JAN BAZNER-CHANDLER RN, MSN, CNS, CPNP BOWDEN TEXT BOOK CHAPTER 9 Pediatric Pharmacology.

JAN BAZNER-CHANDLERRN, MSN, CNS, CPNP

BOWDEN TEXT BOOK CHAPTER 9

Pediatric Pharmacology

Developmental Considerations

• Pharmacokinetics – Absorption– Distribution– Metabolism– Elimination

• Pharmacodynamics: how drug produces physiologic and biochemical changes

Absorption

Gastrointestinal absorption Gastric pH is high in neonate Intestinal motility (transit time) is decreased in

neonates and increased in older infant and children Bile acid pool and biliary function is diminished in

neonates

Absorption of Drugs

Rectal Intramuscular- varies Topical / dermal – related to skin hydrationIntraocular – thin membranes can cause

systemic effects

Distribution

Neonates have a higher proportion of total body water – related to water solubility of drug

Lower portion of body fat – lower doses of lipophilic drugs Digoxin: drug books with have different dosing for the

neonates, infant and children

Digoxin Example

IV children > 10 years (digitalizing dose): 8 to 12 mcg/kg given as 50% of the dose initially and ¼ of initial dose each of 2 subsequent doses at 6-12 hour intervals.

IV infants 1-24 months (digitalizing dose): 30 to 50 mcg/kg given as 50% of initial dose and ¼ of initial dose in each 2 subsequent doses at 6-12 hour intervals.

Davis Drug Guide

Digitalizing Dose

What does this mean?

Distribution Continued

Protein concentration at birth is 80% of adult values

Fetal albumin has limited drug binding ability High potential for toxicity

Immature blood-brain barrier Drug to treat neonatal sepsis will penetrate the brain Drugs can accumulate in the brain tissue

Metabolism

Newborn enzymatic microsomal system is less effective

Liver maturation varies

Elimination

Glomerular filtration and tubular secretion are reduced at birth

Gradual increase in renal function to adult level (about 1-2 years)

Nursing Responsibilities

Six Rights

Right medicationRight doseRight patientRight routeRight timeRight approach

Right Dose

• Drug dose calculated on weight in kilograms or BSA

• Adult dosages used in children who weigh more than 50 kilograms

• Double-check math calculations on all medication given

• BSA is the most accurate way to calculate dosages – Used in calculating chemotherapy– Neonates– ICU

Dispensing Correct Dose

Many drugs come in multi-dose containers Keflex 250 mg / 5 mL Amoxicillin 125 mg / 5 mL Acetaminophen comes in various concentration: 80

mg / 0.8 mL , 120 mg / 5 mL , 250 mg / 5 mL

Right Patient

Identification by 2 sources All children need identification wristband Two person identification (parent / nurse) All mediation taken into room should be labeled with

child’s name, name of drug, and dose MAR

Is the mediation appropriate for the patient?

Right Route / Time

Medications can be ordered po, sub-q, IM, IVMedications should be administered within ½

hour before or ½ hour after prescribed time. Problem if multiple intravenous medications ordered

to be given at the same time

Developmental Considerations

Infant Administer medication before the infant feeds Offer med in small amount of formula or cereal / fruit Give via spoon or syringe Parent may give but nurse must be in the room and

observe medication being given

Developmental Considerations

• Toddler– Simple explanation – Small cup or spoon (syringe may be seen as a “shot”)– Ask parent how child takes medication– May need to restrain in lap and offer small amounts

while holding the cheeks together until child swallows the med

– If giving injection – have parent or another nurse assist

Conversions you need to remember

1 teaspoon = 5 mL 1 tablespoon = 15 mL 1 ounce = 30 mL 1 gram (g) = 1000 milligrams (mg)1 milligram (mg) = 1000 micrograms (mcg)1 liter (L) = 1000 milliliters (mL)

grains (gr) to milligrams (mg)

gr 1 = 60 mggr ¾ = 45 mggr ½ = 30 mggr ¼ = 15 mg

Measuring cup

How many mL in 4 teaspoons?

Calculations

Pounds to kilograms Safe DosingHow to calculate medication dose using

ration / proportionIV medications24 hour fluid calculationsNaso-gastric drainage replacement

Pounds to Kilograms

• Pounds to kilograms = pounds

2.22.2

Nursing Alert:Nursing Alert:

In pediatrics you need to carry out to the In pediatrics you need to carry out to the hundredths (hundredths (do not rounddo not round))

Kilogram Example

20 pounds 5 ouncesFirst need to convert 5 ounces to a fraction of

a pound 5 divided by 16 = 0.31

20.31 pounds divided by 2.2 = 9.23 kilograms

Note medication would be calculated based on 9.23 kilograms. DO NOT ROUND

Pounds to kilograms

If a child weights 6 lbs 6 ounces what is the weight in kg?

