Anesthetics

AnestheticsAnesthetics Priestly discovered first inhalation anesthetic nitrous oxide Priestly discovered first inhalation anesthetic nitrous oxide

•• Loss of sensation Loss of sensation

•• Insensibility to the vital organs Insensibility to the vital organs

•• Loss of consciousness is reversible Loss of consciousness is reversible

•• Temporary insensibility to pain or feeling in the bodyTemporary insensibility to pain or feeling in the body

Characteristics of anesthetic agentCharacteristics of anesthetic agent

•• Should give enough relaxation timeShould give enough relaxation time

•• Inert, potent, non-flammable, non-irritatingInert, potent, non-flammable, non-irritating

•• Should not have toxic effectShould not have toxic effect

•• Stable to light and heatStable to light and heat

•• EconomicalEconomical

•• Analgesic action and muscle relaxationAnalgesic action and muscle relaxation

•• Should not induce vomitingShould not induce vomiting

•• Should not reduce blood pressureShould not reduce blood pressure

•• Should not have any adverse effect with the administration of other drugs.Should not have any adverse effect with the administration of other drugs.

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Classification of anestheticsClassification of anesthetics1. General anesthetics1. General anesthetics

2. Local anesthetics2. Local anesthetics

General anesthetics are further classified intoGeneral anesthetics are further classified into

a. Volatile general anesthetics a. Volatile general anesthetics

b. Non-volatile anestheticsb. Non-volatile anesthetics

Some of Volatile general anestheticsSome of Volatile general anesthetics

EtherEther

•• Anesthetic ether is 96-98% diethyl etherAnesthetic ether is 96-98% diethyl ether•• Colourless volatile liquid with pungent smellColourless volatile liquid with pungent smell

•• Soluble in organic solvents like alcohol, chloroform, etc.Soluble in organic solvents like alcohol, chloroform, etc.•• Prepared by williamson’s synthesisPrepared by williamson’s synthesis•• Stored in well-closed, light resistant bottlesStored in well-closed, light resistant bottles•• Inflammable.Inflammable.•• When exposed in air it forms peroxides or acetic When exposed in air it forms peroxides or acetic

aldehydesaldehydes•• Stabilizers like sodium pyrogallate are added Stabilizers like sodium pyrogallate are added •• Stored in internally copper plated containers.Stored in internally copper plated containers.

..AdvantagesAdvantages

•• Induces surgical anesthetics without pre- anesthetics medicationInduces surgical anesthetics without pre- anesthetics medication•• SafeSafe•• Produces muscular relaxationProduces muscular relaxation•• Does not modify blood pressureDoes not modify blood pressure•• Economical and stableEconomical and stable•• Administered without a complicated processAdministered without a complicated process

DisadvantagesDisadvantages

•• Induction is slowInduction is slow•• Boils at low temperatureBoils at low temperature•• InflammableInflammable•• Vapours are irritating to mucous membraneVapours are irritating to mucous membrane•• Nausea and vomiting appear Nausea and vomiting appear •• Slow recoverySlow recovery•• Ether convulsions may occur in childrenEther convulsions may occur in children

..Derivatives of ether were found to be less irritating than Derivatives of ether were found to be less irritating than etherether

Methyl-n-propyl etherMethyl-n-propyl ether•• Powerful than ethyl ether Powerful than ethyl ether •• Less adverse side effectsLess adverse side effectsVinyl etherVinyl ether•• Colourless liquidColourless liquid•• Miscible with alcohol, ether and chloroformMiscible with alcohol, ether and chloroform•• Stored in well closed containerStored in well closed container•• Stored in cool, dark place Stored in cool, dark place AdvantagesAdvantages•• More potentMore potent•• Speedy recoverySpeedy recovery•• Useful in Dental proceduresUseful in Dental procedures•• Used in minor operations for short durationUsed in minor operations for short durationDisadvantages Disadvantages •• Damages liverDamages liver•• InflammableInflammable

