This ppt provides notes of chapter Local Anaesthetic for d.pharmay students

1. 2. DRUGS ACTING ON CNS
J) LOCAL ANAESTHETICS
Prepared by – Mr. Digambar Jadhav ( M.Pharm)
HOD
Padmini College of Pharmacy,
Dighanchi.

2.  LOCAL ANAESTHETICS :
 Defination : “ Local anaesthetics are the pharmacological
agents which when applied or injected, block conduction as
well as generation of impulse in localized area and bring
loss of sensation without affecting degree of
consciousness.”

3.  CLASSIFICATION :
1. Naturally occurring : Cocaine
2. Synthetic compounds :
a) Nitrogen containing :
Procaine, Lignocaine, Benzocaine
b) Non-nitrogenous :
Benzyl alcohol, propanediol
3. Miscellaneous : Clove oil

4.  IDEAL CHARACTERISTICS :
 It should be non-toxic
 It should be non-irritant to the muscular tissue
 It should not cause damage to the nerves
 It should be freely soluble in lipids, as their local
anaesthetic property directly proportional to lipid
solubility.
 It should be effective on topical as well as parenteral
administration.
 It should possess quick onset and a sufficient duration of
action, required complete surgical procedures.

5.  MECHANISM OF ACTION :
 Local anaesthetics act on outer part of cell membrane
 Local anaesthetics are known to reduce the membrane
permability changes to Na+ chief extracellular cation ant
to K+ chief intracellular cation.
 It is belived that Ca++ ions control passage of Na+ across
the cell membrane.
 Local anaesthetics competitively prevent binding of Ca++
to membrane and thus interfers with transport of Na+
across cell membrane
 Thus by decreasing Na+ transport local anaesthetics
reduces threshold potential, thus propagation of action
potential across nerve is blocked & result in anaesthesia.

6.  TECHNIQUES OF APPLICATION :
1. Topical / Surface anaethesia :
 In this technique local anaesthetics are used in the form
of ointment, cream or powder and is directly applied to
the site which is to be anaesthetized.
 It is strictly contraindicated for application to mucus
membrane, damaged skin, wounds & burns
 Applications :
 To reduce pain and itching of ulcers
Drug used – Lignocaine, Amethocaine

7.  TECHNIQUES OF APPLICATION :
2. Infiltration anaesthesia :
 In this technique, anaesthesia is produced by
injecting anaesthetics agent throughout the area to
be anaesthetized. In this, nerve ending are
anaesthetized by direct exposure to drugs.
 Application :
 Used for minor operation like removal of cyst.
Drugs used – Procaine, Lignocaine.

8.  TECHNIQUES OF APPLICATION :
3. Nerve block anasthesia :
 In this technique the anaesthetic agent is injected in
surrounding area of that part which to be operated.
Drug used – Procaine, Lignocaine.

9.  TECHNIQUES OF APPLICATION :
4. Spinal anaesthesia :
 In this technique the drug is injected to the subarachnoid
space.
 After administration, agent reaches to roots of spinal
nerve and dorsal root of ganglia.
 The drug is injected at the site to block roots of those
nerves which innervate the area to be operated.
 Application :
 In gynaecological surgery
Drug used- Lignocaine.

10. 1. LIGNOCAINE :
 It is most common local anaesthetic & most stable
 It has quick onset of action & high degree of penetration
 It is widely used for :
a) Infiltration anaesthesia
b) Intravenous
c) Nerve block
d) Sub-archoid anaesthesia
 The common side effect are bradycardia, hypotension
& some other.

11. 1. LIGNOCAINE :
 Preparations :
 0.25 to 5% solution – Infiltration anaesthesia.
 1 to 2% solution – Nerve block anaesthesia
 2% topical ointment
Addition of adrenaline, 1 in 200000 concentration
prolongs actions of local anaesthetics.

12. 2. PROCAINE :
 It is non-irritant local anaesthetic.
 It is effective rapidly when administered parenterally.
 It is not effective as a topical anaesthetics
 Its duration of action is very short & can be prolonged by
administration of adrenaline.
 It is relatively less toxic, but has a vasodilator property &
can caused hypotension and bradycardia.

13. 2. PROCAINE :
 Preparation :
 1-2% - Central block anaesthesia.
 50-20mg intrathecally – for spinal anaesthesia.
 2% solution – for infiltration anaesthesia.