Dosing of drug in Pediatric Patients.ppt 1.ppt

Dosing of drugs in Pediatric Patients - Pharmacotherapeutics -1

1. Dosing of drug in Pediatric
Patients
By:- Ravinandan A P
Dosing of drug
in
Pediatric Patients
By:- Ravinandan A P

2. Introduction
•Children are not small adults. So while
adjusting the dose for pediatric one has to remember that
child is not mini adult.
•It is a branch of medicine dealing with children’s disease.
•The pediatric population comprises 20 -25 % of the total
population. (2003 prediction 18%)
•Numerous acute & chronic disease can affect this population.

3. •Children form a large % of the patient
population, but they have been a neglected
group where medicines are concerned.
•It is not that children do not have access to
medicines, but that few products have been
designed and tested specifically for paediatric
use.

4. •Children are not simply small adults &, although
numerous, are not a homogeneous population.
•The change in the metabolism &
pharmacokinetics of drugs in children is rapid in
the first few weeks & months of life.
•Even as the child grows the methodology of
calculating doses is not precise.

5. •The sulfanilamide & Thalidomide
tragedies (death due to sulfanilamide
elixir, & birth defects among the
newborns from mothers who had used
thalidomide for morning sickness) led to
more strict governmental requirements
for drug approval for pediatric patients.

6. •Pediatrics is the branch of medicine dealing
with the development, disease and disorders
of children.
•Infancy & childhood is a period of rapid
growth & development.
•Organs drug handling capacity differs from
neonates/infants/children to adults.
•Hence ADR, dosage and formulations differs.

7. Pediatric age group
1.Neonates -- Birth to 1 month (4weeks)
2.Infants -- 1 month to 1 year
3.Children--1 year to 12 years
4.Adolescent--12 to 18 years

8. •For the purpose of drug dosing one can
consider children above 12yrs as adults.
•But, sometime this is inappropriate because
some children not been through puberty and
not reached adults height and weight.

9. International Committee on
Harmonization 2001 (ICH)
•Divided into following age ranges:
•1. Preterm newborn infant
•2. Term newborn infant (0-27 days)
•3. Infants and Toddlers (28 days to 23 months)
•4.Children (2-11 yrs)
•5. Adolescents (12-16/18years)
Preterm refers to a baby born before 37 weeks of pregnancy has been
completed. Usually, a pregnancy lasts about 40 weeks.

10. •Infancy & childhood is a period of rapid
growth & development.
•One should consider the
 absorption,
distribution,
 metabolism,
 excretion (ADME) before adjusting the dose.

12. Absorption
•The absorption rate is slower in neonates than
in older infants & children.
•Absorption in infants & children after IV
injection is noticeably faster than in neonates
due to increased muscle blood flow.

13. Distribution
•Pediatrics has 1% of total body water & ECF
volume decreases with age.
•Thus, water-soluble drugs such as
aminoglycosides require larger doses on a mg/kg
body weight basis in neonates than in older
children to reach similar plasma concentrations.

14. Pediatric Priors Pediatric Priors
DistributionDistribution
0 20 40 60 80100
Premature
Newborn
4 mos
12 mos
24 mos
36 mos
Adult
Percentage of Total Body WeightPercentage of Total Body Weight
Extracellular WaterExtracellular WaterIntracellular WaterIntracellular WaterProteinProteinFatFat
OtherOther

16. •For EX: The neonatal dose of Gentamycin is
3mg/kg/dose. While the child dose is
2.5mg/kg/dose.
•Another factors has to be consider while deciding
dose for pediatric population is concentration of
protein in the serum. Usually the concentration
of 2 protein (albumin & globulin) is less in
younger age group compare to older.

17. Drug Metabolism
•Between 1-9 years of the age group, in particular the
metabolic rate or clearance rate is higher than the adult.
•Because these age group require higher dosage compare to
adult.
•Hence medications like Theophylline, Phenytoin, &
Carbamazipine require high dosage in children of 1-9 years
compare to adult.

18.  Example :
• The dose of Theophylline for 1-9 yr children
is= 24mg/kg/day.
•While children for 9-12 yr it is = 20mg/kg/day.
•While 12-16 yr it is 18mg/kg/day.
•For adult 13 mg/kg/day.

19. Renal Excretion
•Usually children have lesser GFR compare to
adult due immature of the kidney.
•EX:- Digoxin t1/2 = 20-70 hrs in baby less than 2
months.
•While if the child is 16 months = 12-42 hrs.

20. Formulas to calculate dose for
Pediatric.
1 Young’s formula
= Age in year Adult dose
Age in year + 12
= Dose of Pediatric

21. 2 Fried’s formula / rule
= Age in month Adult dose
150
= Dose of Infant / Pediatric
3 Clark’s formula
= Weight in pounds Adult dose
150
= Dose of Infant / Pediatric

22. Based on Body Surface Area (BSA)
= Surface area of child Adult dose
1.7
•The 4
th
way of determining the dose of
pediatric is based on the nomogram.
•The basic determining the dosage will be the
Body Surface Area (BSA) of infant & children
based on nomogram.

23. •The Mosteller formula
•BSA (m
2
) = SQRT( [Height(cm) x Weight(kg) ]/
3600 )        
•e.g.
BSA = SQRT( (cm*kg)/3600 )
•or
in inches and pounds:     
•BSA (m
2
) = SQRT( [Height(in) x Weight(lbs)]/
3131 )

24. •Average BSA for children of various ages, for men, and for
women, are taken to be:
Neonate (newborn) -
 0.25m²
Child of 2 years - 0.5m²
9 years
      - 1.07m²
10 years - 1.14m²
12–13years - 1.33m²
Women - 1.6m²
Men - 1.9m²
There was an average BSA of
 
1.73 m
2

25. To determine BSA with nomogram.
1.Child height & weight are plotted on left & right
vertical column.
2.A straight edge is placed on the vertical height
& weight line.
3.BSA is the point where line crosses the surface
area.

26.  Based on the surface area one can calculate
the child dose.
Formula
= Surface area Adult dose
1.7
= Child dose.