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BACKGROUND
Local anaesthesia is a technique to create loss of sensation in specific region of the body.1 Usually they are used in minor surgeries, dental procedures, cesarean section with reduced pain and distress. This technique is safer and superior to general anaesthesia.2
Local anaesthetic drugs produce reversible effect and a loss of nociception. When these drugs are used on specific nerve pathways they show effects such as analgesia and paralysis. Local anaesthetics differ in their pharmacological properties and are used in various techniques such as surface (topical) anaesthesia, infiltration, epidural block, plexus block and spinal anaesthesia.2
The aim of the present study is to determine the activity and tolerability of new local anaesthetics after surface anaesthesia on the cornea of rabbits.
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REQUIREMENTS
Animals required:
Albino rabbits of either sex weighing 2.5-3 Kg
Drugs:
Lignocaine 0.2%, test drug (0.05% and 0.1%)
Instruments used:
1 ml syringe (22 guage needle)
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PROCEDURE
Place the Albino rats in rabbit holding cages. Trim Both the upper and lower eyelashes carefully. Held open the conjuctival sac of one eye, to form a pouch. Instill 0.5 ml of test solution for 30 seconds. Then repeat the same procedure, so that finally 1.0 ml of test is instilled within 1 minute. Similarly instill 1 ml of standard drug (lignocaine) within 1 minute to the other eye. Test the corneal reflexes in both the eyes for every 5 minutes with wet cotton plug. Start the test within 5 minutes after application of the drug and repeat the same every 5 minutes till anaesthesia disappears and corneal reflex reappears again.
OBSERVATION
|
Drug |
Onset of surface anaesthesia (in min) |
Duration of surface anaesthesia (in min) |
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|
Right eye |
Left eye |
Right eye |
Left eye |
|
|
Lignocaine (0.2%) |
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Test drug (0.05%) |
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Test drug (0.1%) |
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CONCLUSION
Effective local anaesthetic ceases the corneal reflex produced by one touch of the cornea. Onset and duration of anaesthesia determines the effect of local anaesthetic.
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REFERENCES
- William A, Catterall A, Kenneth M. Local Anesthetics. In: Laurence Bruton L,Goodman and Gilmans The Pharmacological Basis of Therapeutics, 12 th ed. New Delhi: Mc Graw Hill Medical; 2011: 564.
- Local anesthesia. Available at: https://en.wikipedia.org/wiki/Local_anesthesia. Accessed on 17 October 2017.
- Vogel GH. Surface anaesthesia on the cornea of rabbits. Drug Discovery and evaluation-Pharmacological assays. 2nd edition. Newyork: Springer-Verlag; 2002: 655-656.
