PHARMACOLOGY IS CHALLENGING SUBJECT TO TEACH AND UNDERSTAND ALSO .....THEIR INTERESTING PART IS TO LEARN ABOUT GENERAL ANESTHETICS AND PRE ANESTHETICS

1. General Anesthetics & Pre-Anesthetics
 BY
 ASAWE TEJASWINI L
 DEPARTMENT OF PHARMACOLOGY
 ASSIASTANT PROFESSOR
 SIDHHIS INSTITUTE OF PHARMACY
 THANE

2. General Anesthetics
 an anaesthetic that affects the whole body and
usually causes a loss of consciousness.
 The goal of general anesthesia is to produce
analgesia, unconsciousness and amnesia
 Loss of pain perception, Loss of awareness of one’s
surrounding, Inability to recall what took place

3. History of Anesthesia

5. Stages of Anesthesia
 There are 4 stages of Anesthesia
 Stage 1 : The Analgesia :
 The Analgesia stage begins with the inhalation of anesthesia
 Pain is Progressively abolished during this stage
 Patient remains conscious, can hear and see, and feels like a
dream state
 Stage 2 : The Excitement/Stage of Delirium :
 It starts from loss of consciousness to beginning of regular
respiration.
 Excitement is seen and the patient may shout, struggle and
hold breath, jaws are tightly closed.
 Vomiting, may occur.
 Heart rate & BP may rise and pupils dilate due to
sympathetic stimulation

6.  Stage 3 : Surgical Anesthesia :
 Moving eyeballs this stage ends when eyes becomes fixed
 Loss of corneal and Laryngeal reflexes
 Pupil start dilating and light reflex is lost.
 Stage 4 : Medullary Paralysis:
 This is the stage between respiratory arrest
and death due to circulatory collapse.
 In this stage medullary paralysis
cardiovascular & respiratory centres in
medulla are suppressed by anesthetics.

7. CLASSIFICATION OF GENERAL ANETHETICS

8. Classification
 A) Inhalation anesthetic –
 I. Nitrous oxide
 II. Cyclopropane
 Have rapid onset of action and rapid recovery
 III.Ethylene-
 Less toxic than other gas anesthetics
 B) Liquids
 Ether , Halothane , Isoflurane , Desflurane ,
Methoxyflurane .

9.  B) Intravenous anesthetic –
 a) Inducing agents
 Thiopentone sodium , Methohexitone sodium ,
Propofol
 b)Slowly Acting Drug –
 i)Benzodiazepins – Diazepam , Lorazepam ,
Midazolam
 ii)Dissociative anesthetics –
 Iii)Opoid analgesia

10. Anesthetic Agents
 The first attempt to use of “Intravenous Anesthesia” (they
quickly achieve high concentrations in the central nervous
system. ) was Discovered by “WREN” in 1656.
 “THIOPENTAL” is a barbiturate
 It is water soluble & alkaline in nature
 Thiopental produce rapid onset of actions and ultrashorts
recovery period
 It produce mild direct cardiac depression resulting into lower
BP.
 It is used for rapid control of convulsion.

11. Nitrous Oxide
• widely used
• Potent analgesic
• Produce a light anesthesia
• Do not depress the
respiration/vasomotor center
• Used ad adjunct to supplement
other inhalationals

12. Halothane
•Halothane is flurinated volatile
liquid with sweet odour , non irritant
, non-flammable, stored in amber
colured bottle .
• It is potent anesthetic .
•Non irritant , controls hypotension
•Potent and speedy recovery .
•Special apparatus is required for
administration.
•Reduce cardiac output

13. Isoflurane
smooth and rapid induction and
recovery
 very little metabolism (0.2%)
 most widely employed
 It producess less myocardial depression.
 Low nausea and vomitting
 It producess uterine muscle relaxation .
 It is expensive

14. Enflurane
 Enflurane is non- inflammable with mild sweet odour and boils at
57° C.
 Its action is similar to halothane .
 Rapid, smooth induction and maintenance
 2-10% metabolized in liver
 Introduced as replacement for halothane
 Depresses myocardial force of contraction and sensitize heart to
adrenalin
 Metabolism releases fluoride ion causes renal toxicity

