3. Local Anesthetic Molecules
Majority of local anesthetics are tertiary amines
(except Prilocaine)
All local anesthetics are amphipathic
(lipophilic/hydrophilic)
4. 1) Lipophilic Part (aromatic ring)
2) Intermediate Chain (amide or ester)
3) Hydrophilic Part (ethyl alcohol/acetic)
5. The lipophilic part of the local anesthetic is the largest portion
of the molecule
Hydrophilic part of the local anesthetic is an amino derivative
of ethyl alcohol or acetic acid
Local anesthetics without a hydrophilic portion are not
suitable for injection but are good topical anesthetics, i.e.,
Benzocaine
6.
7. What Form Do Local Anesthetics
Exist in the Cartridge?
است ناپایدار حسی بی های دارو بیس
آور درمی نمک بصورت و کرده ترکیب اسید با آنرا جهت این بهند
است هیدروکلراید بصورت آنها نمک اغلب
دارد وجود حسی بی ماده نمک کارپول درون پس
9. pH of the interior of the nerve remains
unchanged and stable despite wide
variations in extracellular fluid pH;
so it is with the pH of the extracellular
fluid that determines the success or
failure of local anesthetics
10. Why not increase the pH of the
local anesthetic in the cartridge?
ثبات بی موضعی حسی بی داروهای بیس چونکهاست
شود جدا الکالینی محلول از است ممکن و
13. حسی بی های دارو تجزیهموضعی
pKa is a measure of a molecule’s
affinity for hydrogen ions (H+);
when the pH of a solution has the
same value as the pKa, 50% of the
drug exists as the free base (RNH+)
and 50% exists as the cation (RN)
14. Low pH (acidic) shifts toward the
cationic form; more RNH+
High pH (basic) shifts toward the
free base form; more RN
15. یونی فرم نسبی خصوصیات(RNH+, RN)دارو
دارد بستگی زیر موارد به:
pH of the local anesthetic solution
pH of the surrounding tissues
pKa of the specific local anesthetic
16.
17. higher pKa increased H+ increased Onset Time
Bupivacaine
pKa ~8.1 will take longer to work
fewer free base molecules available to penetrate the
nerve membrane
take up to 8 minutes at pH of 7.4
18. موضعی حسی بی داروهای اثر در موثر فاکتورهای
1) Diffusion of the drug through the nerve sheath
2) Binding of the drug at the receptor site in the channels
3) Free bases (RN) cross the nerve membrane
4) Cation (RNH+) blocks the receptor
19. The uncharged, lipid-soluble free base (RN)
form of the local anesthetic is responsible
for diffusion through the nerve membrane
25. Mantle Bundles (OUTSIDE)
-fasciculi that are located near the surface of the nerve
-first ones reached; exposed to higher concentration of
the solution
-blocked completely shortly after injection
-innervates more proximal regions of the nerve
(molars from IANB)
26.
27. Core Bundles (INSIDE)
-fasciculi found closer to the center of the nerve
-must delay before onset of anesthesia;
lower concentration of solution
-explains why patient may have inadequate
pulpal anesthesia in the midst of profound
soft tissue anesthesia
-innervates more distal regions of the nerve
(incisors from IANB)
28. القا زمان
هستند پزشک کنترل تحت که عواملی
1) Concentration of the drug
2) pH of the local anesthetic solution
نیستند پزشک کنترل تحت که عواملی
1) Diffusion constant of the anesthetic drug
2) Anatomical diffusion barriers of the nerve