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Chloroform Chloroform

•• Powerful volatile liquid Powerful volatile liquid

•• Prepared from bleaching powder and ethyl alcoholPrepared from bleaching powder and ethyl alcohol

•• Colourless volatile liquidColourless volatile liquid

•• 1-2% of ethanol is added to prevent the formation of 1-2% of ethanol is added to prevent the formation of poisonous phosgene gaspoisonous phosgene gas

•• Should be protected from light Should be protected from light

AdvantagesAdvantages

•• Induction is promptInduction is prompt

•• Vapours are not flammableVapours are not flammable

•• Used in obstetrical anestheticsUsed in obstetrical anesthetics


•• ToxicToxic

•• Liver and cardiac toxicityLiver and cardiac toxicity

•• Due to its toxicity chloroform is no longer usedDue to its toxicity chloroform is no longer used

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HalothaneHalothane

•• Fluorinated volatile liquid Fluorinated volatile liquid

•• Structure similar to chloroformStructure similar to chloroform

•• Heavy colourless liquid Heavy colourless liquid

•• Non-flammableNon-flammable

•• Sweet fruity odour Sweet fruity odour

•• Miscible with chloroform, ether, etc.Miscible with chloroform, ether, etc.

•• Stored in air tight containers at low temperatureStored in air tight containers at low temperature

•• Should be protected from lightShould be protected from light

•• Stable in presence of alkalisStable in presence of alkalis

..AdvantagesAdvantages•• Not flammable Not flammable •• Does not irritate the respiratory passageDoes not irritate the respiratory passage•• Nice pleasant odourNice pleasant odour•• Potent anesthetics Potent anesthetics •• Post operative vomiting is low Post operative vomiting is low •• Relaxes bronchial muscle Relaxes bronchial muscle •• Safe Safe •• Used as anesthetic during plastic surgery Used as anesthetic during plastic surgery

DisadvantagesDisadvantages•• Causes cardiovascular depression Causes cardiovascular depression •• Depresses respirationDepresses respiration•• Poor analgesicPoor analgesic•• ExpensiveExpensive•• Has to be given through a special apparatusHas to be given through a special apparatus•• Hepatic damageHepatic damage•• Used for intro-abdominal operationUsed for intro-abdominal operation

..TrichloroethyleneTrichloroethylene

•• ColourlessColourless

•• Characteristic odourCharacteristic odour

•• Thymol is added as preservativeThymol is added as preservative

•• Immiscible in waterImmiscible in water

•• Miscible with alcohol, chloroform, ether, etcMiscible with alcohol, chloroform, ether, etc

•• Stored in air tight and light resistant containersStored in air tight and light resistant containers

•• Kept in cool placesKept in cool places


•• PotentPotent

•• Rapid onset of actionRapid onset of action

•• Recommended for short procedures such as dental extractions, etc.Recommended for short procedures such as dental extractions, etc.

•• Used for migraine pain, angina pectoris and child birthUsed for migraine pain, angina pectoris and child birth


•• Poor muscular relaxationPoor muscular relaxation

•• May be hepatotoxic and tachypnoea May be hepatotoxic and tachypnoea

•• Breaks down in the presence of soda lime to give highly toxic productsBreaks down in the presence of soda lime to give highly toxic products

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Ethyl chlorideEthyl chloride•• Non- irritatingNon- irritating

•• Highly volatile Highly volatile

•• Inflammable Inflammable

•• At ordinary temperature and pressure it is a gas At ordinary temperature and pressure it is a gas

•• Pleasant characteristic odourPleasant characteristic odour

•• Miscible with organic solvents like alcohol and ether Miscible with organic solvents like alcohol and ether

•• Slightly miscible in waterSlightly miscible in water

•• Stored in air tight containersStored in air tight containers

•• When sprayed on skin it evaporates rapidly and cools the skinWhen sprayed on skin it evaporates rapidly and cools the skin

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•• Used as local anesthetic for minor operations such as incision, etcUsed as local anesthetic for minor operations such as incision, etc

•• As general anesthetic it induces anesthetic within 1 or 2 minutesAs general anesthetic it induces anesthetic within 1 or 2 minutes

•• Quick inductionQuick induction


•• May damage liver May damage liver

•• Induce cardiac arrhythmias or cardiac arrest Induce cardiac arrhythmias or cardiac arrest

•• Poor muscle relaxationPoor muscle relaxation

•• Low safetyLow safety

•• Difficult to maintain steady depth of anestheticDifficult to maintain steady depth of anesthetic

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Nitrous oxideNitrous oxide•• Colourless inorganic, non-irritatingColourless inorganic, non-irritating•• Sweet taste Sweet taste •• Non-flammableNon-flammable•• Available in steel cylindersAvailable in steel cylinders•• Known as laughing gas Known as laughing gas

AdvantagesAdvantages•• Safest anesthetic Safest anesthetic •• Non-flammableNon-flammable•• Non-irritatingNon-irritating•• Rapid induction nad rapid recoveryRapid induction nad rapid recovery•• Pronounced analgesic actionPronounced analgesic action•• Does not induce post-operative nausea and vomiting Does not induce post-operative nausea and vomiting •• Used in painful procedures like cleaning and changing burn woundsUsed in painful procedures like cleaning and changing burn wounds

DisadvantagesDisadvantages•• Not potent anestheticNot potent anesthetic•• Pre-anesthetic medication has to be givenPre-anesthetic medication has to be given•• Produce violent excitationProduce violent excitation•• HypoxiaHypoxia•• Increases cardiac irregularitiesIncreases cardiac irregularities

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CyclopropaneCyclopropane•• Colorless sweet smelling gasColorless sweet smelling gas•• Available in metal cylinders in compressed formAvailable in metal cylinders in compressed form•• Kept in cool placeKept in cool place

AdvantagesAdvantages•• Potent anesthetic Potent anesthetic •• Has fast inductionHas fast induction•• Rapid and smooth recovery Rapid and smooth recovery •• Maintains blood pressure and cardiac contracitilityMaintains blood pressure and cardiac contracitility•• Used in hemorrhagic agentUsed in hemorrhagic agent•• Does not produce irritation of respiratory passage Does not produce irritation of respiratory passage •• Good muscle relaxantGood muscle relaxant•• Produces quite breathingProduces quite breathing•• Supplies enough oxygenSupplies enough oxygen•• Does not produce visceral damageDoes not produce visceral damage

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DisadvantagesDisadvantages•• Induction is done carefullyInduction is done carefully

•• Produce cardiac irregularities Produce cardiac irregularities

•• Depresses respiratory centerDepresses respiratory center

•• Increases capillary oozing Increases capillary oozing

•• Anesthetic mixture of cyclopropane and oxygen is explosiveAnesthetic mixture of cyclopropane and oxygen is explosive

Non-volatile anestheticsNon-volatile anesthetics Thiopental sodium Thiopental sodium

•• Yellowish white hygroscopic powder Yellowish white hygroscopic powder •• Characteristic odour and bitter tasteCharacteristic odour and bitter taste•• Soluble in water Soluble in water •• Solution is freshly prepared before using it in injection formSolution is freshly prepared before using it in injection form•• Stored in sealed containersStored in sealed containers•• It is a derivative of barbituric acid and malonic esterIt is a derivative of barbituric acid and malonic ester•• Patient passes through the stages of hypnosis and deep sleep to Patient passes through the stages of hypnosis and deep sleep to

anesthesiaanesthesia•• First consciousness is lost and then reflex activity and finally First consciousness is lost and then reflex activity and finally

medullary centres are lost.medullary centres are lost.•• Used in minor operations such as fracture, dental surgerics, etcUsed in minor operations such as fracture, dental surgerics, etc•• Anti-convulsantAnti-convulsant

