What is the effect of injecting 2 milliliters (mL) of lidocaine (0.1% solution)?

From the Guidelines

If 2 ml of lidocaine 0.1% is injected, you are administering 2 mg of lidocaine, which is well below the recommended maximum safe dose of 4.5 mg/kg for adults without epinephrine, as suggested by guidelines for the use of local anesthesia in office-based dermatologic surgery 1. This calculation is derived from the concentration of the solution, where 0.1% means 0.1 grams of lidocaine per 100 ml of solution, which equals 1 mg/ml. Some key points to consider when using lidocaine for local anesthesia include:

• The maximum safe dose of local infiltrated anesthesia is unknown, but guidelines recommend no more than 4.5 mg/kg of lidocaine and 7.0 mg/kg of lidocaine with epinephrine for adults in a single treatment 1.
• For children, the recommended maximum dose is lower, at 1.5-2.0 mg/kg of lidocaine and 3.0-4.5 mg/kg of lidocaine with epinephrine 1.
• The onset of action for lidocaine is usually within 2-5 minutes, and the duration of anesthesia with this concentration would typically last about 30-60 minutes, though this varies based on the vascularity of the injection site and individual patient factors.
• Infiltrative anesthesia may be combined with other forms of local anesthesia for larger or more complex cutaneous procedures, such as full-face ablative laser resurfacing or follicular unit hair transplantation 1. Given the low dose of 2 mg of lidocaine, it is likely safe for minor local anesthesia procedures, but it is essential to consider individual patient factors and the specific procedure being performed to ensure the best possible outcome in terms of morbidity, mortality, and quality of life.

From the FDA Drug Label

The onset of anesthesia, the duration of anesthesia and the degree of muscular relaxation are proportional to the volume and concentration (ie, total dose) of local anesthetic used Thus, an increase in volume and concentration of Lidocaine HCl Injection will decrease the onset of anesthesia, prolong the duration of anesthesia, provide a greater degree of muscular relaxation and increase the segmental spread of anesthesia

The answer to the question of what happens when 2 ml of lidocaine 0.1% is injected is that it will produce some degree of local anesthesia.

• The onset of anesthesia will be relatively fast.
• The duration of anesthesia will be relatively short.
• The degree of muscular relaxation will be relatively small.
• The segmental spread of anesthesia will be relatively limited. 2

From the Research

Lidocaine Administration

• The administration of 2 ml of lidocaine 0.1% is a relatively small dose, and its effects would depend on various factors such as the location of injection, individual tolerance, and the presence of other medications.
• According to the study 3, the tissue distribution of lidocaine after injection can vary, with higher concentrations found in organs such as the kidney and liver, and lower concentrations in skeletal muscle and adipose tissue.
• The study 4 describes the use of limited dilute lidocaine anesthesia in a cellulite reduction procedure, where a mean delivered anesthesia volume of 357.2 ml was used, which is significantly higher than the 2 ml dose in question.

Safety and Efficacy

• Local anesthetics, including lidocaine, have an impressive history of efficacy and safety in medical practice, with adverse effects being infrequent 5.
• However, the study 3 highlights the importance of careful administration, as accidental overdoses can occur due to confusion between prepackaged dosage forms.
• The study 6 notes that local anesthetics are relatively safe if administered correctly, but excessive doses and accidental intravenous administration can lead to systemic toxicity.

Comparison with Other Studies

• The study 7 compares the pain visual analog scale (VAS) scores of local anesthesia using lidocaine with and without sodium bicarbonate, finding that buffered lidocaine reduces anesthetic pain effectively.
• While this study does not directly address the administration of 2 ml of lidocaine 0.1%, it suggests that the formulation and administration of local anesthetics can impact their efficacy and safety.