Level of growth & development: Affects drug kinetics and safety.
Choice of drug:
Often restricted as most drugs have not been thoroughly researched in children.
Therapeutic dosage ranges:
Are less well defined in pediatric populations.
Pharmacokinetics in Children
A. Skin Characteristics and Drug Absorption
Thin skin and increased permeability:
Results in:
Increased absorption of topical drugs.
B. Blood-Brain Barrier and Drug Distribution
Immature blood-brain barrier:
Leads to increased distribution of drugs into the Central Nervous System (CNS).
C. Body Water Composition
Percentage of body water:
Children have a high body water composition, which can influence drug distribution.
Results in increased volume of distribution; drugs can be diluted more easily.
D. Protein Binding and Drug Activity
Protein binding until 1 year of age:
Greater amounts of unbound (ACTIVE) drug due to lower plasma proteins available for drug binding.
Notably, albumin levels are typically low during early infancy.
Renal Function:
The glomerular filtration rate (GFR) matures by 1 year of age.
This leads to slowed excretion of drugs, indicating that doses may need to be reduced.
E. Neonates & Infants Metabolism
Slowed metabolism during infancy:
The activity of liver drug-metabolizing enzymes reaches adult levels around 6 months.
Rapid metabolism occurs in children aged 1-4 years and decreases to adult levels at puberty.
Recommendation:
Continuous monitoring is necessary to avoid overmedication.
FDA Pregnancy Risk Categories
Category A:
Generally acceptable; controlled studies show no evidence of fetal risk.
Category B:
May be acceptable; animal studies suggest no risk but human studies not available, or minor risk shown in animals with no corresponding risks in humans.
Category C:
Use with caution; either animal studies show risk and human studies are not available, or neither types of studies were conducted.
Category D:
Positive evidence of human fetal risk; use only in life-threatening emergencies when no safer drug is available.
Category X:
Do not use in pregnancy; risks involved outweigh potential benefits and safer alternatives exist.
Drug Therapy in Older Adults
Key Concepts
Physiologic age:
Organ function is more significant than chronological age when considering drug therapy.
Separating effects:
It is often difficult to distinguish between the effects of aging, disease processes, and drug therapy.
Medication use:
Both prescription and over-the-counter (OTC) medications should be taken only when necessary.
Medication review:
Ongoing assessments of current medications, including OTC and herbal therapies, are imperative.
Practical Measures for Drug Therapy
Visual aids:
Use of large lettering on drug labels, magnifying glasses, and ensuring clients can open drug containers.
Scheduling tools:
Written schedules or specially designed drug containers for managing doses.
Support systems:
Enlist the help of family and friends to ensure adherence to medication regimens.
Monitoring:
Close monitoring for adverse drug effects is critical to ensure safety.
Learning Check
Question: A client taking levothyroxine for hypothyroidism becomes pregnant. What advice should the nurse provide?
Options:
A. The drug is safe to continue throughout pregnancy.
B. The client's risk of experiencing a toxic effect is increased.
C. The drug should be stopped immediately.
D. The drug is only safe during the third trimester.