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29 Cards in this Set
- Front
- Back
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What transmits impulses from the periphery to the dorsal horn of the spinal cord?
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Nocioceptors
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Nocioception requires _____ stimuli.
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Noxious (pain, burn, cut... not just touch)
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What is the difference between analgesic and anesthetic?
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Analgesic - specific inhibitors of pain pathways
Anesthetic - non-specific inhibitors of peripheral sensory (pain, motor, AND autonomic) |
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Local anesthetics inhibit conduction of action potentials in ______ nerve fibers
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all afferent and efferent
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Are local anesthetics hydrophobic or hydrophillic? Weak bases or acids?
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Hydrophobic, weak bases
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What factors influence how much local anesthetic will be absorbed systemically?
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- vascularity at administration site
- drug concentration - co-administration of a vaso-constrictor - properties of medication |
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How are ester-linked local anesthetics metabolized?
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Tissue and plasma esterases (pseudocholinesterases)
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How are amide linked anesthetics metabolized?
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P450 (liver), and in lungs
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Name 3 ester-linked anesthetics.
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PTC
- procaine - tetracaine - cocaine |
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Name 4 amide-linked anesthetics.
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BLAP
- bupivicaine - lidocaine - articane - Prilocaine |
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How are ester linked and amide linked anesthetics eliminated?
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Kidney
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Describe how Local anesthetics work.
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1. Voltage gated sodium channel blocked
2. Tonic inhibiton - 3- phasic inhibition |
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Describe what tonic inhibition is
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long time between action potentials (no new pain impulse), so LA disassociates and when the next one comes, it only blocks to same effect as the previous. (only what LA can get it in the brief opening of NA channels
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Describe what voltage gated sodium blockign is.
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Block Na+ channels in neuronal membranes (open and inactivated sodium channels) - prevents propogation of new action potentials
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Describe phasic inhibition.
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As the pain action potential increases, there is less time between so LA doesn't dissociate. With each new action potential, more LA is bound and therefore it works better!
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WHat types of receptors can LA work with in addition to sodium channels?
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-K+ channels
-Ca channels -ligand gated channels -transient receptor potential channels -G-protein receptors |
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Describe the following regarding Procaine:
a) duration of action b) primary use c) metabolism d) Metabolites |
a) short acting, low hydrophobicity (low potency)
b) infiltration and dental procedures c) in plasma by plasma cholinesterases d) PABA - allergen that inhibits sulfa drugs |
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Describe the following regarding Tetracaine:
a) duration of action b) hydrophobicity c) primary use d) metabolism |
a) long acting
b) highly hydrophobic (potent!) c) spinal and topical anesthesia d) plasma cholinesterases (slowly released from tissues to blood stream) |
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Describe the following regarding Cocaine:
a) duration of action b) primary use c) metabolism d) other effects |
a) medium duration of action (medium potency)
b) ophthalmic and topical anesthesia c) d) inhibits catecholamine uptake, results in vasoconstriction and euphoria (cardiac toxicity) |
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Describe the following regarding Lidocaine and Prilocaine:
a) duration of action b) primary use c) metabolism d) Other effects |
a) medium duration, moderate potentcy
b) infiltration, nerve block, epidural, spinal, and topical anesthesia c) Liver by P450 d) prilocaine- vasoconstrictive lidocaine - antiarrhythmic (NA blocker) CNS depression, cardiotoxicity |
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Describe the following regarding Bupivicaine:
a) duration of action b) primary use c) metabolism d) Other effects |
a) long duration of action, highly potent (high hydrophobicity)
b) infiltration c) Liver by P450 d) cardiac toxicity (S-enantiomer safer - levobupivicaine) |
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What is unique about Articaine?
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partially metabolized by plasma cholinesterases, partially by p450 in the liver
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____ is used to numb an area of skin or mucosal surface via injection
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Infiltration
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Why does infiltration of local anesthetics sting?
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Kept at an acidic pH, use bicarb to help
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Topical anesthetics are absorbed ___ into the circulation
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Rapidly
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___ are injected percutaneously and may be minor or major.
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Peripheral nerve block
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____ occurs when a drug is injected near the spinal cord. Examples include ___ and ___
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Central nerve block
epidural and intrathecal anesthesia |
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A regional intravenous block is also called a ____ and is used in ____
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1. bier's block
2. arm or hand surgery |
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Describe effects of toxicity of LA on the
a) CNS b) cardiac c) PVS d) bronchial smooth muscle |
a) initial excitement then depression
b) blockage of NA, K, and Ca channels = arrhythmia c and d) initial constriction followed by dilation |
