Chapter 10
Dosage Problems for
Infants and Children
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Converting Ounces to Pounds
• 16 ounces = 1 lb
• An infant weighs 6 lbs 12 ounces
• Divide 12 ounces by 16 and get a decimal: 0.75
• Add the answer to the pounds to get the total pounds
• 6 lbs + 0.75 pound = 6.75 pounds
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Converting Pounds to Kilograms
• 2.2 lbs = 1 kg
• A child weighs 35 lb
• Divide 35 lbs by 2.2 and round answer off to the nearest hundredth: 15.91 kg
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Question
Is the following statement true or false?
An infant weighs 9 lbs. This is equal to 4.2 kg.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Answer
False
• 2.2 lbs = 1 kg
• A infant weighs 9 lb
• Divide 9 lbs by 2.2 and round answer off to the nearest hundredth: 4.09 kg
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Steps and Rule – mg/kg Body Weight
• Convert pounds to kilograms, dividing by 2.2
• Determine the safe dose range in milligrams per kilograms
• Decide whether the ordered dose is safe by comparing the order with the safe dose range listed in the reference
• Calculate the dose needed
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Sample Problem mg/kg Body Weight
• A child weighs 18 kg and has an order for Dilantin
(phenytoin sodium) 30 mg po every 8 hours. The recommended dosage is 5 mg/kg/day in two or three equally divided dosages. Is the dosage safe?
• Determine the safe dose range in milligrams per kilograms: 18 kg × 5 mg/kg/day = 90 mg day. The safe dosage for this child per day is 90 mg.
• Decide whether the ordered dose is safe by comparing the order with the safe dose range listed in the reference: Yes, this dosage is safe.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Steps and Rule – m 2 Medication Orders
• Find the BSA in m 2
• Determine the safe dose using a reference
• Decide whether the ordered dose is safe
• Calculate the dose needed
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Steps to Solving Parenteral Pediatric
Medications IVP
• Convert pounds to kilograms
• Determine the safe dose range in mg/kg using a drug reference
• Decide whether the ordered dose is safe by comparing the order with the safe dosage range listed in the reference
• Calculate the dose needed
• Check the reference for diluent and duration for administration
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Question
A child weighs 50.6 lbs and has an order for gentamicin 50 mg IVPB. The recommended dosage for a child is 6 to
7.5 mg/day divided every 8 hours.
Is the dosage ordered safe?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Answer
Yes, the dosage is safe.
• Convert pounds to kilograms: 50.6 lb = 23 kg
• Determine the safe dose range in mg/kg using a drug reference: 6 mg × 23 = 138 per day / 3 doses a day 46 mg/dose ---- 7.5 mg × 23 = 172.5 mg per day / 3 doses
= 57.5 mg/dose
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

General Guidelines for Continuous IV
Medication
• Continuous IV dosages are based on weight in kilograms
• Always use an infusion pump and/or volume control set
• Small bags of fluid used to prevent fluid overload
• Follow institutional requirements for continuous IV infusions
• Consult a pediatric text or drug reference to determine the safe dosage range
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins