1. Adult and Pediatric Dosages Based on Body Weight
Chapter 13
Adult and Pediatric Dosages Based on Body Weight

2. Body Weight
Major factor in calculating medication dosages for both children and adults
Most important determiner of dosages for neonates and infants

3. Body Weight
Although health care provider prescribes medication and dosage, nurse’s responsibility to check prescription to ensure safety for client

4. Body Weight
Pediatric-safe dosage ranges usually based on kg of body weight
Adult dosages based on either pounds (lb) or kg of body weight
Most often based on kg

5. Converting lb to kg
Body weight in kg always smaller than body weight in lb
Due to conversion being made by dividing body weight in pounds by 2.2

6. Converting lb to kg Fractional lb converted to nearest quarter-pound
Fractional kg weights rounded to nearest tenth

7. Conversion Example
Child weighs 21 lb 12 ounces (oz)
Convert to kg

8. Conversion Example
Child weighs 27¼ lb
Convert to kg

9. Converting kg to lb Weight in lb more than twice that of weight in kg
To convert, multiply kg by 2.2

10. Conversion Example
Child weighs 23.3 kg
Convert to lb

11. Conversion Example
Adult weighs 73.4 kg
Convert to lb

12. Calculating Dosages from Drug Label Information
Information needed to calculate dosages from body weight found on actual drug label or drug package insert

13. Calculating Dosages from Drug Literature/References
Hospital formulary
Hospital pharmacist
Published medication references
e.g., drug handbooks, etc.

14. Nursing References Most helpful include:
Nursing implications about each medication
Specific information on drug form
e.g., oral, IV

15. Calculating Dosages
Calculation steps same regardless of reference used

16. Before Beginning Read carefully
Safe/Recommended dosage ranges may be based on total daily dose or individual dose

17. Daily Dosage Ranges
If range based on daily dose, divide daily dose by number of doses client receives per day

18. Two-Step Calculation Process
Client’s weight placed into range formula to determine safe/recommended dosage
Compare result to prescribed dosage to determine if prescribed dosage safe/recommended for this client

19. Two-Step Calculation Process
Discrepancies in dosages much more significant if small number of mg prescribed
Younger, older, or more compromised by illness the client, more critical the discrepancy

20. Calculation Example
Prescription for 125 mg of medication every 8 hours
Child weighs 18.2 kg
Safe/Recommended range for medication 20 to 40 mg/kg/day
Determine if prescribed dose within safe/ recommended range

21. Step 1
Lowest individual dose:
Highest individual dose:

22. Step 2
Child weighing 18.2 kg can receive between 121 mg and 243 mg per dose
Prescription for 125 mg dose within safe/ recommended range