2. Local Anesthetic
• Drugs that cause reversible loss of
sensory perception specially of pain in a
restricted area of the body, when applied
topically or local injection.
If applied to a mixed nerve, sensory and
motor impulses are interrupted resulting
in muscular paralysis and loss of
autonomic control.
2
6. 14
BASED ON DURATION OFACTION
• 2% lignocane without vasoconstrictorUltraShort Duration
• Procaine,
• 2 % Lignocaine
Short duration
• Articaine
• Mepivacaine
• Prilocaine
Intermediate
duration
• Bupivacaine (400-450 min)
• EtidocaineLong duration
7. BAS E D O N O R I GI N
• cocaineNATURAL
• Amino esters of PABA- procaine
• Alkyl esters of PAB A- benzocaine
• Amino esters of MABA- unacaine
• Amino amides- xylocaine ,
bupivacaine
SYNTHETIC
NITROGENOUS
COMPOUND
• benzyl alcohol
SYNTHETIC NON
NITROGENOUS
COMPOUND
MISCLLANEOUS DRUGS - Clove Oil,Phenol
7
8. • Diffusion of the base (nonionized) form across the nerve sheath
and nerve membrane
• Re-equilibration between the base and cationic forms inthe
axoplasm
• Penetration of the cation into and attachment to areceptor site
within the sodiumchannel.
• Blockade of the sodium channel
• Inhibition ofsodium conduction
8
SEQUENCE OF EVENTS WHICH RESULT IN
CONDUCTION BLOCKADE
9. SEQUENCE OF EVENTS WHICH RESULT IN
CONDUCTION BLOCKADE
• Decrease in the rate and degree of the
depolarization phase of the action potential
• Failure to achieve the threshold potential
• Lack of development of apropagated action
potential
• Blockade of impulseconduction
9
12. Pharmacokinetic
12
Esters:
• These include cocaine, procaine, tetracaine, and
chloroprocaine.
• Short duration
They are hydrolyzed in plasma by pseudo-
cholinesterase. One of the by-products of metabolism is
PABA - the common cause of allergic reactions seen with
these agents and also antagonize the action of
sulfonamides.
• Rarely used for infiltration or nerve block, but are still
used topically on mucus membranes
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Amides:
• These include lidocaine, mepivacaine, prilocaine,
bupivacaine, and etidocaine.
• Produce more intense and longer lasting anesthesia
• Bind to α1acid glycoprotein in plasma
• They are metabolized in the liver to inactive agents.
True allergic reactions are rare (especially with
lidocaine)
Pharmacokinetic
14. 14
Types of Local Anesthesia
Infiltration Anesthesia:
Local infiltration occurs when the nerve endings in the skin
and subcutaneous tissues are blocked by direct contact with
a local anesthetic, which is injected into the tissue.
Local infiltration is used primarily for surgical
procedures involving a small area of tissue (for example,
suturing a cut).
15. 15
This type of anesthesia is accomplished by the application of a
local anesthetic to skin or mucous membranes.
Surface anesthesia is used to relieve itching, burning, and
surface pain.
This technique is often used during examination procedures
involving the respiratory tract.
The topical block easily anesthetizes the surface of the cornea
and the oral mucosa.
Surface Anesthesia:
16. 16
Conduction block anaesthesia:
Two types
1. Field block:- LA is injected subcutaneously in the surrounding area of the
nerves. So that all other nerves coming to a particular field are blocked.
e.g. scalp and anterior abdominal walls
2. Nerve block:- LA injected around the anatomically localized nerve
trunk. The block is usually described by adding the nerve name.
e.g. radial nerve block, ulnar nerve block.
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Epidural Anesthesia
This type of anesthesia is accomplished by injecting
a local anesthetic into the epidural space.
Widely used to provide analgesia or anesthesia in
surgical and obstetric practice.
Spinal block Anesthesia:
In spinal anesthesia, the local anesthetic is injected into the
subarachnoid space of the spinal cord
Also referred as subarachnoid or intrathecal block anesthesia or
spinal anesthesia.
Site- subarachnoid space between L2-L3 or L3-L4
Used to anesthetise lower abdomen, hind limbs.
18. PROCAINE (NOVOCAINE)
18
•First synthetic injectable localanesthetic.
•Produce the greatest vasodilation of all currently used local
anesthetics.
•Slower clinical onset (6-10mins.)
•Used for
• Soft tissue anesthesia for15-30 mins.
•Systemic toxicity negligible because rapidly destroyed
in plasma
•Max. recommended dose for peripheral nerve block
1000mg
19. Barbiturates &
Benzodiazepines MOA:
1) Both bind to GABAA
receptors, at differentsites
•Both cause increase Cl-
influx in presence of GABA
•BNZ binding can be
blocked by flumazenil.
2) Barbs at high doses - are
also GABA mimetic, block
Na channels
NMDA/glutamate Rs
20. LIDOCAINE
•The most popular contains
epinephrine 1:100,000 and provides
good anesthesia for healthy
patients.
•Lidocaine with epinephrine
1:50,000 is used for hemostasis,
but because of the rebound
effect noted earlier, itshould be
used sparingly.
1:200000 conc. is safest
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As well as potent
21. Lignocaine ( Xylocaine)
•Most widely usedAmide linked LAand most
versatile ana.
•Has variety of applications like Local, nerve block,
topical.
•When used locally action starts within 3mts,
more profound anesthesia, has longer duration
of action and greater potency.
•Overdose causes muscle twitchings, convulsions,
cardiac arrhythmias, fall in BP,coma, respiratory
arrest.
•Most popular anti arrhythmicdrug
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