LOCAL ANAESTHESIA (LA): AN OVERVIEW

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ABOUT AUTHORS:
Mayure Vijay Kumar*, V. Sravanthi
Maheshwara College of Pharmacy (B-Pharm Scholar)
Department of pharmacology,
Maheshwara College of Pharmacy, Chitkul (V), Isnapur “X” Road, Patancheru, Hyderabad, A.P.
mayurevijaykumar@gmail.com

ABSTRACT:
The anaesthetic agents are the drugs which causes anaesthesia-reversible loss sensation. It deals with the property of relieving the pain without eliminating sensation. These drugs are generally administered to facilitate surgery. It can be described by two main classes. General anaesthetic, which causes a reversible loss of consciousness, and local anaesthetics, which causes a reversible loss of sensation for a limited region of the body while maintaining consciousness. Here I explain about the Local anaesthetics agents that prevent transmission of nerve impulses without causing unconsciousness. They act by binding to fast sodium channels from within in an open state.
BACKGROUND: The purpose of this Review article is to summarize the Local anaesthetics agents, general mechanism, structures, therapeutic uses, adverse effects and also explains their properties.

INTRODUCTION:(General)
Cocaine is a naturally occurring compound indigenous to the Andes Mountains, West Indies, and Java. It was the first anaesthetic to be discovered and is the only naturally occurring Local anaesthetic; all others are synthetically derived. Cocaine was introduced in to Europe in the 1800s following its isolation from Coca beans. Sigmund Freud, the noted Austrian psychoanalyst, used cocaine on his patients and became addicted through self-experimentation.

In the latter half of the 1800s, interest in the drug became widespread, and many of cocaine’s pharmacologic actions and adverse effects were elucidated during this time. In the 1880s, Koller introduced cocaine to the field of ophthalmology, and Hall introduced it to dentistry. Halsted was the first to report the use of cocaine for nerve blocks in the US in 1885 and also became addicted to the drug through self-experimentation.

Procaine, the first synthetic derivative of cocaine, was developed in 1904. Lofgren later developed lidocaine, the most widely used cocaine derivative, during World War II in 1943.

GENERAL MECHANISM OF ACTION OF LOCAL ANAESTHETIC:

Table 1: Properties of local anaesthetics:

Drug	Onset	Duration	Tissue penetration	Plasma half-life(h)	Main unwanted effects	notes
Cocaine	Medium	Medium	Good	-1	CVS and CNS effects owing to block of amine uptake	Rarely used, only as spray for upper respiratory tract
Procaine	Medium	Short	Poor	<1	CNS: anxiety, Restlessness, shivering, depression. CVS: Bradycardia, and decrease cardiac output, vasodilatation,	The first synthetic agent No longer used
Lidocaine	Rapid	Medium	Good	-2	Less tendency to cause CNS effects	Used intra venously fortreating ventricular dysrythmias .
Tetracaine	Very slow	Long	Moderate	-1 as lidocaine	As lidocaine	Used mainly for spinal andcorneal anaesthesia.
Bupivacaine	Slow	Long	Moderate	-2	As lidocaine, but greater cardiotoxicity	Widely used causes less cardio toxicity(levobupivacaine)
Prilocaine	Medium	Medium	Moderate	-2	No vasodilator activity can cause methaemoglobinaemia	Widely used

Table 2: local anaesthetics:

The below list/table are the drugs belonging to local anaesthetics their therapeutic use, adverse effects and structures in pharmaceutical field:

CONCLUSION:
Understanding the pharmacology of local anaesthetics enables the anaesthetist to predict the potency, speed of onset, duration of action and safety of a specific drug in a given clinical situation, this maximises the opportunity for safe and effective use of local anaesthesia in a wide variety of contexts. The review here illustrates general mechanism, chemistry and therapeutic uses as well as side effects of the local anaesthetic agents including properties and their usage to the future aspects (anaesthetics) and make aware about the types and benefits of local anaesthetic agents.

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