If a patient weighs 120 lbs and has no specific medical condition, what is the maximum amount of cartridges of 2% lidocaine 1:100,000 that can be administered?

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To determine the maximum number of cartridges of 2% lidocaine 1:100,000 that can be safely administered to a patient weighing 120 lbs, it is essential to calculate the maximum dose of lidocaine based on body weight.

The maximum recommended dose of lidocaine is typically 5 mg/kg. First, we convert the patient's weight from pounds to kilograms, knowing that 1 kg is approximately 2.2 lbs. Therefore, 120 lbs converts to about 54.4 kg (120 lbs ÷ 2.2).

Then, we calculate the maximum safe dose in milligrams:

• Maximum dose = 5 mg/kg × 54.4 kg = 272 mg of lidocaine.

Next, we need to understand how much lidocaine is contained in each cartridge. A 2% solution means there are 20 mg of lidocaine per milliliter. Since most dental cartridges contain 1.8 ml, the amount of lidocaine in one cartridge of 2% lidocaine can be calculated as:

• 20 mg/ml × 1.8 ml = 36 mg of lidocaine per cartridge.

To determine how many cartridges can be administered safely, we divide the maximum allowable dose of lidocaine