<prompt> Which of the following statement isare not true about Dibucaine:Shorter acting than tetracaineLonger acting than tetracaineMore potent than tetracaineMore potent than bupivacaine  <response>: Ans: A Shorter,,. DIBUCAINEDibucaine: Longest: acting local anesthetic, most potent most toxic- Ajay Yadov 2nd110DibucainefCin chocaine:!t is the most potent, most toxic longest acting LA It is used as a surface anaesthetic on less delicate mucous membrane anal canal. Use for spinal anaesthesia of long durartion has declined after the availability ofbupivacaine- KDT 6th358The dibucaine number is a measure of the qualitative activity of pseudocholinesterase and is the percentage of inhibition of the enzyme by the local anesthetic dibucaine. Normal individuals are homozygous for the wild type, and their dibucaine number is 80 because their plasma cholinesterase is 80 inhibited by dibucaine. Those who are homozygous for the atypical genes have a dibucaine number of 20 because of 20 inhibition Heterozygous individuals have a dibucaine number of 60 because of approximately 60 inhibition. The plasma cholinesterase level is a quantitative measure of this enzyme. Plasma cholinesterase should not be confused with cholinesterase activity, which is an assessment of erythrocyte or red blood cell cholinesterase. The combination of dibucaine number and plasma cholinesterase can differentiate genetic from nongenetic causes of prolonged apnea after the administration of succinylcholine-Millter 7th1095Atypical Pseudocholinesterase Ajay Yadav 2nd88 Incidence :1 in 3000.This can be diagnosed by Dibucaine numberDibucaine is a local anaesthetic which can inhibit 80 of normal enzyme 20 of abnormal enzyme. So normal dibucaine number in homozygous typical normal person is 70-80Sodium floride can be used in place of dibucaineFloride numberUsually apnoea is for 1 to 2 hrTable Ajay Yadav:Summary of properties of local AnestheticsDrugPotencyT12Duration of actionWithout adrenalineDuration of action With adrenalineMaximum safe dose mg kgCommentsEsters Procaine 15-30 minute30-90 minutes12 mgkg Chloroprocaine 15-25 minute30-90 minutes12 mgkgShortest actingCocaine 3 mgkgUsed for topicalAnesthesiaPotentvasoconstrictorTetracaine 2-3 hours3-5 hours3 mgkg AmidesLignocaineXyocaine 1.6 hrs45-60 minutes12-3 hours3 mgkg without adrenaline; 7 mgkg without adrenalineMost commonly used local anaestheticPrilocaine 45-60 minutes2-3 hours8 mgkgCan cause methaemoglobinemiaMepivacaine 45-60 minutes2-3 hours4.5 mgkg Etidocaine 2-3 hours3-5 hours4 mgkg Bupiva caine Sensoricaine, Mancaine 3.5 hrs2-3 hours3-5 hours2 mgkgVery commonly used local anaestheticRopivacaine 2-3 hours3-5 hours3 mgkgLess cardiotoxic than bupivacaineDibucaine 4 hrs2.5-3.5 hours3.5-5.5 hours1 mgkgLongest acting, most potent, most toxicProperty of local anaesthesia KDT 6th356DrugMax. safe dose mgDuration of nerve block minLidocaine30060-120Bupivacaine100180-360Tetracaine80180-480Dibucaine50180-600Drug used for spinor anaesthesia KDT 6th360DrugTotal dosemgDuration of action minLidocaine25-10060-90Bupivacaine10-2590-150Tetracaine5-1590-150Dibucaine2.5-10120-180 Type of Butyryl- cholinesteraseIncidenceDibucaine NumberResponse to SuccinylcholineHomozygous TypicalNormal70-80NormalHeterozygous Atypical148050-60Lengthened 50- 100Homozygous Atypical1320020-30Prolonged to 4-8 hrsButyrylchofinesterase Pseudocholinesterase Deficiency: Levels can be affected by liver disease, advanced age, malnutrition, pregnancy, bums, OCP, etc.Large decreases in butyrylcholinesterase causes only- moderate increase in duration of action of succinylcholineDibucaine NumberDibucaine inhibits normal enzyme to far greater extent that variant. Thus, if the dibucaine number is low i.e. the native enzyme is not inhibited by dibucaine, one should suspect or? abnormal variant of butyrylcholinesterase. 