What are the chemical properties of clonazepam

Structural formula
Non-proprietary name Clonazepam
other names
  • IUPAC: 5- (2-chlorophenyl) -7-nitro-1,3-dihydrobenzo [e] [1,4] diazepin-2-one
  • Latin: Clonazepamum
Molecular formula C.15H10ClN3O3
CAS number 1622-61-3
PubChem 2802
ATC code


DrugBank APRD00054
Drug information
Drug class
  • Benzodiazepine
  • Anti-epileptic
Mechanism of action

anticonvulsant effect

Prescription required: Yes, partly BtMG
Molar mass 315.71 g mol−1
Melting point

236.5-238.5 ° C [1]

safety instructions
Please note the restricted validity of the hazardous substance labeling for pharmaceuticals
GHS hazard labeling [1]
H and P phrases H: no H-phrases
P: no P-phrases[1]
EU labeling of hazardous substances [1]
R and S phrases R: no R-phrases
S: no S-phrases

2000 mg kg−1 (Mouse p.o.) [1]

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions.
Template: Infobox chemical / molecular formula search available

Clonazepam (Trade name: Rivotril, manufacturer: Roche) is a drug from the benzodiazepine group that is used to treat cerebral seizures (anticonvulsant) and anxiety disorders (anxiolytic). Psychological and physical dependence can develop after only a short period of use.


Clonazepam is rapidly absorbed after administration through the gastrointestinal tract. The maximum concentration in the blood is reached after two to three hours. Excretion is largely unchanged via the kidneys, and sometimes also via the stool. A small part is chemically converted and only then excreted. The plasma half-life is approximately 30–40 hours.[2] The proportion that is bound to the protein molecules in the blood (plasma protein binding) is 83–87%, the bioavailability is 71–76%. It works by increasing the inhibition of GABAergic nerve cells and attacks the GABAA.Receptor on.

application areas

Because of its anti-spasmodic effects, clonazepam is used to treat epilepsy. It also plays a minor role as the most important alternative drug in restless legs syndrome.[3] Since long-term treatment, as with all active substances of the benzodiazepine group, can lead to a rapid loss of effectiveness (tachyphylaxis), it is mainly used in acute treatment in Germany, mostly intravenously or intramuscularly. But it is also available in drop form and as a tablet. In addition to its antispasmodic effect, clonazepam, like all benzodiazepines, has an anxiolytic and sleep-inducing effect. Clonazepam can therefore also be used for somnambulism (night walking). In addition, it is used in many countries as the first choice for panic attacks as an anxiolytic. In addition, it should make states of derealization / depersonalization more bearable. For these psychiatric indications, however, there is no official approval in Germany, so that a corresponding use of the agent can only be considered by a specialist in individual cases.

Clonazepam is recommended for the treatment of REM sleep behavior disorder (RBD) or Schenk syndrome. Taken at bedtime will reduce muscle activity during REM sleep. In this context, even with long-term use, there is hardly any development of tolerance or loss of effectiveness, which is important in the often chronic course of the disease.[4]

Use during pregnancy and breastfeeding

Animal studies have shown undesirable effects on the fetus. Therefore, the drug should only be used during pregnancy if it is absolutely necessary. However, clonazepam should not be stopped suddenly without consulting a doctor. Clonazepam should not be used during breastfeeding because it is excreted in breast milk. If there is a compelling indication, breastfeeding should be carried out.[5]

Side effects

Corresponding to the suppression of cramps, clonazepam has a general depressant effect on the central nervous system, so that tiredness, drowsiness, fatigue, decreased muscle tension, muscle weakness, dizziness, drowsiness, balance disorders and prolonged reaction times can occur. With long-term therapy, these side effects are usually reduced due to a habituation effect. They can be partially avoided by gradually starting treatment. Other more common side effects of the central nervous system are concentration disorders, restlessness, confusion and memory disorders, which can also be associated with inappropriate behavior. The paradoxical reactions observed were excitability, irritability, aggressive behavior, nervousness, hostility, anxiety, insomnia, nightmares, and vivid dreams. Allergic symptoms such as hives, itching, skin rashes, swelling of the face and oral mucosa as well as the larynx occur rarely. Temporary hair loss, pigment changes, nausea and upper abdominal discomfort, headache, chest pain, drop in blood platelets, disorder of sexual appetite, impotence and urinary incontinence are also rare. A premature onset of the development of the genital organs has been reported in children in isolated cases. Also in individual cases, clonazepam can depress the respiratory center and lead to a reduced respiratory drive. Infants and young children can also experience increased salivation and increased production of mucus in the airways, making breathing difficult. Like all benzodiazepines, clonazepam can lead to dependence with corresponding withdrawal symptoms when the therapy is terminated.

See also

  • Benzodiazepine abuse


  1. 1,01,11,21,31,4data sheet Clonazepam at Sigma-Aldrich, accessed December 19, 2012.
  2. ↑ FDA Prescription Clonazepam (PDF)
  3. ↑ Cf. Boghen, D., L. Lamothe, R. Elie, R. Godbout, J. Montplaisir: The treatment of the restless legs syndrome with clonazepam: A prospective controlled study. In: Canadian Journal of Neurological Sciences 13 (1986), 245-247. PMID 3527387.
  4. ↑ S3 guideline Unrefreshing sleep / insomniaof the German Society for Sleep Research and Sleep Medicine (DGSM). In: AWMF online (as of 2009)
  5. ↑ Specialist information from the Swiss Medicines Compendium: Rivotril®, as of August 2005.

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