drug therapy

The Basics

Special Populations

Considerations
  • Guided by key factors:
    • Age: Varies the response to medications.
    • Weight: Influences dosage and effects.
    • 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.