Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++ Weak bases, hydrophilic, tertiary amines that block voltage-gated Na+ channels, preventing depolarizationSensitivity of nerve fibers to blockade: More sensitive: small diameter and lack of myelinSpinal and peripheral nerves: autonomic > sensory > motorOnset/duration of action: Unionized (uncharged) form: lipid-soluble, crosses membranesIncreased lipid solubility = decreased onset time, increased duration, increased potencyIncreased concentration and total dose =faster onsetSite of injection: more vascularized means shorter duration due to systemic uptakeNote: Epinephrine is frequently added to increase duration of blockade; however, it is unstable in alkaline conditions: Bottles containing epinephrine have an acidic pH = slower onset than when epinephrine added extemporaneouslySystemic vascular absorption (greatest to least): Intercostal nerve block > caudal > epidural > brachial plexus > sciatic–femoral > subcutaneousDivided into two groups: Amides (mnemonic: have two I's in the name): Metabolized in the liver; liver disease can increase duration and toxicityEsters: Mostly metabolized by pseudocholinesterasePseudocholinesterase deficiency severely prolongs duration; avoid in these patients ++Table Graphic Jump Location | Download (.pdf) | PrintDosage of Local Anesthetics (Also See Chapters 122 and 123)PeripheralEpiduralSpinalInfiltrationIVRAAmidesBupivacaineConcentration0.25–0.5%0.25–0.75%0.5–0.75%n/aContraindicatedDose10–40 mL5–20 mL1–3 mLn/aContraindicatedDuration4–12 h60–120 min1–3 hn/aContraindicatedOnsetSlowIntermediateRapidn/aContraindicatedLidocaineConcentration1–1.5%1.5–2%1.5–5%0.5–1%0.25–0.5%Dose10–40 mL20 mLDuration1–3 h1.5–2 h0.5–1.5 h2–8 h0.5–1 hOnsetRapidRapidRapidRapidRapidMepivacaineConcentration1–1.5%1.5–2%2–4%n/an/aDoseDuration2–4 h1–2 h1–2 hn/an/aOnsetRapidRapidRapidn/an/aRopivacaineConcentration0.5–1%0.5–1%0.5–0.75%0.2–0.5%n/aDose10–20 mLDuration5–8 h2–3 h1–3 h2–5 hn/aOnsetSlowIntermediaten/aRapidn/aEstersBenzocaineConcentrationn/an/an/aTopical: maximum 20%DoseDurationn/an/an/a0.5–1 hOnsetn/an/an/aRapidChloroprocaineConcentration2%2–3%2–3%1%DoseDuration0.5–1 h0.5–1 h1–2 h0.5–1 hOnsetRapidRapidRapidRapidCocaineConcentrationn/an/an/aTopical: 4–10%Dosen/an/a2–5 mLDurationn/an/an/a0.5–1 hOnsetn/an/an/aRapidProcaineConcentrationn/an/a2%n/aDosen/an/an/aDurationn/an/a0.5–1 hn/aOnsetn/an/aRapidn/aTetracaineConcentrationn/an/a0.5%Topical: 2%Dosen/an/a15 mgDurationn/an/a2–4 h0.5–1 hOnsetn/an/aRapidRapidPrilocaineConcentration4%n/a2%4%0.5%Dose10–15 mLn/a80 mg50 mLDurationn/an/a2–4 h0.5–1 h45–90 minOnsetRapidn/aRapidRapidRapid++Table Graphic Jump Location | Download (.pdf) | PrintMaximum Recommended Doses of Local AnestheticsMaximum recommended doseMaximum recommended dose with addition of epinephrineMedicationmg (adult)mg/kgmg (adult)mg/kgLidocaine3003–4.55006–7Mepivacaine4004.55507Bupivacaine1752–32252Levobupivacaine1502... Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth