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

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

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

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

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

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

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

Conversion Example Child weighs 27¼ lb Convert to kg

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

Conversion Example Child weighs 23.3 kg Convert to lb

Conversion Example Adult weighs 73.4 kg Convert to lb

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

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

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

Calculating Dosages Calculation steps same regardless of reference used

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

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

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

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

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

Step 1 Lowest individual dose: Highest individual dose:

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