Section 4: CNS Flashcards
BZ mech
Act through BZ receptors, an allosteric site in the GABA-A complex in the CNS.
Increase FREQUENCY of Cl- channel opening (FREnzodiazepines vs barbiDURates), cause membrane hyperpolarization.
BZ1 receptor mediates sedation, BZ2 mediates anti-anxiety & cognitive impairment.
Aprazolam
Class: BZ
Use: Anxiety, panic, phobias
“-olam” suffix -> short acting
Diazepam
Class: BZ
Use: Anxiety, pre-op sedation, muscle relaxation, withdrawal states
Long acting
Lorazepam
Class: BZ
Use: Anxiety, pre-op sedation, status epilepticus (IV)
Midazolam
Class: BZ
Use: Pre-op sedation, anesthesia (IV)
“-olam” suffix -> short acting
Temazepam
Class: BZ
Use: Sleep disorders
Oxazepam
Class: BZ
Use: Sleep disorders, anxiety
Short acting.
Treatment and symptoms of alcohol withdrawl (with timeline)
Treatment: long-acting BZs (diazepam, chlordiazepoxide)
8-12 hours: tremulousness, insomnia, anxiety, autonomic instability
12-24 hours: seizures
48-96 hours: delerium tremens (fever, disorientation, severe agitation)
Name the short acting BZs
“-olam’s” Midazolam, Alprazolam
and Oxazepam
Name the long acting BZs, and why they’re long acting
Diazepam, Chlordiazepam
All BZs metabolized by the liver. These
BZ side effects, contraindications, and withdrawal sx
Addiction (more connon in short-acting), somnolence, confusion, disorientation, ataxia
Containdications: old age, other CNS depressants (1st gen anti-H, alcohol, barbs, neuroleptics)
Withdrawal: rebound insomnia, anxiety, seizures if used as antiepileptic or in high doses (similar to alcohol withdrawal
All BZ uses
Panic disorder (BZs are second line to SSRIs)
GAD (BZs are second line to SNRIs)
Alcohol withdrawl
UMN spasticity
Consious sedation for minor procedures
General anesthesia and anterograde amnesia
Parasomnias in children (sleepwalking, night terrors)
Status epilepticus (BZs are 1st line for acute; phenytoin for prophylaxis)
Flumazenil
Competitive antagonist at the BZ receptor, reverses BZ sedation but precipitates S/E like seizures
Barbiturate mech
Binds to allosteric site in the GABA-A complex in the CNS.
Increase DURATION of Cl- channel opening (FREnzodiazepines vs barbiDURates), cause membrane hyperpolarization.
Barbiturate uses
Essential tremor (1st line, along w/ propranolol), seizures (phenobarbital, IV), induction of anesthesia (thiopental, IV)
Barbiturate side effects
Hypotension, cardio/resp. depression, CNS depression (coma, avoid in elderly), addiction
Potent CYP450 induction
Thiopental
Short acting barbiturate, used IV for induction of anesthesia
Phenobarbital
Barbiturate, used IV for seizures
Barbiturate distribution and redistribution
Rapidly accumulate in the brain and rapidly redistribute in the tissues (muscle and fat) leading to quick onset and duration of anesthesia
Zolpidem, Zaleplon, esZopiclone class and mech
Class: non-BZ hypnotics
Mech: Binds to the SAME allosteric site in the GABA-A complex as BZs (BZ1 site)
(Alcohol and Barbiturates each have their own site)
Zolpidem, Zaleplon, esZopiclone antidote
Flumazenil (same as BZs, can still precipitate seizures)
Zolpidem, Zaleplon, esZopiclone use:
Sleep-onset insomnia. Zolpidem and Zaleplon are rapidly metabolized by the liver. Fast onset, short half-life. Eszopiclone has the longest half-life and can be used for sleep maintenance too
Zolpidem, Zaleplon, esZopiclone side effects
Less likely to cause tolerance/addiction compared to BZs
Still contraindicated in elderly and with other CNS depressants (1st gen anti-H, EtOH, BZs, barbs), can cause delirium/cognitive impairent
Ramelteon
Class: Melatonin agonist
Use: Insomnia
Mech: maintaings circadian rhythm in the SCN of the hypothalamus
Fomepizol
Class: Alcohol dehydrogenase inhibitor
Use: ethylene glycol, methanol, ethanol poisoning
Prevents ethylene glycol-> glycolaldehyde-> glycolic acid-> oxalic acid
Prevents methanol-> formaldehyde -> formic acid
