Term
| What are the two numbers that matter in inhaled anesthetics? |
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Definition
-MAC (minimal alveolar anesthetic concentration); basically ED50, but as a percentage
-Has to do with lipid solubility
-Blood-Gas ratio; is actually the bound/free gas ratio
-Lower values mean faster onset & recovery
-Has to do with blood solubility |
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Term
| Give the major inhaled anesthetics? |
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Definition
-Nitrous oxide; MAC = 104%, B-GR = 0.5 (fast, but weak)
-Spontaneous abortion, diffusional hypoxia, no metabolism
Halothane & "-furanes "; MAC = 0.8%, B-GR = 2.3 (slow, but very strong)
-Malignant hyperthermia, liver damage, arrhythmias (from catecholamine sensitization) |
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Term
| List the intravenous anesthetics? |
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Definition
-Thiopental (a barbiturate)
-Midazolam (a benzodiazepine)
-Propofol
-Fentanyl (an opiate)
-Ketamine
-See 151 for memory tools and specific info |
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Term
| What is the mechanism of action of local anesthetics? |
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Definition
1. Non-ionized form goes into nerve terminal (RNH2)
-Usually inject with basic solution to help this (carbonated)
2. Ionized form inside cell is the active form
-Slightly acidic in cells
3. Binds to inactivated sodium channel and blocks it |
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Term
| What are the two kinds of local anesthetics? |
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Definition
-Esters; procaine, cocaine, benzocaine (all have one "i")
-Amides; lidocaine, bupivacaine, mepivacaine (two "i"s)
-All of them have "-caine" |
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Term
| What nerve types do local anesthetics effect more? |
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Definition
-Lower diameter fibers more (easier to enter)
-Dull pain is unmyelinated C fibers
-Sharp pain is lightly myelinated A-delta fibers |
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Term
| What do we administer with local anesthetics? What drug do we not need this for? |
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Definition
-α1 agonist are given to vasoconstrictor prolongation of effect and avoidance of toxicity from going systemic
-Otherwise would be neurotoxic and cardiotoxic
-Cocaine inhibits NE uptake, and so indirectly stimulates α1 receptors without need of coadministration of α1 agonist
-Used as topical gel |
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Term
| What about allergies and local anesthetics? |
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Definition
-They are metabolized to PABA, which commonly causes allergic reactions in skin (para amino benzoic acid)
-Side note; sulfonamides are an antimicrobial class of drugs that also give PABA and have sulfur (big for allergies) |
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Term
| What are some naturally occurring toxins that act like local anesthetics? |
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Definition
-**Tetrodotoxin; from puffer fish (Fugu fish)
-Saxitoxin; from red tide algae
-Ciguatoxin; exotic fish
-Batrachotoxin; frogs
-All of them act on the voltage dependent Na+ channels |
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Term
| Where does ACh usually bind on skeletal muscle receptors? How many blockers to shut them off? |
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Definition
-Nm receptors bind two ACh at two **α subunits in order to be activated?
-We only need one blocker per receptor, however |
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Term
| What are the two kinds of muscle relaxants? Antidote? |
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Definition
-Nondepolarizing (competitive); "-curium" family
-Can reverse with AChE inhibitors-->*neostigmine
-Depolarizing (noncompetitive); succinylcholine |
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Term
| What are the two major nondepolarizing skeletal muscle relaxants and attributes? |
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Definition
Atracurium
-*Safe for liver and kidney because it is not metabolized
-Spontaneously becomes *laudanosine, which may cause *seizures (Hoffman degradation)
Mivacurium
-Metabolized by an **esterase (fast & slow metabolizers)
-Usually *short duration, but not if slow metabolizer |
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Term
| What is the depolarizing muscle relaxant and how does it act? Cautions (3)? |
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Definition
-Succinylcholine is a nonreversible agonist that essentially puts them into cholinergic crisis, eventually causing *flaccid paralysis
-No antidote, but quickly metabolized by pseudocholinESTERASE*
-Have to worry about *slow metabolizers
-Hyperkalemia; lengthens hyperpolarization
-Malignant hyperthermia (from extreme muscle rigidity) |
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Term
| What does extreme muscle rigidity cause? Who is at risk? How do we treat? What are three drug types that can cause it? |
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Definition
-Causes acidosis and hyperthermia (just like exercise)-->SANS response-->inc. HR/arrhythmia & BP [called **malignant hyperthermia**]
-**Ryanodine receptor mutations are usually seen
-**Dantrolene to treat (Dan needs to relax about Ryan); blocks Ca++ release for sarcoplasmic reticulum
1. Inhaled anesthetics
2. Skeletal muscle relaxants
3. Antipsychotics (in neuroleptic malignant syndrome) |
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Term
| What are two centrally acting muscle relaxants and what do they bind? Used for? |
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Definition
-Benzodiazepines (binds GABA-A receptors)
-Baclofen (binds GABA-B receptors)
-Used for spasticity |
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