General Information

Classification: Downer/Sedative/Anxiolytic


The first benzodiazepine, Chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955, and made available in 1960 by Hoffmann–La Roche, which has also marketed diazepam (Valium) since 1963.

Source: Shorter E (2005). "Benzodiazepines". A Historical Dictionary of Psychiatry. Oxford University Press. pp. 41–2. ISBN 0-19-517668-5.


Comparison of benzodiazepines
Chemical name (brand name) Half-Life [Active Metabolites] Dose Equiv. of 10mg Diazepam (Oral) Class
Alprazolam (Xanax) 6 - 12 hours 0.5 mg Anxiolytic
Bromazepam (Lexotan, Lexomil) 10 - 20 hours 5 - 6 mg Anxiolytic
Chlordazepoxide (Librium) 5 - 30 hours [36 - 200 hours] 25 mg Anxiolytic
Clobazam (Frisium) 12 - 60 hours 20 mg Anxiolytic
Clonazepam (Klonopin) 18 - 50 hours 0.5 mg Anxiolytic
Clorazepate (Tranxene) [36 - 200 hours] 15 mg Anxiolytic
Diazepam (Valium) 20 - 100 hours [36 - 200 hours] 10 mg Anxiolytic
Estazolam (ProSom, Nuctalon) 10 - 24 hours 1 - 2 mg Hypnotic
Flunitrazepam (Rohypnol) 18 - 26 hours [36 - 200 hours] 1 mg Hypnotic
Flurazepam (Dalmane) [40 - 250 hours] 15 - 30 mg Hypnotic
Halazepam (Paxipam) [30 - 100 hours] 20 mg Anxiolytic
Ketazolam (Paxipam) 30 - 100 hours [36 - 200 hours] 15 - 30 mg Anxiolytic
Loprazolam (Dormonoct) 6 - 12 hours 1 - 2 mg Hypnotic
Lorazepam (Ativan) 10 - 20 hours 1 mg Anxiolytic
Lormetazepam (Noctamid) 10 - 12 hours 1 - 2 mg Hypnotic
Medazepam (Nobrium) 36 - 200 hours 10 mg Anxiolytic
Nitrazepam (Mogadon) 15 - 38 hours 10 mg Hypnotic
Nordazepam (Nordaz) 36 - 200 hours 10 mg Anxiolytic
Oxazepam (Serax) 4 - 15 hours 20 mg Anxiolytic
Prazepam (Centrax) [36 - 200 hours] 10 - 20 mg Anxiolytic
Quazepam (Doral) 25 - 100 hours 20 mg Hypnotic
Temazepam (Restoril) 8 - 22 hours 20 mg Hypnotic
Triazolam (Halcion) 2 hours 0.5 mg Hypnotic
Non-benzodiazepines commonly referred to as Z-drugs
Chemical name (brand name) Half-Life [Active Metabolites] Dose Equiv. of 10mg Diazepam (Oral) Class
Zaleplon (Sonata) 2 hours 20 mg Hypnotic
Zolpidem (Ambien) 2 hours 20 mg Hypnotic
Zopiclone (Imovane) 5 - 6 hours 15 mg Hypnotic
Eszopiclone (Lunesta) 6 hours 3 mg Hypnotic

Harm Reduction

  • Avoid driving and operating machinery
  • Recommended time (pauses) between using the substance
  • Addiction potential - High
  • Risk of blackouts
  • Risk of death when mixed with alcohol or other drugs. An extremely high percentage of drug-related deaths are due to mixing benzos with other drugs, especially opiates and alcohol.
  • Mental illness
  • Heart issues
  • CNSCentral Nervous System depressant when mixed with other drugs

Chemistry and Pharmacology

The term benzodiazepine is the chemical name for the heterocyclic ring system, which is a fusion between the benzene and diazepine ring systems. Under Hantzsch–Widman nomenclature, a diazepine is a heterocycle with two nitrogen atoms, five carbon atom and the maximum possible number of cumulative double bonds. The "benzo" prefix indicates the benzene ring fused onto the diazepine ring. Benzodiazepine drugs are substituted 1,4-benzodiazepines, although the chemical term can refer to many other compounds that do not have useful pharmacological properties. Different benzodiazepine drugs have different side groups attached to this central structure. The different side groups affect the binding of the molecule to the GABAA receptor and so modulate the pharmacological properties. Many of the pharmacologically active "classical" benzodiazepine drugs contain the 5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one substructure. Nonbenzodiazepines also bind to the benzodiazepine binding site on the GABAA receptor and possess similar pharmacological properties. While the nonbenzodiazepines are by definition structurally unrelated to the benzodiazepines, both classes of drugs possess a common pharmacophore , which explains their binding to a common receptor site


  • 2-keto compounds:
chlordiazepoxide, clorazepate, diazepam, flurazepam, halazepam, prazepam, and others.
  • 3-hydroxy compounds:
lorazepam, lormetazepa,oxazepam, temazepam
  • 7-nitro compounds:
clonazepam, flunitrazepam, nimetazepam, nitrazepam
  • Triazolo compounds:
adinazolam, alprazolam, estazolam, triazolam
  • Imidazo compounds
climazolam, loprazolam, midazolam


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