Intravenous, inhaled anaethetics and opiods.pptx - Intravenous inhaled anaethetics and opiods Dr Joyce Ongaya Overview History Definitions Properties of

Intravenous, inhaled anaethetics and opiods.pptx -...

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Intravenous, inhaled anaethetics and opiods Dr. Joyce Ongaya
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Overview History Definitions Properties of an ideal anaesthetic agent Classification Mechanism of action Indication Effects Side effects and contra- indications New advances Inhalational anaethestics
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HISTORY Wren began intravenous (IV) anesthesia in 1656, using a goose quill and a bladder to inject wine and ale into a dog’s vein. Invention of the hollow needle in 1843 and the hypodermic syringe in 1853 allowed IV administration of drugs. By the 1900s, diverse drugs, including ether, had been given IV for sedation. Redonnet made the first IV barbiturate, Somnifen, in 1920. Weese and Scharpff synthesized the short-acting hexobarbital in 1932, but the introduction of thiopental by Lundy and Tovell in 1934 provided the greater advance. Price suggested in 1960 that thiopental redistribution from brain to muscle, rather than to fat, explained the rapid awakening from thiopental. This work underlay many subsequent pharmacokinetic and pharmacodynamic concepts.
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Definitions
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AIMS OF ANAESTHESIA
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Properties of an ideal anaesthetic agent Physical properties •Water soluble & stable in solution • Stable on exposure to light • Long shelf life • No pain on intravenous injection •Non-irritant when injected subcutaneously • Low incidence of thrombophlebitis • Cheap
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Pharmacokinetic properties • Rapid onset in one arm-brain circulation time • Rapid redistribution to vessel rich tissue •Rapid clearance and metabolism •No active metabolites
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Pharmacodynamics properties • High therapeutic ratio •Minimal cardiovascular and respiratory effects •No histamine release/hypersensitivity reactions • No emetic effects • No involuntary movements •No emergence nightmares •No hang over effect •No adrenocortical suppression • Safe to use in porphyria
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Classification 1) Barbiturates 2) Benzodiazepines 3) Miscellaneous agents (phenols, phencyclidines and imidazoles) 4) Opiods
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Barbiturates Examples Thiopental Thiamylal Pentobarbital Secobarbital Methohexital
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Mechanism of action Enhance transmission of inhibitory neurotransmitters (GABA) . The GABA receptor complex is the most likely site of barbiturate action. Barbiturates both enhance and mimic the action of GABA, by binding to the receptor they, decrease the rate of GABA dissociation increase the duration of GABA activated Cl- channel opening at higher concentrations directly activate Cl- channel
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Indications
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Effects and side- effects Effects Hypnosis Antiepileptic Antianalgesic
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Side- Effects 1. Hypotension 2. Respiratory depression 3.
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