Dosage of Local Anesthetic Agents – Types and Mode of Action

Local anesthetic agents should be given carefully because of the various adverse reactions to many Health conditions hence it is important to know the proper Dosage of Local Anesthetic Agent. It is very confusing if you are a Dental student or new to Practice to calculate the concentrations of Local Anesthetic agents. I how this post helps the students in their Exam Viva and also the Dental Practitioners in their Daily practice. Dosage of Local Anesthetic Agent is calculated based on the least amount of Local Anesthetic required to attain desired anesthesia and duration of pain control required for the procedure being performed.

There are many factors which are considered during determining the dosage of Local Anesthesia such as – Age, body weight, liver function, history of local anesthesia allergy etc. The type of Local Anesthesia being used should be altered depending on the dental procedure being performed and the duration of the Anesthesia being required.

The following points about LA Dosage are explained in the post below:

1. What is the Maximum dose of LA which can be used with Vasoconstrictor
2. What is the Maximum dose of LA which can be used without Vasoconstrictor
3. What is the Maximum dose of LA which can be used with Vasoconstrictor at 1:1,00,000 concentration
4. What is the Maximum dose of LA which can be used with Vasoconstrictor at 1: 50,000 concentration

Dosage Of Local Anesthesia:

1) Safety dose of 2% Lignocaine is 4.5mg/kg without a Vasoconstrictor

• Without a Vasoconstrictor 300 mg (maximum dose)

2) Safety dose of 2% Lignocaine is 7mg/kg with a Vasoconstrictor

• With a Vasoconstrictor – 500 mg (maximum dose)

3) As 1ml of 2% Lignocaine contains 20mg – Where the Maximum safety dose being 300 mg

• So 15 ml of Drug can be given safely

4) 1:1,00,000 concentration means 1 part of Adrenaline is 1,00,000 parts of Solution

• Safety Dose of Adrenaline for Dental Use in noraml patients is 0.2 mg – which means 20 ml of LA can be given to normal patients containing Adrenaline
• For cardiac Patients the safety dose of Adrenaline is 0.04mg – Which means 4ml of LA can be given to Patients with cardiac problems containing Adrenaline

5) If the concentration of LA is 1:50,000 – 10 ml of LA can be given safely

How to Calculate the Volume of Local Anesthesia to be administered:

The volume of LA agents is given in Milliliters or ml and to calculate the volume to be given it depends on the concentration of the agent being administered –

Example:

• 1% Lignocaine hydrochloride is 10mg of lignocaine hydrochloride per 1ml
• Maximum volume of 1% Lignocaine that can be administered to a patient weighing 10kg is – 45mg x 10mg/ml = 4.5ml
• (Note: As maximum dose of Lignocaine is 4.5mg per Kg – 4.5 mg x 10 kg – 45mg)

Types of Local Anesthetic Agents Used in Dentistry:

Lignocaine – Also called as Lidocaine Xylocaine etc. It is the most commonly used Local Anesthetic agent in Dentistry.

• Onset: Rapid
• Duration of Action: 120 (without Epinephrine), 240 minutes (with Epinephrine)
• Maximum Dose – 4.5mg/kg (without Epinephrine), 7mg/kg (with Epinephrine)

Mepivacaine:

• Onset: Rapid
• Duration of Action: 180 mins (without Epinephrine), 360 mins (with Epinephrine)
• Maximum Dose – 5mg/kg (without Epinephrine), 7mg/kg (with Epinephrine)

Bupivacaine:

• Onset: Slow
• Duration of Action: 240 mins (without Epinephrine), 8 hours (with Epinephrine)
• Maximum Dose – 2.5 mg/kg (without Epinephrine), 3 mg/kg (with Epinephrine)

Levobupivacaine:

• Onset: Medium
• Duration of Action: 180 mins (without Epinephrine), 360 mins (with Epinephrine)
• Maximum Dose – 2-3 mg/kg

Ropivacaine:

• Onset: Medium
• Duration of Action: 240 to 360 mins (without Epinephrine), 8 hrs to 12 hrs (with Epinephrine)
• Maximum Dose – 2 mg/kg or 400 mg in 12 hours

Procaine:

• Onset: Slow
• Duration of Action: 90 mins (without Epinephrine), 360 mins (with Epinephrine)
• Maximum Dose – 8mg/kg (without Epinephrine), 7.5mg/kg (with Epinephrine)

Chloroprocaine:

• Onset: Slow
• Duration of Action: 30 mins (without Epinephrine), 90 mins (with Epinephrine)
• Maximum Dose – 2.5mg/kg (without Epinephrine), 4mg/kg (with Epinephrine)

Etidocaine:

• Onset: Rapid
• Duration of Action: 240 mins (without Epinephrine), 480 mins (with Epinephrine)
• Maximum Dose – 2.5mg/kg (without Epinephrine), 4mg/kg (with Epinephrine)

Prilocaine:

• Onset: Medium
• Duration of Action: 90 mins (without Epinephrine), 360 mins (with Epinephrine)
• Maximum Dose – 5mg/kg (without Epinephrine), 7.5mg/kg (with Epinephrine)

Tetracaine:

• Onset: Slow
• Duration of Action: 180 mins (without Epinephrine), 600 mins (with Epinephrine)
• Maximum Dose – 1.5mg/kg (without Epinephrine), 2.5mg/kg (with Epinephrine)

To prevent toxicity to a patient undergoing dental surgery it is important to decide which type of Local Anesthetic Agent to be used depending on the various factors used to decide the dosage. It is important for the Dentist to have basic knowledge about the various types of LA agents and when and where to use them to prevent LA toxicity.