Anxiolytic/Sedative/Hypnotics - Lichtblau Flashcards
What is the major difference between different barbiturates?
Major difference is duration of action. This will determine the best use of the drug. Classified as: Ultra-short Short-intermediate Long-Acting
In an ultra-short acting drug like thiopental the high lipid solubility allows it to distribute very quickly. What is responsible for its fast termination of action?
The redistribution to muscle/fat/etc that happens right after the drip is stopped causes termination of action.
Barbiturates have a pretty wide spectrum of action.
What is the type of problem can they do nothing for?
No barbiturate is a good anxiolytic
put you to sleep
What is the difference between pharmacokinetic and pharmacodynamic tolerance in barbiturates?
Pharmacokinetic:
- some drugs, like barbs, are inducers of drug metabolism
- repeated administration of drug will lead to lower blood concentrations
- this will decrease effect
Pharmacodynamic:
- Due to cellular adaptation
- Same drug concentration - less effect
- Primary basis for barb tolerance
What kind of problems do you need to watch out for if you have a patient on Barbs and a bunch of other meds?
Barbs are inducers of drug metabolism so other drugs are actually going to start being broken down in the liver faster
So let’s say a baby eats a bunch of phenobarbitol tablets. What are you going to do to stabilize the child?
You are going to do a sodium bicarb drip to increase the urinary pH. High urinary pH causes weak acids like Barbs to be excreted because they stay ionized and aren’t reabsorbed.
Clinical uses of barbiturates?
hypnosis
seizure control
anesthesia induction
Benzodiazepines can be used for a wide spectrum, except for:
General anesthesia
What is the brain’s master clock of circadian rhythms?
What drug will affect this part of the brain?
Suprachiasmatic Nucleus (SCN)
Ramelton is an agonist of melatonin MT1/MT2 receptors in the SCN
A sleep aid
Why do so many accidental overdoses occur in drug abusers who use barbiturates?
The things is that you develop tolerance to the psychological effects faster than you do to the anticonvulsant and lethal effect.
So basically as people abuse the drug, the therapeutic index grows very small. Soon the difference between getting high and dying can be just a couple pills…
Why do Benzos create the illusion of anesthesia?
Because they create anterograde anesthesia, so even though you are still somewhat aware, you don’t remember
What are the Benzo effects on other systems like?
Little if any effect on systems outside the CNS
Mechanism for Benzos vs Mechanism for Barbs?
Both open chloride channels to potentiate GABA’s inhibitory function (or stabilizing function) on CNS.
Benzo - increase freq of channel openings
Barb - increase duration of channel openings
Usually benzos just wear off with time, but let’s say it was important to antagonize the sedation, what drug could you use?
Mechanism?
Flumazenil (Romazicon)
-Benzo receptor antagonist
What are the non-Benzo Benzo-agonists? Name one.
What are they used for?
Any advantage to them?
- New drugs that interact with different benzo binding site subtypes on the GABA receptors
- Zolpidem (ambien)
- Used for Anxiety, insomnia, seizure, muscle relax (just like Benzos)
- Advantage: rapid onset, short duration of action, slow tolerance
