Test 2 Flashcards
What do vasoconstrictors oppose in local anesthetics?
Oppose rapid uptake
Specific protein receptor theory
The binding of local anesthetic molecules to structural proteins known as specific protein receptor sites. Temporarily transform nerve membranes to nonexcitability.
2 primary routes of delivery
Topical
Submucosal injection
Topical route of delivery
Effective on mucosa due to ease of penetration through mucosal barriers
Submucosal injections route of delivery
Allows for direct placement of drug close to nerves
Desirable properties of local anesthetics (3)
Biocompatibility, safety and efficacy, and pKa and pH.
Biocompatibility
Nonirritable, nontoxic to tissues, nonallergenic, biotransformable, completely reversible, no systemic effects
Safety and efficacy
Effective in tissues and mucous membranes, rapid onsets and no residual effects, therapeutic durations, adequate potency, sterilizable, patient remains conscious.
pKa and pH
Relevance of pKa (the dissociation constant) and pH. When pKa=pH, there is an equal distribution of cations and unchanged base molecules in solution
Clinical application of pKa
Local anesthetics have pKa range from 7.7-8.1. Determine onset of local anesthetics
Primary benefit of local anesthetic
Suppression of pain sensations without significant central nervous system depression. Allows for the majority of dental procedures to be performed under local anesthesia without exposing patients to the risks of general anesthesia
Biotransformation
Metabolism of local anesthetic drugs, reduces or eliminates their toxicity. Breaks down the drug into its components called metabolites. Process occurs primarily through one of two pathways, the liver or in the blood.
Liver pathway
Hepatic p450 isoenzyme system
Metabolism in the blood is by what?
Pseudocholinesterase
What is an enzyme responsible for
Breaking down esters
Biotransformation of amides
Amides are bupivscaine, lidocaie, and mepivacaine.
In the liver by hepatic p450 isoenzymic system. In addition to the liver, prilocaine is biotransformed in the kidneys and lungs with very little excreted unchanged
Biotransformation of esters
Esters include benzo cane, procaine, tetracaine. Biotransformed in the blood by pseudochlorinesterase
Elimination half-life
The rate at which a drug is removed from the system execution. The time necessary to metabolize and secrete 50% of a drug. Shorter half-life drugs may be readministered sooner with less risk of overdose. Consideration should be made with nursing mothers. Articaine has the shortest half-life of all amides
Shortest to longest half-life of amides
Articaine equals .75 hours. Prilocaine equals 1.6 hours. Lidocaine equals 1.6 hours. Mepivacaine equals 1.9 hours Bupivicaine equals 3.5 hours
Nasopalatine landmark
Incisive foramen
Risks for nasopalatine
Minimal risk. Post op pain injection. Hematoma rarely. Postop edema
Indication for nasopalatine
Palatal soft and osseous tissue in the anterior third of the palate: canine to canine
Landmarks for palatal anterior superior alveolar
Nasal Palantine canal in the incisive papilla
Risks for the palatal anterior superior alveolar
Risk is minimal. Postop pain injection site. Hematoma rarely. Post op edema. Risk of necrosis with use of epi-