Neuro - sedatives Flashcards
Barbiturates
Phenobarbital; Pentobarbital; Thiopental; Secobarbital
MOA of barbiturates
Facilitate GABA-A action by increasing duration of chloride channel opening; thus decreasing neuron firing; Contraindicated in porphyria; Used as a sedative for anxiety; seizures; insomnia; and induction of anesthesia (thiopental)
Side effects of barbiturates
Respiratory and cardiovascular depression (can be fatal); CNS depression (can be exacerbated by EtOH use); Dependence; Drug interactions (induces cytochrome P-450); Overdose treatment is supportive (assist respiration and maintain BP)
Benzodiazepines
Diazepam; Lorazepam; Triazolam Temazepam Oxazepam Midazolam Chlordiazepoxide Alprazolam
MOA of benzodiazepines
Facilitate GABA-A action by increasing frequency of chloride channel opening; Decrease REM sleep; Most have long half lives and active metabolites; Exceptions - triazolam; oxazepam; and midazolam are short acting - higher addictive potential; Used in anxiety; spasticity; status elipticus (lorazepam and diazepam); detoxification (especially alcohol withdrawal-DTs); night terrors; sleepwalking; general anesthetic (amnesia; muscle relaxation); hypnotic (insomnia)
Side effects of benzodiazepines
Dependence; Additive CNS depression effects with alcohol; Less risk of respiratory depression and coma than with barbiturates; Treat overdose with flumazenil (competitive antagonist at GABA benzodiazepine receptor)
ZolpidemZaleplonEszopiclone
Nonbenzodiazepine hypnoticsAct via the BZ1 subtype of the GABA receptorEffects reversed by flumazenilUsed to treat insomnia
Side effects of zolpidem; zaleplon; and eszopiclone
Ataxia; headaches; confusionShort duration because of rapid metabolism by liver enzymesUnlike older sedative-hypnotics; cause only modest day-after psychomotor depression and few amnestic effectsDecreased dependence risk than benzodiazepines
Inhaled anesthetics
HalothaneEnfluraneIsofluraneSevofluraneMethoxyflurane**Nitrous Oxide
Effects of inhaled anesthetics
Myocardial depressionRespiratory depressionNausea/emesisIncreased cerebral blood flow**Decreased cerebral metabolic demand
Side effects of halothane
Hepatotoxicity
Side effects of methoxyflurane
Nephrotoxicity
Side effects of enflurane
Proconvulsant
Side effects of nitrous oxide
Expansion of trapped gas in a body cavity
Malignant Hyperthermia
Rare; life-threatening hereditary condition in which inhaled anesthetics (except nitrous oxide) and succinylcholine induce fever and severe muscle contractions Treatment is dantrolene.
Nitrous Oxide
Inhaled anesthetic Low blood solubility; Low lipid solubility; Low blood solubility provides rapid induction and recovery time; Low lipid solubility means it has low potency
Halothane
Inhaled anesthetic; High blood solubility; High lipid solubility; High lipid solubility means it is highly potent; High blood solubility means there is slow induction and recovery
Thiopental
Intravenous Anesthetic - Barbiturate; High potency; high lipid solubility; rapid entry into brain; Used for induction of anesthesia and short surgical procedures; Effect terminated by rapid redistribution into tissue and fat; Decreases cerebral blood flow
Midazolam
Intravenous Anesthetic - Benzodiazepine; Most common drug used for endoscopy; Used adjunctively with gaseous anesthetics and narcotics; May cause severe postoperative respiratory depression; decrease in BP; and anterograde amnesia; Treat overdose with flumazenil
Ketamine
Intravenous Anesthetic - Arylcyclohexylamines; PCP analog that acts as dissociative anesthetic; Blocks NMDA receptors; Cardiovascular stimulant; Causes disorientation; hallucination; and bad dreams; Increases cerebral blood flow
Morphine and fentanyl
Opiods used with other CNS depressants during general anesthesia
Propofol
Intravenous anesthetic; Used for sedation in the ICU; rapid anesthesia induction; and short procedures.; Less postoperative nausea than thiopental; Potentiates GABA-A
Esters - local anesthetics
Procaine; Cocaine; Tetracaine
Amides - local anesthetics
Lidocaine; Mepivacaine; Bupivacaine
MOA of local anesthetics
Block sodium channels by binding to specific receptors on the inner portion of the channel;Preferentially bind to activated sodium channels; so most effective in rapidly firing neurons;Tertiary amine local anesthetics penetrate membrane in uncharged form; then bind to ion channels as charged form
Side effects of local anesthetics
CNS excitation; Severe cardiovascular toxicity (bupivacaine); Hypertension; Hypotension; Arrhythmias (cocaine)
Succinylcholine
Depolarizing Neuromuscular Blocking Drug; Strong ACh receptor agonist - produces sustained depolarization and prevents muscle contraction; Reversal of blockade: Phase I (prolonged depolarization) - no antidote - block potentiated by cholinesterase inhibitors. Phase II (repolarized but blocked; ACh receptors are available; but desensitized) - antidote consists of cholinesterase inhibitors
Side effects of succinylcholine
*Complications include: Hypercalcemia + Hyperkalemia; Malignant Hypertension
Nondepolarizing neuromuscular blockers
Tubocurarine; atracurium; mivacurium; pancuronium; vecuronium; rocuronium; Competitive antagonists - compete for ACh for receptors; Reversal of blockade - neostigmine; edrophonium; and other cholinesterase inhibitors
Neostigmine
Cholinesterase Inhibitor; Used to reverse neuromuscular blockade with nondepolarizing blockers; Must be given with atropine to prevent muscarinic effects such as bradycardia
Dantrolene
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle; Used to treat malignant hyperthermia and neuroleptic malignant syndrome (a toxicity of antipsychotic drugs)
