1. Sadaqat Ali

2.  Definition
 How local anesthetic work
 Moa
 Classification
 Pharmacokinetics
 Clinical uses
 Lidocaine
 Diylocinine
 Spinal cord anesthesia

3. DEFINITION:
Local anesthesia is defined as a loss
of sensation in a circumscribed area of the
body caused by depression of excitation in
nerve endings or an inhibition of the conduction
process in peripheral nerves
LOSS OF SENSATION WITHOUT
INDUCING LOSS OF CONSCIOUSNESS.

4.  Altering the basic potential of nerve membrane
 Altering the threshold
 Decreasing the rate of depolarization
 Prolonging the rate of repolarization

5.  Local anesthetics inhibit depolarization of the
nerve membrane by interfering with both Na+ and
K+ currents.
 The action potential is not propagated because
the threshold level is never attained.
 Local anesthetics act at the cell membrane to
prevent the generation and the conduction of
nerve impulses

8.  Esters:
Cocaine, Procaine. Chloroprocaine , Tetracaine.
 Amides:
Lidocaine, Mepivacaine, Prilocaine, Articaine,
Popivacaine, Etidocaine.
 Ketones:
Dyclonine.
 Quinoline:
Centbucridine

11.  Following injection into the area of nerve fibers to be
blocked, local anesthetics are absorbed into blood.
 Ester-linked local anesthetics are quickly hydrolyzed
by butyrylcholinesterase in blood.
 Amide-linked local anesthetics can be widely
distributed via circulation. Amide- linked local
anesthetics are hydrolyzed by liver microsomal
enzymes.
 Thus, half lifes of these drugs are significantly longer
and toxicity is more likely to occur in patients with
impaired liver function.

12. Absorption of local anesthetics is affected by
following factors:
– dosage,
– site of injection
– drug-tissue-binding and
– Presence of vaso-constricting drugs

13.  Analgesia
 Regional anesthesia
 Prevention and treatment of cardiac arrhythmias
 Prevention/management: increased intracranial
pressure
 Treatment of grand mal seizure

14.  CNS
Low doses: tremors and oral numbness,
with possible dizziness, confusion and
agitation (exception = cocaine)
Mod. doses: convulsions (immediately
preceded by muscle twitching); prevented by
injection of anti-convulsant
High doses: possible respiratory depression

15.  Cardiovascular:
vasodilation (exception = cocaine)
- less often, myocardial depression
- ventricular contraction possibly leading to
reduced cardiac output,
in the worst case, ventricular arrhythmias and
cardiac
arrest unintentional high plasma levels of LAs, but
can occur with normal IV doses of bupivacaine

16.  Hypersensitivity:
local dermatitis with some topical; rare
systemic allergic response with injected
esters (due to metabolite)

17.  Smooth Muscle
• Depress contractions in the intact bowel
• Relax vascular and bronchial smooth muscle
• May increase the resting tone
• Decrease the contractions of isolated human
uterine muscle.

19.  Cocaine, an ester of benzoic acid and
methylecognine, occurs in abundance in the
leaves of the coca shrub.

20.  Cocaine produces anesthesia by inhibiting
excitation of nerve endings or by blocking
conduction in peripheral nerves. This is achieved
by reversibly binding to and inactivating sodium
channels. Sodium influx through these channels is
necessary for the depolarization of nerve cell
membranes and subsequent propagation of
impulses along the course of the nerve.
Cocaine is the only local anesthetic with
vasoconstrictive properties.

21.  This is a result of its blockade of norepinephrine
reuptake in the autonomic nervous system.
Cocaine binds differentially to the dopamine,
serotonin, and norepinephrine transport proteins
and directly prevents the re-uptake of dopamine,
serotonin, and norepinephrine into pre-synaptic
neurons. Its effect on dopamine levels is most
responsible for the addictive property of cocaine.

22.  PHARMACOKNIETICS
 Absorption
Cocaine is absorbed from all sites of application,
including mucous membranes and gastrointestinal
mucosa. By oral or intra-nasal route, 60 to 80% of
cocaine is absorbed.
 Metabolism
Hepatic. Cocaine is metabolized to
benzoylecgonine and ecgonine methyl ester,
which are both excreted in the urine.

