Class gen and local anaesthPresentation Transcript
Dr. RAGHU PRASADA M S
DEPT. OF PHARMACOLOGY
SSIMS & RC.
General anaesthetics are the drugs which produce
reversible loss of sensation and conciousness.
Loss of sensation
Sleep and Amnesias
Immobility and muscle relaxation
Abolition of somatic and autonomic reflexes
Minimal Alveolar Concentration :-
Is the alveolar concentration of an inhaled anesthetic that
prevents movement in 50 % of patients in response to
standardized stimulus ( surgical incision ).
Stage of analgesia
Stage of delirium
Plane1- Rolling eye balls
Plane2- Loss of corneal and laryngeal reflexes
Plane3- Loss of light reflex
Plane4- Intercostal paralysis
Short-acting agent used for the induction
, maintenance of GA and sedation in
adult patients and pediatric patients
older than 3 years of age.
It is highly protein bound in vivo
and is metabolised by conjugation
in the liver.
Side-effects is pain on injection
hypotension and transient apnea
•Produce a light anesthesia
•Do not depress the
•Used ad adjunct to supplement
• 20% metabolism by P450
• induction of hepatic
• Myocardial depressant (SA
node), sensitization of
catecholamines - arrhythmia
Transient hepatic damage
In repeated exposure
Malignant hyperthermia (MH) is a pharmacogenetic
hypermetabolic state of skeletal muscle induced in
susceptible individuals by inhalational anesthetics
and/or succinylcholine (and maybe by stress or
Rapid, smooth induction and maintenance
• 2-10% metabolized in liver
• Introduced as replacement for halothane
smooth and rapid induction and recovery
very little metabolism (0.2%)
no reports of hepatotoxicity or renotoxicity
most widely employed
rapid onset (20 sec), short-acting
Effect terminated not by metabolism but by
repeated administration or prolonged infusion
approached equilibrium at redistribution sites
Build-up in adipose tissue = very long emergence
NMDA Receptor Antagonist
usually stimulate rather than depress the circulatory
Cataleptic appearance, eyes open, reflexes intact,
purposeless but coordinated movements
Use specific drugs for each component
▪ N20, opioids, ketamine for analgesia
▪ Produce amnesia, and preferably
▪ inhaled agent
▪ IV hypnotic (propofol, midazolam, diazepam,
▪ Muscle relaxants
Local anaesthetics as distinguished from general
anaesthetics as they abolish the pain and other
sensations in localized areas without affecting the
degree of consciousness of the patient
Drugs that cause reversible loss of sensory
perception specially of pain in a restricted
area of the body, when applied topically or
LA if applied to a mixed nerve—sensory and
motor impulses are interrupted—resulting in
muscular paralysis and loss of autonomic
Reversibly block the impulse conduction
Transient loss of sensation
Local anaesthesia blockade
C,B > Aδ > Aα,ß,γ
Vasoconstrictor is a substance used to keep the
anesthetic solution in place at a longer period and
prolongs the action of the drug
Vasoconstrictor delays the absorption which slows
down the absorption into the bloodstream
Vasoconstrictor used ---the natural hormone called
Blockage of membrane depolarisation in all excitable
tissues, usually intended on peripheral nerve
They prevent the
Initiation and propa-
Gation of the nerve
Impulse by reducing
the passage of Na
Effects of LA: injection as acid (hydrochloric salt)=
ionized form at physiological pH dissociation to
free base (lipid soluble) passage through cell
membrane to interior of axon re-ionisation
enter and blockage of Na+-channel and thereby
preventing influx of Na+ no generation of AP
They block nerve conduction by reducing the
permeability of Na ions during depolarisation
Should not benot be coadministered for nerve block in areas such
as fingers and toes that are supplied with end-arteries
because it may cause ischemia or necrosis
It should be used cautiously in patients in labour and in
patients with thyrotoxicosis or cardiovascular disease.
Usually at range 7.6 – 8.9
Decrease in pH shifts equilibrium toward the ionized
form, delaying the onset action.
Lower pH, solution more acidic, gives slower onset
Presence of Pus and inflammation will retard the
action of LA. ( probably low acidic pH)
Most widely used Amide linked LA and most
Has variety of applications like Local, nerve block,
spinal, epidural, IVRA.
