Diazepam

Diazepam
ATC Code N05BA01
Formula C16H13ClN2O
Molar Mass (g·mol−1) 284,74
Physical State solid
Melting Point (°C) 125–126
PKS Value 3,4
CAS Number 439-14-5
PUB Number 3016
Drugbank ID DB00829
Solubility sparingly soluble in water

Basics

Diazepam is a drug from the group of benzodiazepines. Within this group, diazepam belongs to the long-acting representatives. It has sedative, antianxiety and anticonvulsant properties. It is used for the treatment of anxiety and epilepsy and for premedication before surgical procedures. As with all benzodiazepines, there is a risk of dependence with prolonged use of diazepam. Diazepam is most commonly given in tablet form, but can also be given in other forms. Diazepam is subject to a strict prescription requirement.

Pharmacology

Pharmacodynamics

The action of diazepam is due to what is known as allosteric modulation of the GABA-A receptor in the neurons of the brain and spinal cord. This means that diazepam does not bind directly to the binding site of GABA, but to a separate site on the receptor. This increases the affinity of GABA (gammaaminobutyric acid, an important inhibitory neurotransmitter) for the receptor, making it more likely to open. This results in the depressant effect of diazepam.

Pharmacokinetics

Diazepam is absorbed in the gastrointestinal tract and reaches maximum plasma concentration after approximately 1-1.5 hours. Plasma protein binding is 98-99%. Diazepam is degraded in the liver by the enzymes of the CYP450 system. The two enzymes CYP3A4 and CYP2C19 are mainly involved. The resulting metabolites are glucuronidated and almost entirely excreted in the urine. The elimination half-life is 1-2 days.

Drug Interactions

Concomitant use with drugs that are also cleared by the CYP3A4 or CYP2C19 enzymes may result in increased levels of diazepam. These include: Cimetidine, omeprazole, disulfiram, ketoconazole, fluvoxamine and fluoextine. Combination with drugs that have the same or similar effect on the CNS (antidepressants, sedatives, neuroleptics, antiepileptics, anxiolytics, HIV protease inhibitors) should also be avoided at all costs. Furthermore, diazepam must not be combined with levodopa, theophylline, phenytoin, phenobarbital and muscle relaxants.

Toxicity

Side effects

Common side effects of diazepam include:

  • Headache
  • nausea
  • decreased responsiveness
  • gastrointestinal distress
  • difficulty breathing
  • Hypotension
  • Urinary retention

There is a great potential for dependence when benzodiazepines are taken.

Toxicological data

LD50 (rat, oral): 249 mg-kg-1

Markus Falkenstätter

Markus Falkenstätter
Author

Markus Falkenstätter ist Autor zu pharmazeutischen Themen in der Medizin-Redaktion von Medikamio. Er befindet sich im letzten Semester seines Pharmaziestudiums an der Universität Wien und liebt das wissenschaftliche Arbeiten im Bereich der Naturwissenschaften.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer
Lector

Stefanie Lehenauer ist seit 2020 freie Autorin bei Medikamio und studierte Pharmazie an der Universität Wien. Sie arbeitet als Apothekerin in Wien und ihre Leidenschaft sind pflanzliche Arzneimittel und deren Wirkung.

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