1. GENERAL ANAESTHETIC
AGENTS By
Afsar fathima

2. CONTENTS:
DEFINITION
NEUROPHYSIOLOGIC STATE PRODUCED BY GENERAL ANESTHETICS
DIFFERENCE BETWEEN GENERAL AND LOCAL ANESTHETICS
OVERTON & MEYER CORRELATION
CLASSIFICATION OF GA s
MECHANISM OF ACTION
PHARMACOKINETICS OF DRUGS
TOXICITY OF GA s
SOME PLANTS WITH ANESTHETIC ACTIVITY
REFERENCES

3. DEFINITION:
General anesthetics are drugs which produce reversible loss of all sensation and Consciousness.

4. Inhibition of Autonomic
reflexes
Skeletal muscle relaxation
Unconsciousness
GA s
Amnesia
Analgesia

5. Properties
General Anesthetics
Local Anesthetics
Site of Action
Area of body involved
Consciousness
Care of Vital functions
Poor health in patient
Use in non co-operative
patients
Major surgeries
Minor surgeries
CNS
Whole body
Lost
Essential
Risky
Possible
Preferred
Not Preferred
Peripheral Nerves
Restricted area
Unaltered
Usually not needed
Safer
Not possible
Cannot be used

6. MINIMAL ALVEOLAR CONCENTRATION (MAC):
A measure of potency
1MAC is the concentration necessary to prevent responding in 50% of population.

7. STAGES OF GENERAL ANESTHESIA:
I. STATE OF ANALGESIA
II. STATE OF EXCITEMENT AND DELIRIUM
III. STATE OF SURGICAL ANESTHESIA
IV. MEDULLARY PARALYSIS

8. PATHWAY OF GENERAL ANESTHETICS:

9. ANESTHETICS
GENERAL
premedication
Induction of
anesthesia
Maintenance Of

10. I. Relief from anxiety(Benzodiaepines) III. Post – operative
INTRA VENOUS
ANESTHETICS
PREMEDICATION
INHALATION
ANESTHETICS
I. Relief from anxiety(Benzodiaepines)
II. Reduction in secretions
and vagal reflexes
(hyoscine/Atropine)
III. Post – operative
(Anti- emetics)
IV. Pain Relief (NSAIDs,
Opioid analgesics)
(Thiopental)
# Barbiturates
# Non- Barbiturates
a. Propofol
b. Etomidate
c. ketamine
Nitrous oxide
Halothane
Isoflurane
Enflurane
Desflurane
Sevoflurane

11. MECHANISM OF ACTION:

13. Amount that reaches the brain
PHARMACOKINETICS OF INHALED ANESTHETICS:
Amount that reaches the brain
Indicated by oil:gas ratio (lipid solubility)
Partial Pressure of anesthetics
5% anesthetics = 38 mmHg
Solubility of gas into blood
The lower the blood:gas ratio, the more anesthetics will arrive at the brain
Cardiac Output
Increased CO= greater Induction time

15. PHARMACOKINETIC PROPERTIES OF IV ANESTHETICS:

16. TOXICITY OF ANESTHETIC AGENTS:
ACUTE TOXICITY
NEPHROTOXICITY
HEMATOTOXICITY
MALIGNANT
HYPERTHERMIA
HEPATOTOXICITY
CHRONIC TOXICITY
MUTAGENICITY
TERATOGENICITY
REPRODUCTIVE
EFFECTS
CARCINOGENICITY

17. SOME PLANTS SHOWING ANESTHETIC ACTIVITY:
Datura metel
Brugmansia species
Winter green( used for arthritis, aching muscle, gout)
Theophrastus
Pedanius dioscorides

18. REFERENCES:
Basic and clinical pharmacology- katzung, RogerJ.Porter,MD ,& Brain S. Meldrum,MB, PhD 11th edition
RANG & DALE’S Pharmacology 7th edition
Essentials of Medical Pharmacology, KD Tripathi
Medical Pharmacology at a Glance, Michael J Neal
Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 11th edition.