Classification of Anesthetic Agents

There are many different anesthetic agents available and the user may vary depending on the site of the procedure, type of anesthesia [local versus spinal] and duration of anesthesia sought.

In addition to this patient’s allergy profile needs to be taken into account.

Lidocaine is the most commonly used anesthetic and belongs to the amide group.

Bupivacaine is used where longer effects of anesthesia are required.

In case of allergy to lidocaine,  an ester-type anesthetic, such as procaine, can be substituted

Classification of Anesthetic Agents

Local anesthetics may be classified according to chemistry, duration of action or clinical uses. Another classification of anesthetic agents is for clinical use and differentiation. This divides them into agents with or without vasoconstrictor.

Classification of Anesthetic Agents According to Chemistry

Depending upon their chemical structure, the local anesthetics can be divided into esters, amides or naturally derived.

The names of local anesthetic have the suffix “caine”.

But the naturally derived local anesthetics not derived from cocaine have suffix -toxin in their names. These are neurotoxins. These bind to the extracellular side of sodium channels in contrast to cocaine produced local anesthetics which are intracellular in effect.

Ester local anesthetics are metabolized by pseudocholinesterase whereas amide anesthetics are metabolized in the liver.

Ester group

• Benzocaine
• Chloroprocaine
• Cocaine
• Cyclomethycaine
• Dimethocaine(Larocaine)
• Piperocaine
• Propoxycaine
• Procaine(Novocaine)
• Proparacaine
• Tetracaine(Amethocaine)

Amide group

• Articaine
• Bupivacaine
• Cinchocaine (Dibucaine)
• Etidocaine
• Levobupivacaine
• Lidocaine (Lignocaine)
• Mepivacaine
• Prilocaine
• Ropivacaine
• Trimecaine

Naturally derived

• Saxitoxin
• Neosaxitoxin
• Tetrodotoxin
• Menthol
• Eugenol
• Cocaine
• Spilanthol

According to Duration of action

Short Duration of Action

• Procaine

Medium Duration of Action

• Cocaine
• Lidocaine
• Mepivacaine
• Prilocaine

Long Duration of Action

• Tetracaine
• Bupivacaine
• Etidocaine
• Ropivacaine

According to Clinical Uses

Surface Anesthesia

• Tetracaine
• Lignocaine
• Cocaine
• Benzocaine

Infiltration Anesthesia & Field Block Anesthesia

• Lignocaine
• Procaine
• Bupivacaine

Nerve Block Anesthesia

• Procaine
• Lignocaine
• Bupivacaine
• Tetracaine
• Ropivacaine

Spinal Anesthesia

• Lignocaine
• Tetracaine
• Bupivacaine

Epidural Anesthesia

• Lignocaine
• Bupivacaine

Used In Ophthalmology

• Proparacaine

With or Without Vasoconstrictors

Vasoconstrictors are drugs that constrict vessels. For example epinephrine.

When an anesthetic agent is desired for a longer time, it is used with a vasoconstrictor. These are .commercially prepared mixed solutions available as different colored packing.

Vasoconstrictor, for the period it constricts vessels, hence temporarily reduces the rate at which the circulation removes the local anesthetic from the area of the injection.

Because the systemic drainage is at a lesser rate, the maximum doses of LAs when combined with a vasoconstrictor is higher compared to the same LA without any vasoconstrictor.

Lignocaine with epinephrine is a commonly used anesthetic agent with vasoconstrictor.