a novel psychoactive substance (NPS) and designer benzodiazepine.245

In analytical, clinical, and forensic toxicology, meclonazepam is utilized as a fundamental reference standard.235 It is essential for the calibration of analytical instrumentation (such as LC-MS/MS, GC-MS, and NMR) and the development of screening methodologies to identify and quantify the substance in seized materials, adulterated illicit street drugs, or biological matrices (e.g., whole blood, plasma, urine).14

Technical Information:

• CAS Number: 58662-84-3 (S-enantiomer) / 67027-56-9 (Racemic mixture)24
• Molecular Formula: C₁₆H₁₂ClN₃O₃45
• Formula Weight: 329.74 g/mol45
• SMILES: CC1C(=O)NC2=C(C=C(C=C2)N+[O-])C(=N1)C3=CC=CC=C3Cl
• InChI Key: LMUVYJCAFWGNSY-UHFFFAOYSA-N (Racemate) / LMUVYJCAFWGNSY-VIFPVBQESA-N (S-enantiomer)14
• Formulation: Typically supplied as a neat white-to-yellow crystalline solid or as a certified reference material solution (e.g., 1 mg/mL or 100 µg/mL in methanol).145

Biological Action: Meclonazepam acts as a highly potent positive allosteric modulator (PAM) at central GABA_A receptors.145 By enhancing the inhibitory signaling of the neurotransmitter gamma-aminobutyric acid (GABA), it elicits classical benzodiazepine effects, including profound sedation, anxiolysis, hypnosis, muscle relaxation, and amnesia.24 Separately from its GABAergic activity, meclonazepam uniquely induces rapid intracellular calcium influx and spastic paralysis in the parasitic worm Schistosoma mansoni (the causative agent of schistosomiasis), leading to tegumental disruption and parasite death.245

Regulatory and Safety Information:

• Intended Use: This product is intended strictly for use as an analytical reference standard for forensic, toxicological, and academic research purposes.135
• Warning: This product is highly potent, carries a severe risk of central nervous system depression, physiological dependence, and fatal overdose (especially when combined with other depressants like alcohol or opioids).145 It is not for human or veterinary use.456
• Legal Status: The regulatory status of meclonazepam varies globally.235 In the United Kingdom, it is controlled as a Class C substance under the Misuse of Drugs Act.235 In the United States, meclonazepam is not explicitly scheduled at the federal level; however, many individual states have placed it into Schedule IV (alongside other benzodiazepines) or Schedule I of their controlled substance lists.245 Furthermore, it is strictly controlled in numerous European nations under blanket bans on designer benzodiazepines.235 Procurement may require relevant local or institutional licenses.235 Handling should only occur within professional laboratory environments using appropriate Personal Protective Equipment (PPE) such as safety glasses, chemical-resistant gloves, and a laboratory coat.24