Amide Local

Anaesthatic

Nur Amalina bt. Aminuddin Baki60

Introduction • Amide link: covalent chemical bond

Amide Local Anaesthetics

Longer acting • Bupivacaine • Ropivacaine • Etidocaine • Dibucaine

Intermediate acting • Lignocaine • Mepivacaine• Prilocaine

Bupivacaine

Ropivacaine • Intermediate onset• Compared to bupivacaine – Less potent– less cardiotoxic– Similar action duration– More motor sparing

• For infiltration, epidural and regional anaesthesia • Continuous epidural use for post-operative and

labour pain relief

Etidocaine• Fast onset, analgesia 2-3 times longer• For infiltration and nerve block anaesthesia• Peridural analgesia ( more motor blockade and

abdominal muscle relaxation)• Limited use in vaginal delivery ( block expulsion)• X spinal anaesthesia – May produce convulsion

• Similar cardiotoxic with bupivacaine

Dibucaine / Cinchocaine • Very potent, longest acting, slow onset, rarely

used • For surface anaesthesia in anal canal and

rectum and spinal anaesthesia of long duration

• More toxic than bupivacaine• Pseudocholinesterase inhibitor

Intermediate Acting

Lignocaine / Lidocaine / Xylocaine

• Most widely used ,multipurpose, fast, • Max. effect : 2-5 minutes, lasts for 30-45 min• Useful for all types of blocks• Available as: 4% topical solution, 2% jelly, 5% ointment,

1%, 2% injection ,5% spinal anaesthesia and 10% spray• Formulation with epinephrine:– Delay absorption ,prolong action,reduce toxicity

• Intratechal/ epidural of lidocaine with opioid analgesic (SYNERGISTIC)

• Cause – (low) drowsiness– (increased) dizziness, paraesthesia, euphoria – (high)confusion, vertigo, tinnitus, nausea

• Precipitate seizure, respiratory depression, coma– Treatment: Diazepam/ Thiopental

• Other uses: – IV : ventricular arrythmia during MI

• Propanolol impair clearance, increasing toxicity

Mepivacaine • Compared to lidocaine :– More rapid onset – Longer action – Not effective as topical

• Similar toxicity to lidocaine

Prilocaine • Intermediate onset and duration• Poor VSD • Cause CNS toxicity – Restricted to dental procedure (infiltration, nerve

block )• Used in eutectic mixture• Similar lidocaine toxicity except:– Orthotoluidine cause neonatal methaemoglobinaemia– IV methyl blue

Eutectic Mixture• Lignocaine + Prilocaine• Preparation for anaesthesia of intacted skin• Low melting point of mixture penetrate

intact skin• Dermal anaesthesia during venesection, skin

graft, IV cannulation • Apply an hour before procedure

Conclusion Ester• Poor penetrability • Short duration • Hydrolysed by plasma and

liver esterases• Hypersensitivity common

Amide • Good penetrability• Longer duration • Degraded by hepatic

microsome• Rare hypersensitivity

Referance • HL Sharma and KK Sharma, Principles of

Pharmacology,2nd edition, 2012.• Padmaja Udaykumar, Textbook of Medical

Pharmacology, 2nd edition, 2010.