Sedative-Hypnotic Drugs Flashcards
What is a sedative vs a hypnotic drug? Shared characteristic?
Sedative - produces a calming or drowsiness (relief of anxiety)
Hypnotic - facilitates onset and maintenance of sleep
Shared characteristic: CNS depression
What are sedative-hypnotics with the highest lipid solubility often used for? Give two examples.
Rapid entrance into the CNS and thus induction agents in anesthesia
- Thiopental - rapid acting barbiturate
- Propofol - non-benzo, non-barb
What are some OTC sedative-hypnotics?
- 1st generation antihistamines
- L-tryptophan
- Melatonin, metabolite of serotonin
What terminates the action of thiopental and propofol?
Rapid redistribution of the drug from brain to peripheral tissues, and subsequent metabolism and secretion
Do sedative-hypnotics cross the placenta?
Yes! use with caution in pregnancy, as they depress neonatal vital functions
How are sedative-hypnotics typically grouped?
By duration of action, with rapid (few minutes), medium (hours), and long-acting (Days) in terms of halflife
How are benzodiazepines metabolized?
The major must first be oxidized in the liver by CYP450, and then ALL will be conjugated with glutathione and excreted in the urine
What benzos have the highest risk of excessive sedation and why?
Chlordiazepoxide, diazepam, and flurazepam
- > many active metabolites which still must be metabolized by the liver.
- > Even metabolites can bind plasma proteins, which correlates with lipid solubility and further reduces drug metabolism
What are two benzos which do not undergo liver microsomal oxidation and are directly conjugated? Why is this relevant?
- Oxazepam - think of the ox on the wall
- Lorazepam
-> safe to give in patients with impaired liver function
What are the three main hypnotics and why are they short-acting?
They are rapidly metabolized by the liver
- Zolpidem
- Zaleplon
- EsZopiclone
(3 Z’s for sleep)!
How do benzodiazepines work? How does this change GABA’s pharmacodynamic parameters?
Bind an allosteric site on GABA-A and increase the frequency / probability of GABA-mediated chloride channel opening (binding GABA does not always cause it to open)
Increases POTENCY of GABA (less GABA required to get the same response)
How do barbiturates work? How does this change GABA’s pharmacodynamic parameters? What other drug falls into this class?
Bind an allosteric site on GABA-A and increases the duration of GABA-mediated choride channel opening (higher efficacy, but no change in potency)
Propofol (similar in use to thiopental) has the same mechanism, but is a non-benzo, non-barb
How do we know that the “3 Z” hypnotics bind the same allosteric site as benzodiazepines, despite being non-benzodiazepines?
CNS depressant effects are antagonized by the benzodiazepine receptor antagonist “flumazenil” - fluffy the dog
What drug is a partial agonist of 5-HT1A receptors and what is its primary indication? How long is its effect?
Buspirone
Takes weeks to manifest the effects -> used for long-term anxiety treatment, especially generalized anxiety disorder of patients with substance abuse (not dangerous like benzos)
Does Buspirone interact with benzodiazepines?
No, it has no cross-reactivity with any GABA-mediated drugs. It is not even a CNS depressant, just an anxiolytic Therefore, if discontinuing a benzo for it, benzo should be tapered
What is the melatonin receptor agonist approved for sleep onset insomnia? Is it good for sleep maintenance? Does it or buspirone have abuse potential?
Ramelteon (“melt way” in Sketchy)
Only good for falling asleep
No abuse potential for either
What are the adverse effects of ramelteon?
Increased serum prolactin, decreased serum testosterone, and doing things while asleep
What is one drug which can be used for both sleep onset and sleep maintenance insomnia? Does it have abuse potential? What are its side effects?
Suvorexant -> orexin receptor antagonist
- > no abuse potential
- > daytime drowsiness and suicidal ideation