Benzodiazepines

Benzodiazepines (BNZs):
• most widely used anxiolytic due to relative safety and effectiveness
• potentiate action of gamma-aminobutyric acid (GABA) by binding to the GABA receptor-chloride channel complex  more frequent opening of chloride channels  hyperpolarisation and increased inhibition. They act by modifying action of endogenous GABA rather than mimicking its actions (barbiturates mimic its actions)
• effects CNS (sedation, reduce anxiety, promote sleep, muscle relaxation); cardiovascular (if taken IV  lower blood pressure); respiratory (weak depressants)
• indicated for anxiety, insomnia, seizure disorders
• also used to induce general anaesthesia, for muscle spasm and panic disorder
• different types of BNZ’s are share similar pharmacological properties, but which one is used for which indication will depend on pharmacokinetic properties and on the marketing by the pharmaceutical company
• contraindications – bronchopulmonary disease
• adverse effects – dependence (after 4-6 weeks), CNS depression, drowsiness, ataxia, decreased psychomotor skills, respiratory depression
• flumazenil can reverse sedative effects of benzodiazepines

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