When used locally action starts within 3 mts and
Overdose causes muscle twitchings, convulsions,
cardiac arrhythmias, fall in BP, coma, respiratory
Most popular ant arrhythmic drug
• Standard agent for infiltrations, regional blocks or
• Short onset time, intermediate duration of action
• Class Ib antiarrhythmic properties
• Medium toxicity
• Maximal recommended dose: 3 mg/kg, 6 mg/kg with
A potent long acting ---Amide linked LA available in
India, most widely used allover.
Not used for IVRA but all others like local, spinal
Action lasts for 2 to 3 hours. Strength for epidural is
0.25 to 0.5 % solution.
Has high lipid solubility, distributes more in tissues
than in blood
It is similar to Bupivacaine
One of the metabolites are toxic and can cause
Used for Nerve Blocks and IVRA.
Causes more sensory block, than motor block the
advantage taken in during Caesarean Section.
Bupivacaine is more prone to prolong QTc interval
and induce ventricular tachycardia or Cardiac
depression----( Membrane Stabilization action )
( toxic doses and accidental entry into vessel)-
should not be used for IVRA.
Longest acting LA available in India now.
1. Surface anesthesia
2. Infiltration anesthesia
3. Conduction block a. Field block b. Nerve Block
4. Spinal anesthesia
5. Epidural anesthesia
6. I V R A (Bier’s Block)
Amethocaine ---eye, throat, urethra, rectum and
Benzocaine and Lidocaine hydrochloride—same
---except for eye.
Procaine is unsuitable as a surface ana. Because of
its poor penetrating power
Lignocaine --4 % topical solution, 2 % Jelly
2 % vials for injections
Eutectic : Lowering of melting point of two solids
when they are mixed.
combination of Lidocaine and Prilocaine.
For Pediatric purpose. It can penetrate intact skin.
I v .cannula inserting.
Split skin graft harvesting
Other superficial procedures.
Mech. of action : Nerve endings as exposed to the
drug there by action.
Procaine, Lignocaine 2 % are used either with or
without Adrenaline 1 : 2,00,000
C/I : blocking where end arteries are involved either
for Penis, or for Digits, C A D patients.
Drug is injected close to the nerve or big nerve
trunks eg. Brachial Block, Sciatic, Femoral Nerve,
Radial, Ulnar Nerves.
LA is injected into the subarachnoid space.
Injection is made heavy by adding dextrose or light
by adding saline.
When the anesthetic in injected outside the dura,
the technique is known as Epidural anesthesia.
Lignocaine, Bupivacaine the two agents most
commonly used regularly in anesthesia practice.
Intravenous regional anesthesia
Agent of choice------ Lignocaine (Xylocaine )
20 to 40 ml of 0.5 % Lidocaine is used
Used for only for Upper Limb orthopedic surgeries
and others on Up. Limb.
We have seen all Local actions of LA s
Systemic action when given IV : Bupivacaine is
relatively more cardiotoxic , produces ventricular
tachycardia or fibrillation.
Lidocaine has little effect on contractility and
conductivity, used as antiarrhythmic.
The prominent cardiac action of Xylocaine is
suppression of automaticity in ectopic foci.
Depression of function of CNS and CVS when high
plasma concentrations are reached
CNS toxicity : usually before cardiovacular effects
First signs of excitation due to initial blockade of
mild: circumoral tingling, metallic taste, tinnitus,
visual disturbance, slurred speech
moderate: altered consicous state, convulsions
Later sings of generalized CNS depression with
potentially fatal toxicity: coma,respiratory arrest
1.Bradycardia, 2.Hypotension 3.Headache
4.Cauda Equina syndrome 5.Septic meningitis
EPIDURAL ANESTHESIA :
Here the drug is injected outside the dura. Drug
spread is restricted to a specific region causes fewer
Allergic reactions: common with ESTERS like
Procaine, caused by para-aminobenzoic acid (also
found to cause arachnoiditis), less common with
AMIDES, then mostly through preservatives
Drug interactions: i.e. Anticholinesterases, other
competing drugs hydrolyzed by Plasma CE
Attention with heavy sedation with anticonvulsants:
may mask early signs of toxicity
Methaemoglobinaemia: after large doses Prilocaine