Local anaesthetics cause reversible loss of sensation in a specific part of the body. They block nerve conduction by decreasing sodium ion entry during depolarization, slowing nerve impulses. Local anaesthetics come in injectable and surface forms, with varying potencies and durations of action. They act by blocking sodium channels in resting, activated, and inactivated states. Important discoveries in local anaesthetics include cocaine in 1860 as the first agent, demonstration of anaesthetic properties in 1884, development of the first synthetic agent procaine in 1905, and discovery of lidocaine in 1948. Local anaesthetics must have low irritation, avoid permanent nerve damage, low systemic toxicity, rapid onset, and effectiveness with different routes of administration.

1. LOCAL ANAESTHETIC
By-: KARTIK TIWARI
● Outline-:

2. ★ General introduction
● Definition-: Local anaesthetic is defined as the chemical agent which causes the
reversible loss of sensation of the locally parts of the body or especially a region of the
body.
● It is used to anaesthize the special part of the body for loss the perception of the pain.
● They blocked the conduction between the neurons and block the impulse transmission.
● The characterstic of local anaesthetic are:
● It act on the peripheral nerves.
● Loss of autonomic control.
● It causes muscular paralysis.

3. Classification of local anaesthetic
● Local anaesthetic
Injectable anaesthetic Surface anaesthetic
Soluble Insoluble
Intermidiate potency
And duration
Low potency,
Short duration
High potency,
Long duration
Procaine
Chloroprocaine
Lidocaine (lognocaine)
Prilocaine
Tetracaine
Bupivacaine
Ropivacaine
Dibucaine
Cocaine
Lidocaine
Tetracaine
Proparacaine
Benzocaine
Butylamino-
benzoate
Oxethazaine

4. Procaine (protype drug)
MOA-: The local anaesthetic have
ability to block the nerve conduction
by decreasing the entry of Na+ ion
which causes decrease in
depolarization which leads to slow
conduction.
This diagram represent the three phase of the action of
the local anaesthetic agents which are:-
● Resting state
● Activated state
● Inactivated state
Resting state-: The receptors which are in normal
resting state simply it is not in activated state.
Activated state-: The activated state means enflux of
Na+ ions into pore channel.
Inativated state-: The inactivated state means not enflux
of Na+ ions into pore channel.
Mechanism of action

5. S.No. Year Scientist Discovery
1860 Nieman First Anaesthetic agent cocaine from
leaves of coca tree.
2. 1884 Karl Koller Demonstrate anaesthetic action.
3. 1905 Einhorn Develop synthetic local anaesthetic
procaine from benzoic acid and diethyl
amino ethanol.
4. 1948 Lofgren Discovered Lidocaine
HISTORY OF LOCAL ANAESTHETIC

6. PROPERTIES OF LOCAL ANAESTHETIC
1. It should not be irritating to tissues to which it is applied.
2. It should not cause any permanent alteration of nerves structure.
3. Its systemic toxicity should be low.
4. Time of onset of anaesthesia should be short.
5. It should be effective regardless of whether it is injected into the tissue or
applied locally to mucous membrane.