General anesthetics are drugs that induce reversible anesthesia, causing loss of sensation including pain and consciousness. They have four main effects - loss of sensation, unconsciousness and amnesia, immobility and muscle relaxation, and abolition of reflexes. General anesthetics are classified as either volatile/inhalational anesthetics or non-volatile/intravenous anesthetics. They work primarily by increasing inhibition of neurons through the GABAA receptor, allowing more chloride ions to flow into neurons and reduce their ability to fire. Ketamine blocks the NMDA receptor, decreasing neural excitation.

1. General Anaesthetics
Mr. Shashank Shekhar Mishra

2. Anaesthesia
 Anaesthesia is the reversible condition
induced by anaesthetic drugs that cause
reduction or complete loss of response to pain
or another sensation such as consciousness or
muscle movement during surgery.

3. Anaesthetics
• These are drugs which produce anaesthesia.

4. General Anaesthetics
 These are the drugs which produce reversible
loss of all sensation and consciousness.
 The cardinal features of G.A. are-
 The loss of all sensations, especially pain
 Sleep (Unconsciousness) and amnesia
 Immobility and muscle relaxation
 Abolition of reflexes.

5. Classification
I. Volatile OR Inhalational Anaesthetics:

7. II. Non-volatile OR Intravenous Anaesthetics:

8. Synthesis of Halothane

9. Synthesis of Methohexital sodium

10. Synthesis of Ketamine HCl

11. Mechanism of action of General
anesthetics
 General anaesthetics work by altering the activity of specific neurons in the
brain. General anaesthetics excluding Ketamine works primarily by
increasing the activity of inhibitory GABAA receptors.
 The GABAA receptor is a channel that allows chloride ions to flow into the
neuron, decreasing the voltage within the cell relative to the extracellular
space. Such hyperpolarization decreases the probability that the neuron will
fire. Halothane and sevoflurane increase the chloride current going into the
cell, making the inhibition more potent.

13. The NMDA receptor allows sodium and calcium ions to
flow into the cell, while letting potassium ions out,
increasing the voltage within the cell relative to the
extracellular space and increasing the probability of
neural firing. Ketamine blocks this receptor, decreasing
its excitatory actions.

14. Thank You