Sedative-Hypnotics and Benzodiazepines

Key points

• • Sedatives reduce anxiety and excitement, while hypnotics promote sleep, and many drugs do both depending on the amount given.
• • Benzodiazepines enhance the effect of GABA at the GABA-A receptor by increasing the frequency of chloride-channel opening, which quietens neuronal firing.
• • Compared with the older barbiturates, benzodiazepines are much safer because of a ceiling effect, but they can still depress breathing dangerously, especially with opioids, alcohol or other depressants.
• • Barbiturates increase the duration of chloride-channel opening and can directly open the channel, so they depress breathing severely when taken in excess.
• • Flumazenil is a benzodiazepine antagonist that can reverse their sedation but may precipitate seizures or withdrawal, so it is not a routine antidote; long-term use of these drugs causes tolerance and dependence.