Module 3 - CNS Depressant Agents Flashcards
CNS depression
continuum ranging from relaxation, to sedation, to the induction of sleep and anesthesia
CNS depressants uses
anesthesia and to treat anxiety, sleep and seizure disorders
CNS classes
Barbiturates
Benzodiazepines
Miscellaneous drugs
sedatives
inhibit CNS to Reduce nervousness, excitability, irritability without causing sleep
hypnotics
calm and sooth CNS causing sleep
-sedatives administered in high doses become hypnotics
sedative-hypnotic
- At low doses, calm or soothe the CNS without inducing sleep
- At high doses, calm or soothe the CNS to the point of causing sleep
what does the limbic system control?
emotions
reticular activation system
processes that trigger anxiety, restlessness, sleep
hypothalmus regulates
homeostasis
what is the job of reticular formation
sends info to hypothalmus
Gamma-Aminobutyric Acid (Gaba)
- anti-anxiety neurotransmitter produced by glutamate
- decreased levels cause brain nerves to be overactive and transmit quickly
- sensitive fight or flight (need sm GABA to initiate normally)
- characterized by nervousness, mental strain, fear, worry and a variety of anxiety disorders
insomnia includes
Difficulty falling asleep
Staying asleep
Non-restorative sleep
In combination with daytime dysfunction or distress
insomnia associated with
anxiety
short term - stress
certain foods/ drinks
consequences of insomnia
depression, manic disorders, chronic pain
rebound insomnia
caused by discontinuation of long term use of sedatives without weening off
Barbiturates
hypnotic, sedative, anticonvulsant, anesthesia for surgical procedures
- narrow therepeutic index
- not used very often
barbiturate uses
Used for reoxidation and uncontrollable seizures put people into barbiturates coma until enough seizure drugs are in blood and then take out of coma
issues with barbituates
Increases metabolism of other drugs, affects liver
High chance of abuse and addiction
Suppress
Affects the heart
barbituates
category: Ultrashort
route, onset and duration
route - IV
onset - less than 15 mins
duration - 2 hours
example - methohexital, thiamylal, thiopental
barbituates
category: short
route, onset and duration
route- PO
onset - 15-20 min
duration - 2-4 hours
examples- pentobarbital, secobarbital
barbituates
category: Intermediate
route, onset and duration
route - PO
onset - 20-30 min
duration - 2-4 hours
example - butabarbital
barbituates
category: long
route, onset and duration
route - PO
onset - 30-60 min
duration - 6-8 hours
example - phenobarbital, mephobarbital
barbituates
mechanism of action
Site of action
-Inhibits brain impulses from passing through limbic and reticular activating systems (brain stem)
- Bind to GABA receptor-chloride channel molecule
- By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited
barbituates
effects
-Low doses: sedative effects
-High doses: hypnotic effects and lowers respiratory rate
-Notorious enzyme inducers
Stimulate liver enzymes that cause the metabolism or breakdown of many drugs
Overdose: respiratory depression to arrest; CNS depression (sleep to coma to death)
Can be therapeutic (e.g., anesthesia induction; uncontrollable seizures)
barbituates
side effects on nervous system
nervous system: Drowsiness, lethargy, vertigo, mental depression, coma
barbituates
side effects on cardio vascular system
Vasodilatation and hypotension, especially if given to fast
barbituates
side effects on respiratory
Respiratory depression, apnea, bronchospasms, cough
barbituates
side effects on GI
nausea/vomiting, diarrhea, constipation
barbiturate side effects on Hematology
Agranulocytosis, thrombocytopenia, megaloblastic anemia
barbiturate
general side effects
Hypersensitivity reactions (rash, fever, urticaria, etc.) **Reduced REM sleep resulting in agitation and inability to deal with normal stress
barbiturate
drug interactions
Additive effects
-ETOH, antihistamines, benzodiazepines, narcotics, tranquilizers
Inhibited metabolism
-MAOIs will prolong effects
Increased metabolism
-Reduces anticoagulant response, leading to possible clot formation
Benzodiazepines
sedative-hypnotic or anxiolytic
- used for short-term treatment of insomnia caused by anxiety (sedative-hypnotic)
- safe but can still cause tolerance
Benzodiazepines
Indications
sedation, sleep induction, skeletal muscle relaxation, anxiety relief, treatment of alcohol withdrawal, agitation, depression, epilepsy, balanced anesthesia
what is the problem with benzodiazepines with high potency and short 1/2 life
moe likely to lead to problems with dependence
ex) lorazepam, oxazepam and loprazolam
what is the problem with benzodiazepines with long 1/2 life
residual effects into the following day (feel hungover)
ex) withdrawal less likely
what type of benzodiazepine has the least issues
intermediate
benzodiazepine
mechanism of action
- Depress CNS activity
- Affect hypothalamic, thalamic, and limbic systems of the brain
- Benzodiazepine receptors
- Do not suppress REM sleep as much as barbiturates do
- Do not increase metabolism of other drugs
benzodiazepines
drug effects
- Calming effect on the CNS
- Useful in controlling agitation and anxiety
- Reduce excessive sensory stimulation, inducing sleep
- Induce skeletal muscle relaxation
benzodiazepines
side effects
*Mild and infrequent Headache Drowsiness Dizziness Vertigo Lethargy Paradoxical excitement (nervousness) “Hangover effect”
benzodiazepine antidote
flumazenil
*has a short half-life - must administer more than once
when are benzodiazepines dangerous?
when taken with other sedatives or alcohol
what are miscellaneous CNS depressants?
not benzodiazepines or barbiturates
-treat social anxiety disorder
must use CNS depressants cautiously in….
the elderly
Those with suicidal potential
Those with impaired renal or liver function
pts
