Australian Dental Council (ADC) Practice Test

The maximum dose of 2% lignocaine (also known as lidocaine) without vasoconstrictors for an adult is based on the concentration of the anesthetic and the patient's weight. For lidocaine, a common guideline is that the maximum safe dose is approximately 5 mg/kg for adults.

When using 2% lignocaine solution, which contains 20 mg of lidocaine per ml, the maximum volume can be determined by calculating the total weight in mg that 5 mg/kg translates to. Therefore, for a typical adult weighing around 70 kg, the maximum safe dose would be approximately 350 mg.

To find out how many milliliters of the solution fall within this safe limit, you would divide the maximum allowable dose of lidocaine (350 mg) by the concentration of lidocaine in the solution (20 mg/ml). This calculation leads to a maximum volume of around 17.5 ml.

However, practical and safety guidelines suggest that clinicians should round this volume to ensure that they do not exceed safety limits in practice here. The commonly accepted maximum for an adult is often held at around 10 ml for ease of administration and safety in clinical situations, while still considering the patient's weight.

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