CNS Sedative-Hypnotic Drugs - Ch. 37 Flashcards
What are sedatives?
Drugs that have an inhibitory effect on the CNS to the degree that they reduce nervousness, excitability and irritability without causing sleep
What are hypnotics?
Reduce CNS function to the point that they cause sleep
-sedative can become a hypnotic if given in large enough doses (sedative-hypnotics)
What are the kinds of sedative-hypnotics?
Benzodiazepines (more commonly used)
Barbiturates
What are barbiturates used for?
Rarely as sedative-hypnotic
Antiepileptic
Anaesthesia for short surgery
Example of short acting barbiturates?
Pentobarbital
Example of long acting barbiturates?
Phenobarbital
-antiepileptic
What kind of therapeutic index do barbiturates have?
Narrow therapeutic index
-need to be monitored
What is mechanism of action barbiturates?
Broad CNS depression action
Potentiates GABA action and mimics GABA
Where are barbiturates metabolised and excreted?
Metabolised by Liver
Excreted in urine
What does barbiturate overdose lead to?
Respiratory depression, respiratory arrest
CNS depression: sleep to coma, death
Why is there a reduced clinical use of barbiturates?
Tolerance
Physical dependence
Live enzyme induction
Abuse potential
powerful respiratory depressants
no antidote
What is the most-frequently prescribed sedative-hypnotic?
Benzodiazepines
Examples of long acting benzodiazepines?
chlordiazepoxide, clorazepate, flurazepam
Examples of intermediate acting benzodiazepines?
Lorazepam (Ativan)
oxazepam
Examples of short-acting benzodiazepams?
IV Midazolam (Versed)
Triazolam
(conscious sedation)
What is the mechanism of action of benzodiazepines?
Enhance seefyet of GABA
decerases neuronal excitability –> decreased CNS activity
Benzodiazepines do not suppress what as much as barbiturates?
REM sleep
Benzodiazepines do not increase what of other drugs?
Metabolism
What kind of benzodiazepines administration does not depress respiration excessively?
PO
What are benzodiazepines used for inducing sleep short term?
Insonnia due to anxiety
-reduces excessive sensory stimulation
What may occur after a 3-4 week regimen of benzodiazepines has been discontinued?
Rebound insomnia
What other hypnotics are used for short-term management of insomnia?
BZD-like drugs
Zolpidem (ambien)
Zaleplon
Zopiclone