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AdvantagesAdvantages•• Non-explosiveNon-explosive•• Easy to administerEasy to administer•• Induction is rapid and without any unpleasant feelingInduction is rapid and without any unpleasant feeling•• Tendency of nausea and vomiting is very lessTendency of nausea and vomiting is very less•• Does not effect respirationDoes not effect respiration•• No post-anesthetic complicationsNo post-anesthetic complications

DisadvantagesDisadvantages•• Needs constant supervision to avoid overdostageNeeds constant supervision to avoid overdostage•• Depresses vasomotor centre and myocardiumDepresses vasomotor centre and myocardium•• Poor analgesicPoor analgesic•• Does not produce muscular relaxationDoes not produce muscular relaxation

Local anestheticsLocal anesthetics

Characteristics of local anestheticsCharacteristics of local anesthetics

•• Non-irritantNon-irritant

•• Should not be painfulShould not be painful

•• Low toxicityLow toxicity

•• StableStable

•• Should not damage nerve cellsShould not damage nerve cells

•• Sterilization of drugs should be easySterilization of drugs should be easy

•• Should not damage nerve cellsShould not damage nerve cells

The EstersThe Esters

CocaineCocaine•• It is alkaloid obtained from leaces of Erthroxylon CocaIt is alkaloid obtained from leaces of Erthroxylon Coca•• It is methyl benzoyl ester of Ecgonine which is a tropane derivativeIt is methyl benzoyl ester of Ecgonine which is a tropane derivative•• Basic in nature Basic in nature •• LevorotatoryLevorotatory•• White Crystalline powderWhite Crystalline powder•• Sparingly soluble in waterSparingly soluble in water•• Hygroscopic in natureHygroscopic in nature

AdvantagesAdvantages•• Useful in surgery of nose, throat and eyeUseful in surgery of nose, throat and eye•• Local anaesthtic action Local anaesthtic action •• Stimulates central nervous systemStimulates central nervous system

DisadvantagesDisadvantages•• Drug is addictionDrug is addiction•• Dilates pupilDilates pupil•• Raises blood pressureRaises blood pressure•• Produces euphoria and fatigueProduces euphoria and fatigue•• Poisonous in nature Poisonous in nature

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BenzocaineBenzocaine•• Ester derivative Ester derivative •• White crystalline powder White crystalline powder •• Stored in air tight containers Stored in air tight containers •• Light resistant containersLight resistant containers•• Soluble in waterSoluble in water•• Low toxicityLow toxicity•• Available under the name anestheticAvailable under the name anesthetic•• Useful as dustingUseful as dusting•• Used in throat lozengesUsed in throat lozenges•• Useful in relieving pain of gastric ulcerUseful in relieving pain of gastric ulcer•• Used in ointment form and is a surface anesthetic Used in ointment form and is a surface anesthetic

The amidesThe amides LignocaineLignocaine

•• Crystalline solidCrystalline solid•• Sparingly soluble in water Sparingly soluble in water •• Used as hydrochloric salt Used as hydrochloric salt •• Very stable Very stable •• Stored in room temperatureStored in room temperature•• Resistance to hydrolysisResistance to hydrolysis•• Used topically as surface anesthetic and ointment Used topically as surface anesthetic and ointment •• Available in injection form as spinal nerve block injectionsAvailable in injection form as spinal nerve block injections•• Quick onset of actionQuick onset of action•• Good analgesic agent Good analgesic agent •• Used for dental analgesiaUsed for dental analgesia•• Used in cardiac arrhythmiasUsed in cardiac arrhythmias•• Used for patients who are allergic to procaine Used for patients who are allergic to procaine •• Toxicity is similar to that of other local anestheticsToxicity is similar to that of other local anesthetics•• May cause drowsiness May cause drowsiness

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Anesthetics