Pediatric Dosage Calculation

Jordan and Logan Shaffer 11/08

How is Pediatric Dosage Calculation Different than Adults?

• There is no standard dose

• All doses are based on a recommended dosage based on:Body weight in kilograms (for this dosage test)

Body Surface Area

Begin by Converting to Kilograms

• All MD orders will be ordered as a dose per kg

• Convert the patient’s weight in lbs to kg by dividing the weight in lbs by 2.2

• Example:50 lbs divide by 2.2 = 22.7272727272727

Round to tenths place = 22.7 kg

Now you try!

1. Patients weight 48 lbs

How many kg does the patient weigh?

Patient weight 13.9 lbs

How many kg does the patient weigh?

Write your answer:

The MD order

The MD order can be written in several ways:

• In a daily total to be divided in equal doses

Ex: 30mg/kg/day equally divided in three doses

or• Per dose

Ex: 30mg/kg TID

Lets Try it!

Patients weight: 45 lbs

2. Give 30mg/kg/day equally divided in three doses

How many mg per dose? How much is the 24 hr drug total?

3. Give 30mg/kg TID

How many mg per dose? How much is the 24 hr drug total?

Write your answers

Is the dose safe?

• All pediatric dosages have a recommended range in the drug guide

• These ranges are typically based on a 24 hour total amount of a dosage in mg, mcg, gm, etc.

Is the order safe?

• A statement from the drug guide will be provided on the dosage test

Ex: The drug guide states the recommended safe dosage is 3-5 mg/kg/day to be given in 2 divided doses

Lets try it!

4. MD order Sporanox (itraconazole) 40 mg bidPatients weight 47 lbs

Drug guide recommends 3-5mg/kg/day q12 hrs

Is the dose safe?

Write your answer

Supply

• Pediatric medication is typically supplied in liquid form

• Some children can swallow pills or the medication may only come in tablet form

• Most of the dosage assessment questions will consist of medication in liquid form, few questions will be in tablet form

Remember….

• Supply is expressed as a dosage amount per a commonly used quantity

• Example 250mg/5ml

100mg/ml

50mcg/1ml

• This is different from the total amount of drug dosage in the bottle

Calculate Liquid Medication

Dose desired

Dose on hand X quantity in ml

= volume to be administered

Lets try it!

5. MD order is to give 75 mg

Supply is 250mg/5ml

Calculate the amount to administer

Write your answer

Read a label

• Some dosage questions will require you to read a drug label

Mixing directions:Add 30 ml of water

Mix VigorouslyDiscard after 5 days

Zantac

(ranitidine)

Oral suspension25mg/5ml

Lets try it!

6. Using the medication label supplied, how many milliliters should be administered per dose if the MD order is 100 mg po qd?

Write your answer

Intravenous

• Nothing new here….

Volume in ml x drop factor = gtt/min

Time in min

You are Ready!!! Lets put it all together

7. The physician orders Kantrex (kanamycin) oral suspension po 150 mg/kg/day in 2 divided doses.

Supply Kantrex 500mg/5ml.

Patients weight: 28 lbs

How many milliliters should be administered per dose?

Write your answer

8. The physician orders Prostigmin (neostigmine bromide) 8 mg q 4 hrs

The drug guide recommended dosage is 2-4 mg/kg/day in divided doses

Patients weight: 21 lbs

Is the physicians order safe?

Write your answer

Careful…some may have patients weight in kg already!

9. The physician orders Primacor (milrinone lactate) 50 mcg IM stat.

Supply: 0.2mg/ml

Patients weight: 12 kg.

How many milliliters should be administered per dose?

Write your answer

10. The physician orders Sustiva (efavirenz) 20mg/kg po q 12 hrs.Supply: Sustiva 50 mg tablets

Patients weight: 11 lbs

How many tablets are to be administered per dose?

Write your answer

11. The physician orders IV fluids as follows: Infuse 1000ml of 0. 45% normal saline solution in 10 hours IV.

• Calculate the flow rate when the drop factor is 10 drops per milliliters

Write your answer

12. An infusion of 700 ml of D5W was ordered to infuse at a rate of 25 gtt/min for 8 hours. The drop factor is 15 drops per milliliter.

• After 3 hours the patient had received 120 milliliters. The nurse decides the flow rate must be recalculated.

• Recalculate the flow rate____gtt/min

Write your answer

PRACTICE TEST TIME