Module 6: Pharmacology of Local Anesthetic

profound anesthesia

onset and duration

agent

technique

general factors

concentration

diffusion to site

lipid solubility

protein binding

block: longer duration

infiltration: faster onset

PROS: faster onset, simple, safe, good hemostasis w vasoconstrictor

CONS: multiple injections for multiple teeth, shorter duration of anesthesia

anesthetics

general characteristics

types

lidocaine

mepivacaine

prilocaine

articaine

bupivacaine

vasoconstrictor presence

physiology of anesthetics

size :overall diameter of the nerve bundle

lipid : amount of myelin sheath

Central Core Theory : peripheral fibers anesthetized first; proximal first = molars; central fibers to most distal = incisors

anesthetic volume, tissue space and density critical length = 3 nodes minimum/ 5 mm

infiltrations : 1/2 to 3/4 cartridge

IA nerve block: 3/4-1 is ideal

delayed or failed onset

disassociation rate: BH+ must disasociate to unionized base form to pass through nerve membrane

transport/perfusion rate : rate of passage through membrane

reassociation rate : needs to reassociate to bind

binding rate: rate of actual binding to membrane/sodium gated ion channels

reasons for anesthetic failures

anatomical/physiological variations

technical errors of administration

patient anxiety

inflammation and infection

defective/expired solutions

decreased tissue pH --> decreased disassociation of BH+ to B

hybrid anesthetic; good for pt with liver problems

troubleshooting

  1. block injection
  1. PDL/intraosseous injection OR Buccal/Lingual infiltration w articaine/prilocaine

amides

2% plain : plural anesthesia 5-10min; soft tissue 1-2 hours

2% w/ 1:100k or 1:50k : pupal anesthesia 1-2 hours, soft tissue 3-5 hours

xylocaine, octocaine, lignospan

3% plain : plural anesthesia 20-40 min, soft tissue 2-3 hours

2% w/ 20k levonordefrin : plural 1-1.5 hours, soft tissue 3-5 hours

4% plain = citanest; plural 40-60 min, soft tissue 2-3

4% 1:200k epi = citanest forte: pulpal 1-1.5 hours; soft tissue anesthesia 3-8 hours

4% 1:100k -1:200k epi: pulpal anesthesia 1-1.5 hours, soft tissue 2-4 hours

0.5% with 1:200k long-acting by block injection, plural anesthesia 1.5-4 hours, up to 7 hours; soft tissue anesthesia 5-12 hours

good for short procedures <1 hour as infiltrate or block

short procedures <1 hour as a block

as a block, > 2 hour or post-op analgesia

for difficult patients (w/ vasoconstrictor)

contraindications

relative

absolute

patients on tricyclic antidepressants

unstable angina

myocardial infarction < 6 mo

coronary artery bypass surgery <3 mo

refractory arrhythmia

untreated/uncontrolled HTN

untreated or uncontrolled congestive heart disease

uncontrolled diabetes or other endocrine diseases

phenothiazine antipsychotics

nonselective beta blockers

recreational drugs or ADD/ADHD meds