The peripheral nervous system consists of two parts:
• afferent innervation;
• efferent innervation, which includes autonomic and somatic nervous systems.
A. DRUGS ACTING ON AFFERENT INNERVATION
1. TOPICS TO DISCUSS
1. Classifications of local anesthetics.
2. Mechanism of action of local anesthetics (LA). Influence of LA on ion currents and action potential of
nerve fibers and endings.
3. The dependence on the onset of action, duration of action and physical and chemical properties of anes-
thetics (pKa, lipophilicity), thickness and myelination of nerve fibers, discharge frequency in the nerve fibers, diffusion rate of the anesthetic to the site of administration, combination with vasoconstrictors.
4. Application for different types of anesthesia - infiltrative, conductive, topical. Anesthesia in dentistry.
5. Change of action of local anesthetics when injected into inflamed tissue.
6. Combinations of local anesthetics with vasoconstrictors (epinephrine, phenylephrine): advantages, dis-
advantages, contraindications.
7. Local and systemic (toxic) effects of local anesthetics, preventive measures
8. Astringents: tannin, zinc oxide, oak bark broth, sage leaves infusion.
9. Coating drugs: starch and flax seeds mucilages, sucralfate.
10. Adsorbents: activated charcoal.
11. Irritant drugs: mustard plasters, refined turpentine oil, menthol, ammonia solution. Background information
Local anesthetics are medications used for the purpose of temporary and reversible elimination of painful feelings in specific areas of the body by blocking transmission of nerve fiber impulses.
Local anesthetics (LAs) in nonionized (nonprotonated) form cross the axonal membrane, bind revers-ibly to a specific receptor site within the pore of the Na+-channels in nerves and block ion movement through this pore.