local anesthetics, adjuvants, and muscle relaxants

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local anesthetics, adjuvants, and muscle relaxants
2011-04-18 13:44:23
local anesthetics adjuvants

blk 4 drugs
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  1. benzocaine
    • ester-type, short acting, topical
    • blockage of voltage-dependent Na+ channels
    • SE: allergic rxns (PABA metabolite), methemoglobinemia
  2. cocaine
    • ester-type local anesthetic
    • topical anesthesia & vasoconstriction in nose, throat, oral cavity
    • blockage of voltage-dependent Na+ channels
    • blocks NE reuptake (vasoconstriction effect)
  3. lidocaine
    • amide-type local anesthetic
    • moderate duration (1-2h)
    • blocks voltage-dependent Na+ channels
    • SE: effects related to systemic absorption, mood changes, nausea, drowsiness, vision changes, headache
  4. bupivacaine
    • amide-type local anesthetic
    • oral, obstetrical surgery
    • longer duration of action (6-8h)
    • blocks voltage-dependent Na+ channels
    • SE: cardiotoxic, usually only in systemic exposure
  5. ropivacaine
    • amide local anesthetic
    • long-acting (2-6h)
    • slightly less potent, but less SE than buvivacaine
    • blocks voltage-dependent Na+ channels
  6. EMLA
    • topical anesthetic
    • Eutectic mixture of local anesthetics - lidocaine and prilocaine
    • SE: skin rxns
  7. topiramate
    • oral anticonvulsant (for epilepsy), neuropathic pain
    • modulation of Na+ channels, potentiation of GABA inhibition, blockage of glutamate, modulation of Ca++ channels
    • SE: somnolence, nausea, weight loss, numbness
  8. amitripyline
    • TCA, neuropathic pain med
    • postherpetic neuralgia, diabetic neuropathy
    • NE and 5HT reuptake inhibitor, Na+ channel blocker, NMDA antagonist
    • SE: anticholinergic effects (blurred vision, constipation, dry mouth, sedation, tachycardia, urinary retention, delirium in older pts) - worse w/tertiary form of the drug
  9. gabapentin
    • oral anticonvulsant, neuropathic pain med
    • diabetic neuropathy, postherpetic neuralgia
    • reduces current in Ca++ channel
    • highly lipid soluble, not metabolized, no SE!
  10. pregabalin
    similar to gabapentin, but more potent, greater bioavailability
  11. capsaicin
    • depletion of substance P from sensory neurons, nociceptor desensitization
    • topical analgesic, burning on initial application, low compliance
  12. Baclofen
    • central-acting w/o direct effect on skeletal muscle
    • GABA B receptors - hyperpolarization
    • SE: drowsiness, nausea/vomiting
    • withdrawal syndrome
  13. carisoprodol
    • GABA A agonist
    • central-acting
    • less frequently used
  14. cyclobenzaprine
    structurally related to TCA but not used as an antidepressant
  15. lidocaine systemic effects
    • seizures
    • cardiovascular collapse
    • death
  16. onset of nerve blockade in infected tissues
  17. mech of action of local anesthetics
    • weak bases; neutral form diffuses through PM
    • protonated form blocks Na+ channel
    • preferentially binds to more activated channels
    • small C unmyelinated fibers are affected before large A-beta fibers, higher SA
  18. amide v. ester metabolism
    • amide: hepatic metabolism, longer half-life, allergic rxns rare
    • esters: plasma cholinesterases, rapid degradation, shorter half life, PABA metabolite (allergy)