Medicinal Chemistry of General Anaesthetics Lecture: 01 General anaesthetics are a group of drugs that produce loss of consciousness ; and...
Medicinal Chemistry of General Anaesthetics
Lecture: 01 General anaesthetics are a group of drugs that produce loss of consciousness ; and, therefore, loss of all sensation. The absolute loss of sensation is termed as anaesthesia (derived from the Greek word meaning insensitivity or lack of feeling). General anaesthetics bring about descending depression of the central nervous system ; starting with the cerebral cortex, the basal ganglia, the cerebellum and finally the spinal cord.
These drugs are used in surgical operations to induce unconsciousness ; and, therefore, abolish the sensation of pain. Horace Wells, a Hartford dentist first and foremost demonstrated the usage of nitrous oxide (‘laughing gas’) as an effective surgical anaesthetic in 1844. However, its application as a ‘general anaesthetic’ resurfaced in mid 1860’s when it was dispensed in steel cylinders as an admixture with oxygen. Interestingly, nitrous oxide finds its application even today, particularly in combination with other anaesthetic and analgesic agents.
Later on, William Morton — a Boston dentist demonstrated the anaesthetic actions of diethyl ether in 1846 at the historical ‘‘Ether Dome’’ located at the Massachusetts General Hospital. In actual practice, the usage of diethyl ether followed by cyclopropane were withdrawn completely for being highly toxic amalgamated with equally dangerous physical properties, such as : flammable and explosive.
The anaesthetic agents that have gained cognizance today are invariably hydrocarbons and ethers with halogen (F, Br, Cl) substitution.
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