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ThiopentoneType of DrugBarbiturate – ultra-short actingIndicationInduction of General Anaesthesia Mode of ActionInhibits GABA receptors in CNS. Causes hypnotic & sedative effects & has anticonvulsant properties. No analgesic properties.Dose2-5mg/kg as IV bolusAmpoule500mg powder, made up with 20mL water. Standard dilution = 25mg/mLPharmocokinetics notesTime to effect one arm-brain-circulation time. Fast onset action due to high cerebral blood flow and highly lipid soluble. Duration of action 5-15mins. Off-set of action due to re-distribution to other tissues (muscle, then fat), metabolism by liver. EFFECTS by Systems:CVSNegative inotropy↓ cardiac output by 20%↓ SVRResulting ↓ BPHR can ↑ as compensationRespPotent respiratory depressantCan cause bronchospasmCNS↓ CBF↓ ICPAnticonvulsant activityOtherPost-op nausea & vomiting prominent.Special PointsTissue necrosis if extravasation occurs.Can precipitate with neuromuscular blockers – ensure flushed well between administration .Section 29 drug.Is traditional drug for RSI & is still drug of choice for RSI in AED. In theatres – trend to use propofol instead for RSI.PROPOFOLType of DrugPhenol derivative (not expected to remember!)IndicationInduction of General Anaesthetic. Agent for procedural sedation.Sedation post intubationMode of ActionUnclear modeDose1-2mg/kg as IV bolus for inductionFor sedation post intubation – infusion of 10mL/hr (ie: 100mg/hr) upwards, “standard” dose is 20mL/hr Ampoule200mg in 20mL ampoule in white oil-in-water emulsion. Concentration = 10mg/mLPharmocokinetics notesLOC occurs in approx. 30secs.Highly protein bound. Waking in 10 minutes.Metabolism by liver.EFFECTS by Systems:CVS↓CO↓BP↓ SVPNo change in HRRespDose –dep reduction in ventilation. Apnoea after bolus SSmooth induction. Smooth awakening without CNS effectsOtherAntiemetic propertiesInvoluntary movements can occur but are not epileptiform on EEGsSpecial PointsPainful to injectionNo analgesic properties.Contains purified egg lecithin (yolk component) & soya bean oil. (within anaesthesia literature – no evidence so far to avoid in pts with egg or soy allergies)EtomidateType of DrugCarboxylated imidazole derivative (not expected to remember!)IndicationInduction of general anaesthesiaMode of ActionActs on GABA receptorsDose0.2-0.3mg/kg as IV bolusAmpoule20mg in 10mL ampoule – in lipid emulsion.Concentration = 2mg/mLPharmocokinetics notesActs in 10-60 secs, duration of action 6-8 minsNon-cumulative on repeated dosing as rapidly metabolised by plasma & hepatic esterasesEFFECTS by Systems:CVSRelative cardiovascular stability RespDose –related ↓ RR & VtTransient apnoea . coughing / hiccupping can occurCNS↓ CBF, ICP & cerebral metabolic rate.Involuntary muscle movements, tremors, hypertonia can occur.Epileptiform EEGs can occur in 20% ptsOtherPotent inhibitor of steroidogenesis – ie: ↓ cortisol & aldosterone for 24hrs post single dose.Special PointsPain on injection.Section 29 drug.KetamineType of DrugPhencyclidine derivativeIndicationInduction of anaesthesiaProcedural sedationMode of ActionNon-competetive antagonist as NMDA receptor.May modulate opioid & muscarinic receptorsDose1.5-2mg IV bolus over 60seconds(other routes not discussed here)Ampoule200mg/2mL ampule. Dilute to 20mL salineConcentration = 10mg/mLPharmocokinetics notesOnset action 30secs, duration 5-10 minsEFFECTS by Systems:CVS↑ HR↑ BP↑ CO↑ sympathetic toneRespSli ↑ RRAirway reflexes preservedBronchodilation is a featureCNSDissociative anaesthesia Amnesia↑ CBR↑ cerebral metabolic rateEmergence delirium, unpleasant dreams & hallucinations - reduced by quiet awakeningOtherPost-op nausea & vomiting common↑ salivationSpecial PointsIn Controlled Drug cupboard.SuxamethoniumType of DrugDepolarising neuromuscular blockerIndicationRapid & profound paralysis to facilitate intubationMode of ActionProlonged depolarisation of skeletal muscles by attachment to post-synaptic membrane. Depolarised NMJ cannot respond to new acetylcholine Dose1mg/kgAmpoule100mg in 2mL plastic ampoule with red writing. Use undiluted.Kept refrigerated.Pharmocokinetics notesOnset action 30seconds as evidenced by generalised muscular contractions & fasiculations. Duration 3-5minutes.Metabolised by plasma cholinesterases.EFFECTS by Systems:CVSBradycardia if repeated dosesRespApnoeaCNS↑ ICP ↑ intraocular pressureOther↑ K levels by 0.4mmol/L↑ intragastric pressure↓ lower oesophageal sphincter toneSpecial PointsAtypical plasma cholinesterases can cause a prolonged blockade of 1-3 hrs. Potent trigger of malignant hyperthermia.Hyperkalaemic response is exaggerated ( with potential VF arrest) inBurns (after 24-48hrs, & can last up to 1-2 yrs)Denervated skeletal muscles leading to atrophy (eg: post spinal cord injury) from 96 hrs post denervationMuscular dystrophySevere skeletal muscular traumaRocuroniumType of DrugNon-depolarising neuro-muscular blockerIndicationParalysis for intubation and control of ventilation.Used for RSI when suxamethonium is contraindicatedMode of ActionCompetitive antagonist of acetylcholine at the post-synaptic membrane of neuromuscular junction.Dose0.6mg/kg is standard intubating dose - intubate after 60- 90 secs1mg/kg – intubation in 45 secs ( similar to suxamethonium)AmpouleAmpoule of 5mL, concentration = 10mg/mL Pharmocokinetics notesExcreted by hepatic route. Duration of action depends on dose used 30-40mins for standard doseup to 1 hour for higher dose.EFFECTS by Systems:CVSNilRespApnoeaCNSNilOtherSpecial PointsUse of Rocuronium as a paralysing agent mandates that the pt is easy to ventilate prior to paralysis, and airway assessment indicates an easy intubation. NEVER use if any doubt exists !There is a reversal agent (Sugammadex) that provides rapid reversal of Rocuronium– but at the profound blockage stage post RSI, onset of action can still be up to 6-7 minutes - long enough that hypoxic brain injury would occur if you can’t oxygenate. It is NOT available in AED.Precipitates with thiopentone.Safe in patients with malignant hyperthermia.Metaraminol Type of DrugSynthetic sympathomimeticIndicationManagement of hypotensionMode of ActionDirect * & Indirect # sympathomimetic agonist. Acts predominantly at alpha adrenoreceptorsDose0.5mg – 1mg boluses , titrating to effectAmpoule10mg/mL ampoule. Dilute into 20mL syringe with salineConcentration = 0.5mg/mLPharmocokinetics notesOnset 1-2mins.Maximum effect at 10minsEFFECTS by Systems:CVS↑ SBP↑ DBPReflex ↓ HR occursPositive inotropyRespCNS↓ CBFOtherSpecial PointsDirect *Binds at receptor to activate it directlyIndirect#Binds at postganglionic sympathetic nerve endings to cause release of neurotransmitter ................
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