Pharmacy , Medication Calculations

Question

A physician orders lidocaine 1.5mg/kg to be given to a patient weighing 165 pounds. The pharmacy has available lidocaine injection in a 4% solution . How many milliliters of the lidocaine solution will be needed for the paitent?

4000mg/100ml = 112.5 mg / x >>>>> solving for x = 2.81mL needed

Answer 1

First we need to convert the patients weight (lbs) into kgs. 1 kg is equal to 2.2 lbs so we take 165 1lbs/2.2lbs

We then get 75 kgs from this. We multiply 1.5 kgs by 75 kgs to get the total dosage (1.5 x 75)=112.5 mg

Now a 4% solution of lidocaine is going to be 4g/100mL. We convert 4 grams into 4000 mg. Now we can cross multiply (4000mg/100mL) x (112.5mg/x). X is our answer. We cross multiply we get 4000x = 11250. Now divide 11250 by 4000 (11250/4000)=2.81 mL.

2.81 mL is our answer