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 KgWgt (kg) | x | Dosage Per KgDose/kg | = | Y (Required Dosage)Y (Dose) |
Example: A doctor orders 200 mg of Fictocef 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 KgWgt (kg) | x | Dosage Per KgDose/kg | = | Y (Required Dosage)Y (Dose) |
- lb → kg ( ÷ by 2.2 )
- 15.4 lb ÷ 2.2 = 7 kg
| 7 kg | x | 75 mg/kg | = | 525 mg (Minimum DesiredMin Dosage) |
| 7 kg | x | 150 mg/kg | = | 1,050 mg (Maximum DesiredMax Dosage) |
- 24 hrs / 8 hrs = 3 times per day
- 200 * 3 = 600 mg ordered per day
- 600 mg is within the range of 525-1050 mg
Example: Placebosol 1.5 mg/kg is ordered for a child weighing 74.8 lb. Placebosol is available as 125 mg / 2mL. How many mL must the nurse administer?
| Weight in KgWgt (kg) | x | Dosage Per KgDose/kg | = | Y (Required Dosage)Y (Dose) |
- lb → kg ( ÷ by 2.2 )
- 74.8 lb ÷ 2.2 = 34 kg
| 34 kg | x | 1.5 mg/kg | = | 51 mg |
- This is now an ordinary Mass/Liquid For Liquid Question. 51 mg is ordered and the medication is available as 125 mg / 2 mL.
|
x | Volume Per HaveVol/Have | = | Y (Liquid Required)Y (Liquid) |
|
x | 2 mL | = | 0.82 mL |