6 ounces = 0.37 pounds 16 ounces

6.37 pounds divided by 2.2 kg = 2.89 kg

Medication dosage

For a dosage of medication to be safe, it must fall within the safe range as listed in a Drug Handbook, PDR or other reliable drug reference.

Safe Medication Dose

Calculate daily dose ordered (Physician orders)

Calculate the low and high parameters of safe range (from drug book)

Compare the patient’s daily dose to see if it falls within the safe range.

Calculation

A child is 2 years and weighs 36 lbs Physician order: Amoxicillin 215 mg po tid for

a bilateral otitis media (ear infection)

First you would need to change 36 lbs to kg

36 divided by 2.2

Patient weight in kg = 16.36 kg

Calculating Safe Range

Davis drug guide: PO (children) < 40 kg: Amoxacillin 6.7 to 13.3 mg / kg q 8 hours.

(low range)16.36 x 6.7 = 109.6 mg q 8hours

(high range)16.36 x 13.3 = 217.5 mg q 8 hours

Safe Range

109.6 mg to 217.5 mg of Amoxicillin Q 8 hours.

Is the 215 mg dose ordered by the MD safe? Yes (it falls within the safe range)

How much medication do you give?

Amoxicillin Suspension comes: 250 mg per 5 mL you want to give 215

mg

250 mg 215 mg 5 ml = x ml 1075 250x Give 4.3 mL po every 8 hours

Nursing Alert

Read the medication ranges carefully: dosing can be for:

dose range for 24 hours

dose range for q 8 hours

dose range for q 12 hours

Fluid Control

Crucial in the pediatric populationUnits often have policies that children under

a certain age are on a fluid control pump.

Fluid overload

Know what the IV rate is.Hourly recording of IV fluid intake.Don’t try and catch up on fluids.Calculate fluids used to administer IV

medications into the hourly fluids amount

Daily Fluid Needs

Fluid needs should be calculated on every patient to assure that the infant / child is receiving the correct amount of fluids.

Standard formula for pediatrics needs to be memorized.

Maintenance Fluid Requirement

Up to 10 kg 100 mL / kg/ 24 hours

11 to 20 kg 1000 mL + 50 mL / kg / 24 hours

Greater than 20 kg 1500 mL + 20 mL / kg / 24 hours

Bowden text page 740

Fluid Calculations

Since children are in the hospital for various illnesses they will often have increased fluid needs: dehydration, fever, vomiting, diarrhea, inability to take po fluids.

24 hour fluid calculations may be 1 ½ to 2 times maintenance.

Fluid Calculation

7.27 kilograms

100 mL x 7.27 kg = 727 mL

727 mL / 24 hours or 30 mL per hour

Fluid Calculation Problems

9 pound infant9 pounds = 4.09 kg (always calculate to

100th)4.09 x 100 mL = 409 mL / 24 hours 0r 17

mL / hour

1 ½ times maintenance = 1.5 x 409 = 613 mL / 24 hour or 25 mL / hour

Fluid Calculation

• 36 pound child• 36 pound = 16.36 kg• 10 kg x 100 mL = 1000 mL• 6.36 kg x 50 mL = 318 mL• 1318 mL / 24 hours or 55 mL / hour

• 1 ½ times maintenance = 1.5 x 1318 = 1977 mL / 24 hours or 82 mL / hour

Fluid Calculations

52 pounds52 pounds = 23.63 kg100 mL x 10 = 1000 mL50 mL x 10 = 500 mL20 mL x 3.63 = 72 mLTotal fluids = 1000 + 500 + 72 = 1572 mL /

24 hours or 65 mL / hour

1 ½ times maintenance = 1.5 x 1572 = 2358 mL / 24 hours or 98 mL / hour

Fluid Calculation

64 pound childConvert pounds to kilograms = 29.09 kgFluid calculations:

100 mL x 10 kg = 1000 mL 50 ml x 10 kg = 500 mL 20 ml x 9.09 kg = 181 mL

1681 mL / 24 hours or 70 mL / hour

IV Medications

Key concepts

Time over which a medication should be administered is critical information

Minimal dilution (end concentration of medication) is important for medications such as aminoglycosides).

Therapeutic blood levels

Buretrol or Volume Control Chamber

Total of medication in chamber + 20 ml IV fluidneeded to flush the medication.Page 316 Bowden text

IV Buretrol

A buretrol or volutrol is an inline receptacle between the client’s IV catheter set and the bag of fluids.

