Chapter 9: Drug Therapy in Pediatric Patients Flashcards
Pediatric Patients
All patients younger than 16 years old
Ongoing growth and development
Different age groups have different challenges
Two thirds of drugs used in pediatrics have never been tested in pediatric patients
Pediatric patients respond differently to drugs than the rest of the population
More sensitive to drugs than other patients are
Show greater individual variation
Sensitivity due mainly to organ system immaturity
Increased risk for adverse drug reactions
pediatric patient laws
Two laws:
Best Pharmaceuticals for Children Act (2002)
Pediatric Research Equity Act of 2003
These laws were permanently reauthorized as part of the FDA Safety and Innovation Act (FDASIA) of 2012
pediatric stages
Premature infants :Less than 36 weeks’ gestational age
Full-term infants: 36 to 40 weeks’ gestational age
Neonates: First 4 postnatal weeks
Infants: Weeks 5 to 52 postnatal
Children: 1 to 12 years old
Adolescents: 12 to 16 years old
pharmacokinetics: neonates and infants
Determining the concentration of a drug at its sites of action
Determining the intensity of the duration of response:
Elevated drug levels = more intense response
Delayed elimination = prolonged response
Immaturity of organs puts patient at risk for both of these responses
drug therapy in neonates and infants
Increased sensitivity in infants caused by immature state of:
Absorption
Protein binding of drugs
Blood-brain barrier
Hepatic metabolism
Renal drug excretion
pharmacokinetics: neonates and infants: absorption
Oral administration:
Gastric emptying time
Prolonged and irregular
Adult function at 6 to 8 months
Gastric acidity:
Very low 24 hours after birth
Does not reach adult values for 2 years
Low acidity: Absorption of acid-labile drugs is increased
IM:
Slow -muscles are not fully developed
Erratic
Delayed absorption as a result of low blood flow during the first few days of life
During early infancy, absorption of intramuscular drugs more rapid than in neonates and adults
transdermal:
More rapid and complete for infants than for older children and adults
Stratum corneum of infant’s skin is very thin
Blood flow to skin greater in infants than in older patients
Infants at increased risk of toxicity from topical drugs
pharmacokinetics: neonates and infants: distribution
Protein binding:
Binding of drugs to albumin and other plasma proteins is limited in the infant
Amount of serum albumin is relatively low
free drug [ ] higher = higher intensity
Endogenous compounds compete with drugs for available binding sites:
Limited drug/protein binding in infants
Reduced dosage needed
Adult protein binding capacity by 10 to 12 months of age
Blood-brain barrier:
Not fully developed at birth
Drugs and other chemicals have relatively easy access to the central nervous system (CNS)
Infants especially sensitive to drugs that affect CNS function
Dosage should also be reduced for drugs used for actions outside the CNS if those drugs are capable of producing CNS toxicity as a side effect
pharmacokinetics: neonates and infants: hepatic metabolism
The drug-metabolizing capacity of newborns is low
Neonates are especially sensitive to drugs that are eliminated primarily by hepatic metabolism
The liver’s capacity to metabolize many drugs increases rapidly about 1 month after birth
The ability to metabolize drugs at the adult level is reached a few months later
Complete liver maturation occurs by 1 year of age
pharmacokinetics: neonates and infants: renal excretion
Significantly reduced at birth
Low renal blood flow, glomerular filtration, and active tubular secretion
Drugs eliminated primarily by renal excretion must be given in reduced dosage and/or at longer dosing intervals
Adult levels of renal function achieved by 1 year
pharmacokinetics: childrens age 1 yr and older
Most pharmacokinetic parameters are similar to those of adults
Drug sensitivity more like that of adults than for children younger than 1 year old
important difference for pharmacokinetics: children age 1 year and older
One important difference:
Children in this age group metabolize drugs faster than adults
Markedly faster until the age of 2 years, then a gradual decline
Sharp decline at puberty
May need to increase dosage or decrease interval between doses
ADR in children
Children are vulnerable to unique adverse effects related to organ immaturity and ongoing growth and development
Age-related effects:
Growth suppression (caused by glucocorticoids)
Discoloration of developing teeth (tetracyclines)
Kernicterus (sulfonamides)
dosage determination
dosing is most commonly based on BSA -childrens BSA x adult dosage / 1/73 m2
initial pedatric dosng is, at best, an approx.
subsequent doses need to be adjsted
promoting adherence
Provide patient education in writing
Demonstration techniques should be included as appropriate
Effective education should include the following:
Dosage size and timing
Route and technique of administration
Duration of treatment
Drug storage
The nature and time course of desired responses
The nature and time course of adverse responses
