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Structural formula
Structure of clorazepate
Non-proprietary name Clorazepate
other names
  • 9-chloro-3-oxo-6-phenyl-2,5-diazabicyclo [5.4.0] undeca-5,8,10,12-tetraene-4-carboxylic acid ( IUPAC )
  • 7-chloro-2,3-dihydro-2-oxo-5-phenyl-1 H -1,4-benzodiazepin-3-carboxylic acid
  • Chlorazepic acid
Molecular formula
  • C 16 H 11 ClN 2 O 3 ( chlorazepic acid )
  • C 16 H 10 ClKN 2 O 3 ( chlorazepate monopotassium salt )
  • C 16 H 10 ClKN 2 O 3 KOH ( chlorazepate dipotassium salt )
External identifiers / databases
CAS number
  • 23887-31-2 ( chlorazepic acid )
  • 5991-71-9 ( chlorazepate monopotassium salt)
  • 57109-90-7 ( chlorazepate dipotassium salt )
EC number 245-926-8
ECHA InfoCard 100,041,737
PubChem 2809
ChemSpider 2707
DrugBank DB00628
Wikidata Q418850
Drug information
ATC code

N05 BA05

Drug class

Tranquilizers , benzodiazepines

Molar mass
  • 314.72 g · mol -1 (Clorazepinsäure)
  • 368.81 g · mol -1 (clorazepate monopotassium salt)
  • 408.92 g · mol -1 (clorazepate dipotassium salt)
pK s value

3.5; 12.5


freely soluble in water (chlorazepate dipotassium salt)

safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS hazard labeling
no classification available
Toxicological data
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Chemically, clorazepate (clorazepinic acid) belongs to the benzodiazepine class of substances and is a drug ( tranquilizer ) from the group of psychotropic drugs . The acid forms a hydrate (geminal diol) by adding water to the carbonyl group (C-2). The hydroxyl groups are weakly acidic (pK s 12.5), so that chlorazepic acid forms a dipotassium salt (dipotassium chlorazepate), which is commonly used in drugs.

Clinical information

Clorazepate is primarily prescribed as a tranquilizer and agent against anxiety and panic attacks, but also as a sleep aid if the benzodiazepine effect is also desired the day after. Clorazepate can also be used in inpatient alcohol withdrawal , as it counteracts seizures and generally facilitates withdrawal. Even barbiturate-dependent patients are often switched to chlorazepate or diazepam for withdrawal .

Like all benzodiazepines, chlorazepate has a primary potential for dependence ( see also: Abuse of benzodiazepines ).

Pharmacological properties

Although chlorazepate is a benzodiazepine in terms of its chemical structure, the substance itself is hardly responsible for the benzodiazepine effect due to its low receptor affinity : Clorazepate binds slightly to the receptors, only its main metabolite northazepam (desmethyldiazepam) is responsible for the effect. The transformation takes place in the stomach shortly after ingestion. This makes clorazepate a prodrug .

Another effective metabolite of chlorazepate is oxazepam , which, like nordazepam, is also available as a medicinal substance. Due to the active metabolites, it can be expected that the spectrum of activity of clorazepate roughly corresponds to that of diazepam, since this is also converted into nordazepam and oxazepam. The half-life of nordazepam is 36 to 200 hours. Due to its slow breakdown in the body, it accumulates like other benzodiazepines with a long half-life. Clorazepate is only taken up to a small extent orally.

The plasma half-life of clorazepate is two hours, that of the active metabolites is about 60 hours, resulting in a duration of action of about 48 hours. N-desmethyldiazepam reaches its steady-state concentration after 6-11 days.

Dosage forms, dosage

In Germany and Switzerland, clorazepate is available as dipotassium salt (dipotassium chlorazepate ) under the trade name Tranxilium in doses of 5 mg to 50 mg per capsule or tablet. There is also a liquid form intended for injection. The manufacturer for Germany is the pharmaceutical company Sanofi . There are no generics available in Germany.

The international trade name is Tranxene ( Tranxillium in Germany), the manufacturer is Abbott Laboratories .


Clorazepate (acid and dipotassium salt) is listed as a marketable and prescribable substance in BtMG 1981 Annex III (to Section 1, Paragraph 1).

Individual evidence

  1. a b c d Entry on chlorazepic acid. In: Römpp Online . Georg Thieme Verlag, accessed on June 29, 2019.
  2. ^ A b c The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals , 14th Edition (Merck & Co., Inc.), Whitehouse Station, NJ, USA, 2006; P. 404, ISBN 978-0-911910-00-1 .
  3. This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  4. ^ A b N. Sussman: Treating anxiety while minimizing abuse and dependence. In: The Journal of clinical psychiatry. Vol. 54 Suppl, May 1993, pp. 44-51, PMID 8099577 .
  5. a b c Michael Freissmuth, Stefan Offermanns, Stefan Böhm: Pharmacology and Toxicology: From the Molecular Basics to Pharmacotherapy. Springer Science & Business Media, 2012. ISBN 978-3-642-12353-5 , pp. 267ff.
  6. Hans-Hasso Frey, Wolfgang Löscher, Felix R. Althaus: Textbook of pharmacology and toxicology for veterinary medicine: 131 tables, Enke veterinary medicine. Georg Thieme Verlag, 2010. ISBN 978-3-8304-1079-9 . P. 146.