Capacity is 120 to 150 mLRationale: the nurse can fill the buretrol to a

certain level and if the IV pump malfunctions, only the volume in the buretrol will flow to the client.

Nursing Alert

• If the IV medication is not “flushed” with 15 to 20 mL of fluids the medication will still be in the line and could be a problem– If IV rate is KO (5-10 mL per hour) the medication in

the tubing would take 2 to 4 hours to get to the patient

– If you are giving two or more IV medications the drugs could be mixed in the tubing if the appropriate flush is not done

– * THE MD ORDERS WILL NEVER INCLUDE THE FLUSH IN THE ORDER

Nursing Alert

Include the extra fluid given to administer IV mediations and fluids used to “flush” the tubing in the calculation of the child’s total fluid intake.

Flushing buretrols / solusets

http://www.iv-therapy.net/node/1319Two great articles that explain the concept of

“flushing” the line after giving an IV medication

Syringe Pump

Calculation of fluids needs to includethe fluid in the syringe + the fluid in tubing.

•4 mL of medication + 5 mL in tubing •9 ml of fluid in total

Syringe pumps

http://www.youtube.com/watch?v=clh6kPXhOlE

Parenteral Pediatric Medications

Step 1: Convert lb to kgStep 2: Determine the safe range in mg/kgStep 3: Decide whether the dose is safe by

comparing the order with safe dose range Step 4. Calculate the dose neededStep 5. Check reference for diluent and

duration for administration.

Clinical Judgment 9-1

Bowden Textbook page 2172nd Edition

Example #1

Child: 5 years: weight 44 lbsOrder: famotidine (Pepcid) 5 mg IV bid

Drug Guide Information

Usual Dosage: 0.5 mg / kg / day divided twice daily

(maximum 40 mg / day)

Administration: May be administered IV push over a period not less than 2 minutes or as an intermittent infusion over 15 to 30 minutes; final concentration not to exceed 4 mg/mL.

Example #1

Convert pounds to kg: 44 lb = 20 kgDetermine safe dose:

20 kg x 0.5 mg = 100 mg 100 mg divided by 2 (drug is given twice a day) 5 mg is safe it meets mg / kg rule and does not exceed

40 mg/day. 5 mg bid = total of 10 mg/day

Example #1

Calculate the dosePepcid is provided as 10 mg/mL10 mg = 5 mg 1 mL x mL

5 = 10x 0.5 mL of Pepcid

Example #1

Calculate the dosePepcid is provided as 10 mg/mL10 mg = 5 mg 1 mL x mL

5 = 10x 0.5 mL of Pepcid

Example #2

Child: 4 years: weight 17 kgPhysician order: Fortaz (Ceftazidime) 280 mg

IV q 8 hours

Drug Guide Information

Dosing: Safe dose 30 to 50 mg/kg/day

Drug supplied as 1 gram powder. Directions: Dilute with 10 mL of sterile water to equal 95 mg/mL.

Administration: intravenous infusion over 15 to 30 minutes; may be given IV over 3-5 minutes at final concentration of 100 mg/mL

Example #2

Safe dose is 30 to 50 mg/kg/day• Low range: 17 kg x 30 mg = 510 mg/day• High range: 17 kg x 50 mg = 859 mg/daySafe range is 510 to 859 mg/day or 170 to 286

per dose.

If the order is to give the drug q 8 hours you would need to divide the safe range by 3 or multiple the q 8 hour dose x 3.

Example #2

Drawing up the medication:1 gram / 10 mL or 95 mg / 1 mL

95 mg = 280 mg 280 1 mL x mL 95x = 2.94 mL or 2.9

mL

DO NOT ROUND UP TO 3 mL

Example # 2

Adding medication to the volutrol Take the 2.9 mL of Ceftazidine – inject it into

the port on the volutrol and add additional IV fluid to = 10 mL.

Replacing NG Fluid Loss

NG – cc/cc replacement

If a child has a nasogastric tube that is draining fluid the physician will often write and order for: NG drainage – cc/cc replacement q 4 hours

What does this mean?

Nasogastric Output

NG output is measures q 4 hours.At the beginning of the shift the night nurse

reports that the drainage was 150 mL for the last 4 hours and you need to replace this over the next four hours.

Note: this is in addition to the IV hourly rate ordered.

Sample problem

IV hourly rate is 115 mL/hourNG output to be replaced over the next 4

hours is 150 cc’s or 37 mL/hour.IV would be set at 115 mL + 37 mL = You

would run the IV at 152 mL / hour for the next four hours.

Practice Problems

Do the practice problems.Can be done individually or in groups.Testing will be on like problems.You must achieve 90% or better to be able to

safely administer medications in the clinical setting.