Let's talk about benzodiazepines now. We've already done an introduction. Let's move ahead.
Now benzodiazepines have a benzene ring fused to a seven membrane diazepine ring. The site of action. benzodiazepines is the thalamus midbrain ascending reticular formation which regulates our wakefulness limbic system brainstem etc the receptor that it acts on is GABA a GABA a receptor actually which has specifically benzodiazepine binding site there are two types bz1 and bz2 similar to the alpha 1 and alpha 2 and 3 in the previous videos just different names.
BZ1 is for sedation, BZ2 is for anxiolytic and cognitive impairment. It acts on both of them of course. Let's do some classification.
Benzodiazepines are divided into four groups ultra short acting, short acting, medium acting and long acting benzodiazepines. Ultra short acting benzodiazepines are triazolam and midazolam. I remember it with tri and mid.
Short acting are lorazepam and temazepam. I remember them with two short friends. One's name is Laura and the other is Tima. Laura and Tima are two short friends.
Medium acting are nitrazepam and alprazolam. Alprazolam is the commonly used Xanax for sleep. I'm sure all of you have used it.
Long acting include diazepam, and chlorodisipoxide now why are they long-acting because they produce metabolites such as desmethyldisipam or nordisipam which have a high half-life of about 40 hours so that's why they are long acting because their metabolites are long acting and they are active. Now mechanism of action we have already discussed in the previous videos just for a recap. They act on the benzodiazepine receptor on GABA-A which increases the frequency of chloride channel opening leading to hyperpolarization and thus CNS depression. An important point to remember that I already mentioned in the previous video was that benzodiazepines have no GABA mimetic effect that means it cannot go to such toxic levels to cause coma and respiratory depression.
This is a graph showing hyperpolarization. now a few words about the pharmacokinetics of benzodiazepines they can be given orally and IV they are not given intramuscularly because of their erratic absorption from this site they have a high volume of distribution and redistribution is also very much very high so they have no residual symptoms duration of action is short now metabolism some of them are metabolized in the liver and some are not metabolized in the liver now to remember which ones are metabolized in the liver and which are not which ones are not we have a mnemonic for those who are metabolized in the liver it's found a cd in the liver now you can picture a cd in a liver i know it's absurd but just you'll remember it found a CD in the liver fluorozypam a for alprazolam C for chloro dizepam now for those which are not metabolized in the liver the mnemonic is This lot is not metabolized in liver. Lot not.
This lot is not metabolized. Lorazepam, oxazepam and T4 temazepam. Now let's come to the uses of the benzodiazepines. The mnemonic for the uses is AC-diazepam. A for alcohol withdrawal as alcohol is also a CNS depressant so those people who are going through withdrawal symptoms can benefit from this conscious sedation it's a special type of sedation where the patient can cooperate during minor surgical procedures it can be used diagnostically for endoscopies and minor procedures in insomnia of course it causes sedation it is also used as an anticonvulsant it controls life-threatening seizures it is also used as pre-anesthetic medication to because of its sedative amnesic and anxiolytic effects and also as a muscle relaxant now the drugs used for anxiety disorders are load of chlordiazepucide when you are anxious you have a load of chlordiazepucide remember that lorazepam oxazepam alprazolam and diazepam and chlordiazepucide the drugs used for insomnia are phantom because when you can't sleep and you're the only one not sleeping you can see phantoms when you are hallucinating.
Fluorazepam, alprazolam, nitrazepam, temazepam, triazolam and midazolam. Let's have a look at the adverse effects of benzodiazepines. The mnemonic for the adverse effects is diazepam not pam. D for dizziness, drowsiness and disorientation.
I for impaired insomnia. A for amnesia and anorexia. Z for nothing. E for elderly specific symptoms which are hypertension and dose adjustment because it causes ambulatory impairment.
Psychomotor skill impairment. A for ataxia, amnesia and apnea. and for neonatal distress.
yeah or distress it is also called floppy baby syndrome which can be caused if the mother is taking benzodiazepines for some reason and they can be passed in the milk to the the baby. Now some important facts are that do not suggest benzodiazepines to respiratory depressed patients because it will compromise the ventilation of course and alcohol being a CNS depressant enhances the psychomotor depression of benzodiazepine and also its amnesic action. That's all about benzodiazepines.