23.  Indication
For the introduction of local (topical) anesthesia of
accessible mucous membranes of the oral,
laryngeal and nasal cavities.

24.  A local anesthetic and cardiac depressant used as
an anti arrhythmia agent.
 Its actions are more intense and its effects more
prolonged than those of procaine.
 its duration of action is shorter than that of
bupivacaine or prilocaine.

25.  Mechanism of action
Lidocaine stabilizes the neuronal membrane by
inhibiting the ionic fluxes required for the initiation
and conduction of impulses thereby effecting local
anesthetic action. Lidocaine alters signal
conduction in neurons by blocking the fast voltage
gated sodium (Na+) channels in the neuronal cell
membrane that are responsible for signal
propagation.

26.  With sufficient blockage the membrane of the
postsynaptic neuron will not depolarize and will
thus fail to transmit an action potential. This
creates the anesthetic effect by not merely
preventing pain signals from propagating to the
brain but by aborting their birth in the first place.

27.  Absorption
information derived from diverse formulations,
concentrations and usages reveals that lidocaine
is completely absorbed following parenteral
administration, its rate of absorption depending,
for example, upon various factors such as the site
of administration and the presence or absence of
a vasoconstrictor agent.
 Metabolism
Primarily hepatic.

28.  Route of elimination
Lidocaine and its metabolites are excreted by the
kidneys.
 Half life
109 minutes
 Toxicity
convulsions, hypoxia, acidosis, bradycardia,
arrhythmias and cardiac arrest

29.  Indication
For production of local or regional anesthesia by
infiltration techniques such as
percutaneous injection and
intravenous regional anesthesia
by peripheral nerve block techniques such as
brachial plexus and intercostal and by central
neural techniques such as lumbar and caudal
epidural blocks.

30.  Dyclonine is an oral anesthetic found in Sucrets,
an over the counter throat lozenge.
 It is also found in some varieties of the Cepacol
sore throat spray.

31.  Mechanism of action
Local anesthetics block both the initiation and
conduction of nerve impulses by decreasing the
neuronal membrane's permeability to sodium ions.
This reversibly stabilizes the membrane and
inhibits depolarization, resulting in the failure of a
propagated action potential and subsequent
conduction blockade.

32.  Absorption
Readily absorbed through mucous membranes
into the systemic circulation.
 Half life
Approximately 30 to 60 minutes.
 Toxicity
cardiovascular system depression, CNS toxicity,
and methemoglobinemia

33.  Indication
Used to provide topical anesthesia of accessible mucous
membranes prior to examination, endoscopy or
instrumentation, or other procedures involving the
esophagus, larynx, mouth, pharynx or throat, respiratory
tract or trachea, urinary tract, or vagina.
Also used to suppress the gag reflex and/or other
laryngeal and esophageal reflexes to facilitate dental
examination or procedures (including oral surgery),
endoscopy, or intubation.
Also used for relief of canker sores, cold sores or fever
blister.

34.  Topical application:
Lidocaine (ointment)
 SC injections

35.  Topical application
Anesthesia of mucous membrane of nose, mouth
throat can be produced by direct application of salts of
many local anesthetics or by suspension of poorly
soluble drugs like tetracain 2 % or lidocain2 %

36.  It is the injection of local anesthetic directly into
the tissue without taking into consideration the
course of nerve
 Lidocain
 Procain
 Bupivacaine

37.  Is produced by SC injection of a solution of LA in
order to anesthetize the region distal to the
injection.
Nerve block
injection of a LA into or about individual peripheral
nerve or peripheral plexuses.

38.  Nerve blocked
 Trigeminal nerve is blocked
 Anesthetic Cartridges + syringes

39.  Intervertibral space
 CSF withdrawal
 Injection procedure

41.  Goodman and Gilman’s the pharmacological
Basis of therapeutics 12th Edition Chapter no
20
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