DosageHelp.com Helping Nursing Students Prepare for Medication Exams By Explaining Dosage Calculations

# Dosage By Weight Questions

Given the weight of a patient and a dosage specified in terms of weight, calculate the necessary dosage. These problems are a type of pediatric dosage calculations.

Formula:
 Weight in Kg * Dosage Per Kg =  Y (Required Dosage)

Example: A doctor orders 200 mg of Rocephin to be taken by a 15.4 lb infant every 8 hours. The medication label shows that 75-150 mg/kg per day is the appropriate dosage range. Is this doctor's order within the desired range?
 Weight in Kg * Dosage Per Kg =  Y (Required Dosage)
Convert 15.4 lb to kg.
• lb → kg    ( ÷ by 2.2 )
• 15.4 lb ÷ 2.2 = 7 kg
 7 kg * 75 mg/kg =  525 mg (Minimum Desired Dosage)
 7 kg * 150 mg/kg =  1,050 mg (Maximum Desired Dosage)
24 hours in one day and the medication is ordered every 8 hours.
• 24 hrs / 8 hrs = 3 times per day doctor ordered medication
• 200 * 3 = 600 mg ordered per day
• 600 mg is within the desired range of 525-1,050 mg
Yes doctor has ordered a dosage within the desired range.

Example: Solumedrol 1.5 mg/kg is ordered for a child weighing 74.8 lb. Solumedrol is available as 125 mg / 2mL. How many mL must the nurse administer?
 Weight in Kg * Dosage Per Kg =  Y (Required Dosage)
Convert 74.8 lb to kg.
• lb → kg    ( ÷ by 2.2 )
• 74.8 lb ÷ 2.2 = 34 kg
 34 kg * 1.5 mg/kg =  51 mg
 Ordered Have
x Volume Per Have  =  Y (Liquid Required)
 51 mg 125 mg
x 2 mL  =  0.82 mL

Home Dosage Question Steps Unit Conversion Mass for Mass Mass/Liquid For Liquid IV Terms & Abbreviations Amount in IV Fluid Volume/Time - IV mL Rate Volume/Time - IV Drop Rate Fluid Maintenance Dosage By Weight Mass/Time - IV mL Rate Practice Questions Question of the Day Tell a Friend Print a Flyer