NABP NAPLEX Exam - Topic 1 Question 31 Discussion

If 40mg of amoxicillin are needed per kg of body weight, then the dose of amoxicillin is 40mg multiplied by the

patient's body weight. This patient weighs 18 lbs, based on the conversion of 2.2 lbs = 1 kg, the patient weighs

8.2 kg. 40 mg multiplied by 8.2 kg is equal to 328 mg, this is one dose of amoxicillin. If the amoxicillin comes in 250 mg/5 mL, then it needs to be determined how many mLs it will take to get 328 mg of amoxicillin. In order to do this 328 mg needs to be divided by 250 mg to get a ratio. This comes out to be 1.312. This ratio can be multiplied by the number of mLs it takes to make up 250 mg, which is 5 mLs. 1.312 multiplied by 5 mLs is 6.56 mL, this is how many mLs it will take to have 328 mg. This volume is for 1 single dose of amoxicillin. The patient is receiving 2 doses per day and for a total of 10 days, this means the patient will be receiving 20

doses. 20 doses multiplied by 6.56 mL doses equals the total volume the patient will be receiving, which is

131.2 mL.