Barbiturates – Sedative Hypnotics

00:01 Let's move on to the barbiturates. The barbiturates receptors, the GABA A receptors are also present in the brain and we see those ones often in the reticular activating system of the brain. Barbiturates may also antagonize glutamic acid.

00:17 Barbiturates are not antagonized by flumazenil. So think about this. Look where flumazenil is and where it binds to the gamma subunit and then take a look at where the receptor binding site is for barbiturates. They are quite far apart.

00:31 Flumazenil is an antidote to benzodiazepine poisoning or overdose. It does not work against the barbiturates.

00:41 Barbiturates also cause increased flow of chloride through the channel but it does so a little bit differently than benzodiazepines. It helps the GABA to inhibit the gamma subunit. So the gamma subunit is now inhibited and it opens up but it increases the duration of chloride flow through opening. And so that's different than the benzos. The benzos increase frequency, barbiturates increase duration. Barbiturates are binding on both the alpha and the beta units. And through many types of receptors it exerts many levels of sedation throughout the brain.

01:25 We often use barbiturates for induction of anesthesia. So thiopental is the prototypical drug and the one that you should remember. In terms of the benzodiazepines, we also use diazepam and midazolam for induction. I personally use lorazepam in the intensive care unit. Seizure control is excellant with the barbiturate phenobarbital, and we've used it many times for status epilepticus where we can't get control of patients.

01:52 It's sort of our go to strong drug for seizure control.