15. Intravenous Induction Agents
 Commonly used IV induction
agents
Propofol
Thiopental sodium
Ketamine

16. Intravenous Anesthetics
• Intravenous (i.v.) anesthetics are unique drugs that
induce anesthesia rapidly as they quickly achieve
high concentrations in the central nervous system.
• Most exert their actions by potentiating GABAA
receptor

17. Thiopental sodium
• rapid onset (20 sec)
• short-acting iv anesthetics.
 Effect terminated not by metabolism but by
redistribution

18. Side effects
 Hypotension
 apnoea
 airway obstruction

19. Propofol
 Short-acting agent used for the
induction
 maintenance of GA and
sedation
 Onset within one minute of
injection

20.  It is highly protein bound in vivo and is metabolised
in the liver
Side-effect
 pain on injection
 hypotension
 transient apnoea following induction

21. Ketamine
 NMDA Receptor Antagonist
 usually stimulate circulatory system

22.  “METHOHEXITAL” it is similar to thiopentone and
three times more potent
 It has a quicker 5-8 min action.
 It more rapidly metabolized than Thiopentone
 “ETOMIDATE” it has direct CNS depressant & GABA
agonist
 “PROPOFOL” produce rapid onset and short duration
action
 It is also produces minimal nausea and vomiting

23. Slow Action Drugs
 “BENZODIAZEPINE(BZD)”
 produce sedation & amnesia by potentiating GABA receptors
 BDZ are poor analgesic
 BDZ decrease muscle tone by central action
 They do not provoke postoperative nausea or vomiting
 “DIAZEPAM” it is water insoluble produce venous irritation
 It is metabolized by liver and it is not redistributed
 “LORAZEPAM” it is similar to DIAZEPAM it is water insoluble produce
venous irritation
 “MIDAZOLAM” it is more potent than diazepam & lorazepam.
 It has minimal cardiac effects.

24. Dissociative Anesthesia
 “KETAMINE” pharmacologically katamine is
related to hallucinogen phencyclidine
 Ketamine has been recommended for operation on
the head & neck has bleed , and asthmatic patients
 It is good for repeated use particularly suitable for
burn dressing
 It may be dangerous for hypertensive & ischemic
heart.

25. Pre-Anesthetics/Pre-operative Medications
 SEDATIVE-HYPNOTIC
 OPIOIDS
 ANTIMETIC
 ANTICHOLINERGICS
 ANTIHISTAMINES
 NUROLEPTICS

26. This use of medication is IMP due to following
reasons
 For relief of Anxiety
 Decrease the Secretion
 Decrease Acidity & volume of Juice

27.  “SEDATIVE-ANTIANXIETY DRUGS”:
 They decreases the anxiety , providing amnesia,
 BZDs drug for preanesthetics, anxiolytics, sedation .
 Ex. Lorazepam , midazolam
 “OPIOIDS” :
 Morphine relieve anxiety.
 Reduce the dose of anesthesia
 It produce Pre- & Post-Operative analgesia
 Presurgical pain

28.  “ANTIMETIC” :
 Antiemetic enhance gastric emptying .
 They are prevent nausea , vomiting in patient
 Metaclopramide is effective in reducing Post-Operative vomiting.
 Ex. metoclopramide 10-20mg
 Domperidone
 “ANTICHOLINERGICS” :
 are drugs that block and inhibit the activity of the
neurotransmitter acetylcholine (ACh) at both central and
peripheral nervous system synapses.
 Atropine or Hyoscine has been used primarily to reduce salivary
& bronchial secretions.

29.  “ANTIHISTAMINES” : These are H2 blockers
 Ranitidine or Famotidine given in night
 Raising pH of gastric juice
 “NUROLEPTICS” :
Chlorpromazine,Trifluoprazine or Haloperidol's
are frequently use in premedication
 Relieve Anxiety
 Have Antiemetic action i.e. controls nausea and
vomiting

30. Thank you have nice day