drugs used in surgery

drugs used in surgery

1. general anaesthetics

   • use and effects
     • jany CNS functions depressed
     • abolish awareness and response to pain
     • used in surgery
     • loss of consciousness/memory
     • suppression of pain
     • suppression of skeletal muscle reflexes and tone
     • adverse effects
       • lowers blood pressure and respiration
         • low therapeutic index
       • lover/kidney damage
         • rarely
   • characteristic of dad anaesthetic
     • low solubility i blood
       • giving rapid blood saturation
     • high potency
       • hih lipid soluability
     • reversiblity
       • gasses go good control /, injections less so
     • good analgesia
     • amnesia
     • no hangover
     • low/ harmless metabolism
     • non flammable
     • muscle relaxation
     • low toxicity
   • typesof anaesthetics
     • volitile/gaseous
       • simple unreactive compounds
       • halothane and nitrous oxide commonly used
       • numerous simple small compounds
     • intravenous agents
       • IV injection
         • very rapid
           • high cerebral blood flow
         • short duration
           • redistribution to other organs
       • thiopentone (barbiturate)
         • low therapeutic index
         • decreases heart and respiration
         • repeat dose
           • longer anaestesia
             • slow metabollism
       • can be used to
         • induce anaesthesia in prepration for other agents
         • short small procedures

2. Drug adjuncts to anaesthesia:pre medication

   • hyoscine
     • muscarinic receptor antagonist
     • dries up secretions of saliva and bronchial mucus
   • morphine
     • opiate analgesic
     • prevents post-operative pain
   • lignocaine
     • local anaesthetic
     • blocks conduction in sensry nerves
   • muscle relaxant drugs
     • Voluntary muscles can be relaxed by drugs which interfere with nicotinic receptors
     • tubocurarine
       • non depolarising
       • competes with ACh
       • long acting
       • reversiblewithChE inhibitor
     • suxamethonium
       • depolarising
       • cation channels stay open
       • short acting
       • Not reversible with ChE inhibitor

3. mechanisms of anaesthetics

   • synaptic transmission, not axonal conduction
   • analgesia
     • reticular formation and thalamus
   • unconsciousness
     • RF and hippocampus
   • amnesia
     • hippocampus
   • lipid soluability
     • interact with hydrophobic structure
     • membranes
       • volume expansion, pressure reversal
     • protein binding (hydrophobic sites
   • receptors encourage opening of chloride channels (eg GABA receptors)
     • Cl- entry into neurone
       • hyperpolarisaion and inhibition