# Need to determine dose based on weight.

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• Has 8 years experience.

Can someone help me do 1 problem so I can model it for similar problems of this kind. I am not sure what to do. Please step by step.

1. Order: Amoxicillin suspension 40 mg/kg/day in 3 divided doses. Supply: bottle labeled 125 mg/5ml. Childs weight is 15 kg. What is the quantity to administer? _______ml.

Do I do 5/125 = x/600. I got the 600 by multiplying 15kg by 40 mg. ??? I got 24 ml for the day and then divided into 3 doses its 8ml. Is that correct?

Can anyone give me a formula that can help me determine the answer. Thanks in advance to anyone who chooses to help me with this.

D

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Yup that's what I got. Good Job!!!

266 Posts

Specializes in labor & delivery. Has 7 years experience.

I got the same thing-8 ml per dose. The way I would do it is:

15 kg x 40mg = 600 mg

600 mg per dose / 3 doses =200 mg

125 mg:5 ml = 200 mg:X ml--ratio problem-- multiply inside numbers 5x200=1000 divide by remaining number 125 = 8ml

Outside numbers multiplied should equal inside numbers multiplied

Hope I explained it ok. I can show it easier than typing it out. This is how I learned.

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Specializes in med/surg, telemetry, IV therapy, mgmt. Has 40 years experience.

Order: Amoxicillin suspension 40 mg/kg/day in 3 divided doses.

Supply: bottle labeled 125 mg/5ml. Childs weight is 15 kg. What is the quantity to administer? _______ml.

By Dimensional Analysis:
40 mg/kg
(dose desired)
x 15 kg
(child's weight)
/3
(number of doses per day)
x 5 mL/125 mg
(dose on hand)
=
8 mL