Local Anaesthetic.

Local Ansthetics

1. Local Anaesthetic Prepared by, Ms. KOTE R. B. Lecturer PRES’s Institute of Pharmacy Loni .

2. Local Anaesthetic Local anaesthetics are agents that produce reversible loss of pain sensation in localised area wherever applied or injected , by blocking conduction of nerve impulses, without affecting degree of consciousness. Eg. Lignocaine, Procaine, Amethocaine ,Cocaine etc These are used in local sugery like where complete loss of consciousness is not needed

3. Classification Naturally occurring- e.g. Cocaine Synthetic compounds – a. Nitrogen containing- Lignocaine, Procaine, Amethocaine , Benzocaine b. Non- Nitrogenous – Benzyl alcohol, propanediol. Miscellaneous – Clove oil

4. Advantages of LA Safer than general anaesthetic Persons with cardiac Pulmonary renal diseases diabetes face less complication No loss of consciousness Produces good analgesic and muscle relaxant property Useful when during surgical procedure patients cooperation is needed.

5. Ideal properties of Local Anaesthetic Non irritant - Non Sensitizing , Non allergic Reversible- Local anaesthesia induced should be reversible has rapidly reversible Induce quick Local anesthesia Stable on storage Should produce prolonged effect till operative Procedure is not complete Should not be habit forming

6. Mechanism of action of local anesthetics Local anesthetics act on outer part cell membrane Local anesthetics are known to reduce the membrane permeability changes to Na+ & K + It is believed that Ca ++ ions controls passage of Na+ across the cell membrane. LA competitively prevent binding of Ca ++ to membrane& thus interferes with transport of Na+ across cell membrane . The net result of all above series of action agent results in anaesthesia .

7. Techniques of application of LA 1. Topical/ Surface Anaesthesia- In the form of ointment, creams or powder Application- To reduce pain & itching of ulcers To anaesthetized corneal surface, mucosa of mouth, nose pharynx, larynx Eg. 2-5 % lignocaine, Amethocaine

8. 2. Infiltration Anaesthesia – Anaesthesia produced by injecting anaesthetic agent through out area to be anaesthetized. In this nerve endings are anaesthetized by their exposure to drugs. Application- Minor surgery like removal of Cyst. Eg . Lignocaine Procaine

9. 3 . Nerve block Anaesthetic –  In this technique either anaesthetic agent is injected in surrounding area of that part which is to be operated or deposited close to the mixed nerves like radial ulnar , palantine etc.  Accordingly it is define as field block or nerve block anaesthesia Application- Tooth extraction Ophthalmology Fracture setting Eg . Lignocaine Procaine

10. 4. Spinal Anaesthetic- L 2-L3 or L3-4 Spinal anaesthesia in this technique the drug is injected into subarachnoid space. After administration agent reaches to the roots of spinal nerves at dorsal root of ganglia. The drug is injected at the site to block roots of those nerves which innervate the area to be operated. During administration position of patient plays a vital role in restricting the anaesthesia to desired level. Duration of spinal anaesthesia can be increased by addition of 0.2 ml of 1: 1000 solution

11. Application- In obstetrics In gynaecological surgery

12. lignocaine lignocaine it is commonly used local anaesthetic and more stable it has quick onset of action and high degree of penetration. It is widely used for- Infiltration anaesthesia (0.25 to 5 % soln) Intravenous Nerve block anaesthesia. (1 to 2 % soln) Epidural anaesthesia

13. procaine It is a non-irritant local anaesthetic. It is effective rapidly when administered parenterally it is not effective as a topical anaesthetic Its duration of action is very short and can be prolonged by administration of adrenaline . Preparations- 1-2%- central block anaesthesia 50-20 mg intrathecally- Spinal anaesthesia 2% solution- Infiltration anaesthesia

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