General anaesthetics (GAs) are

drugs which produce reversible loss of all sensations and consciousness.

Features of GA are :1.Reversible loss of consciousness2.Reversible loss of sensations3.Analgesia & amnesia4.Muscle relaxation & abolition of

reflexes

Classification

1. Inhalational GA – a) Volatile liquids : Ether Halothane Enflurane Isoflurane Desflurane

b) Gas : Nitrous oxide

2. Parenteral GA – a) Inducing drugs – Thiopentone

sodium Propofol Etomidate

b) Slow-acting drugs – BZDs : Diazepam, lorazepam Ketamine : Dissociative

anesthesia Opioids : Fentanyl, alfentanil

Therapeutic uses :

For operations on head, neck & face For induction and maintenance of anaesthesia – cardiac catheterization, bronchoscopy Short procedures – dressing of burns As an adjuvant to anaesthetics for

effective analgesia Postoperative pain

Complications of GA –

A. During anaesthesia : respiratory depression salivation, respiratory secretions cardiac arrhythmias, asystole fall in BP aspiration of gastric contents laryngospasm & asphyxia delirium, convulsions

B. After anaesthesia : nausea & vomiting persisting sedation pneumonia organ toxicities – liver & kidney damage nerve palsies cognitive defects

Local anaestheticsLocal anaesthetics

LAs are drugs which when applied

topically or injected locally, block

nerve conduction & cause reversible

loss of all sensations in the part

supplied by the nerve.

Cocaine

Lignocaine

Benzocaine

Tetracaine

Procaine

Prilocaine

Bupivacaine

Ropivacaine

Mechanism of action -

Local anaesthetics

Block voltage-gated Na+ channels

No entry of Na+ ions into the cell – no depolarization

No generation of action potential

No generation and conduction of impulse to CNS

Local anaesthesia

Therapeutic uses : Anaesthetize mucous membrane of the eyes, nose, mouth, cornea, urinary & upper respiratory tracts

Abscess drainage

Surgery – lower & upper limbs, lower abdomen,

perineum, caesarean section

Excision of small swellings, suturing of cut wounds, dental procedures

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