3. Introduction
Drugs that temporarily blocks sensory/pain signals from nerves
to the centers in the brain
We have different types of anesthetics according to type of
surgical intervention
o Local anesthetics
o Sedation anesthetics
o General anesthetics
4. Local Anesthetic
In local anesthetics we block the sensations of a small section of the
body
Commonly used include lidocaine , bupivacaine ropivacaine,procaine
Mechanism of action reversibly inhibit nerve transmission by binding
voltage-gated sodium channels in the nerve plasma membrane which
prevents action potential initiation and propagation
Clinical application during lumbar puncture , spinal anesthesia , cataract
surgery & root canal
5. Local anesthetic side
effects
Local anesthetic can readily cross the blood brain barrier
and lead to Generalized CNS depression leading to
respiratory depression and arrest
Local anesthetic can also cause cardiac toxicity
1. hypotension
2. Dysrthmias
3. myocardial depression
4. Decreased contractility
6. General Anesthetics
General Anesthetics is a medically induced coma with loss of protective
reflexes
General Anesthetics are usually administered via intravenously or as
inhalation anesthetic
Performed in patients undergoing surgical manipulation procedures that
require deep relaxation for longer periods of time
Used in major surgery like heart surgery , knee or hip replacement
surgery
Examples include isoflurane , desflurane ,propofol etc
8. Inhaled Gas
Anesthetics
We have nitrous oxide also known as laughing gas which is a colourless gas
with sweet scent and taste
Commonly administered in combination with opioid or volatile anesthetics
Mechanism of action is they inhibit the NMDA receptor which causes a
dissociative anesthesia with catalepsy amnesia and analgesia
Common side effects include nausea ,vomiting , fatigue & dizziness serious
side effects is they inactivate vitamin b12 and lead vitamin deficiency and they
are not given to patient with vitamin b12 deficiency
9. Volatile liquids
Anesthetics
Halothane , isoflurane , desflurane & sevoflurane , the most potent of all is
isoflurane and does not undergo any deterioration during storage due to
its great physical stability
Mechanism of action is they act as an positive allosteric modulator of
GABA receptors , potentiate glycine receptors & inhibit NMDA receptors
Side effects include shivering , nausea , vomiting serious side effects
include hepatic toxicity due to fact of formation reactive species
trifluoroacetylated reactive intermediate(TFA) in the case of halothane and
isoflurane while sevoflurane is much safer as it doesn’t produce TFA but a acyl
halide hexafluroisopropanol which doesn’t stimulate hepatitis antibodies
10. Barbiturates
Anesthetics
Thiopental , Thiamylal & methohexital
Barbiturates have two main classes oxybarbiturates & thiobarbiturates
Barbiturates solution are highly alkaline which lead to the formation of water
solube salts
Mechanism of Action is that they act as a GABAa receptor agoinst anf hence
produce cns depression they also reduce cerebral metabolic rate of oxygen
which inturn lead to decreased cerebral blood flow and decreased intracranial
pressure they also increase blood flow to ischemic part of the brain
Side effect include caughing , sneezing , respiratory depression ,severe
hypotension cardiac arrhythmia and is contraindicated in patients with acute
intermittent porphyria as they increase porphyrin synthesis
11. Dissociative
Anesthetics
Ketamine is an analog of phencyclidine which is also known as angel dust
Mechanism of action is they binds preferentially to the NMDA receptors on
inhibitory interneurons in the cortex, limbic system, and hippocampus that
promote uncoordinated increase in neuronal activity and an active EEG
pattern, and produce unconsciousness
Side effects include psychogenic reactions like hallucinations and out of
body experience they also cause tachycardia &hypertensio also cause
hypoxia & increased salvation leading to laryngospsm
12. Opiods Anesthetics
Opiods are used in perioperative care treat acute postoperative pain
Morphine , fentanyl , naloxone , heroin , remifentanyl
Mechanism of action is they are Mu opiate receptor agonist and NMDA receptor
antagonist
Clinical use anlagesia and sedation
Side effects include vomiting , nausea , delayed gastric emptying, constipation, bowel
distension, paralytic ileus, sphincter of Oddi spasm, urinary retention, histamine
release, miosis, muscle rigidity, diffuse CNS effects dizziness, light headedness,
sedation, drowsiness, euphoria, dysphoria , cognitive dysfunction memory loss,
inability to concentrate or focus attention, hallucinations, and cardiovascular effects.
13. Propofol
Most frequently used IV anesthetics and has rapid onset & rapid emergence
from anesthesia
Propofol is primarily metabolised by the liver and excreted by the kidneys
Mechanism of action is they are GABAa receptor agonist and they also reduce
cerebral metabolism of oxygen and inturn reduce cerebral blood flow and
cerebral intracranial pressure
Side effects include pain on injection,serious side effect include PRIS which
contains unexplained metabolic acidosis, hyperkalemia, hyperlipidemia,
rhabdomyolysis, hepatomegaly, renal failure and most importantly ECG
changes, arrhythmias, and progression to cardiac failure
14. Etomidate
Etomidate is imidazole derivative and is not stable in neutral ph
First introduced as an induction agent
Mechanism of action is they act as GABAa receptor agonist and lead
to inhibitory effect on the CNS
Side effects include adrenal suppression by acting on the 11β-
hydroxylase and prevent the converson of cholesterol into cortisol ,
pain on injection , thrombophlebitis & myoclonus
