Drug Response in Infants and Geriatrics

Drug Response in Infants and Children

• Total body water is higher in infants and children compared to adults, mostly situated outside cells.
• Fat content is lower in children.
• Percutaneous absorption is higher in children due to thinner skin.
• Gastric acid production is lower in newborns than adults.
• Plasma protein binding is reduced in newborns due to lower albumin concentration.
• The blood-brain barrier (BBB) is more permeable in newborns.
• Hepatic enzyme activity is low in newborns.
• Renal clearance is less efficient in infants and children compared to adults.
• The adult glomerular filtration rate takes 3-5 months to develop.
• Full adult secretory and reabsorptive capacity takes 7 months to develop.
• Drugs relying on renal elimination, such as Aminoglycosides (antibacterial), are cleared slowly in the first weeks of life.

Drug Response in Geriatrics

• Aging impacts both pharmacokinetics (drug movement in the body) and pharmacodynamics (drug effects on the body).

Pharmacokinetics

• Reduced blood flow, absorptive surface area in the intestine, gastric secretions, and delayed gastric emptying can lead to slower drug absorption and slower onset of action.
• Reduced muscle and water content, with increased fat content, can cause lipid-soluble drugs to have slower elimination, longer half-life, and longer duration of action.
• Drug metabolism rate decreases with age due to decreased production of liver enzymes.
• Decreased renal drug excretion leads to increased half-life and duration of action.

Pharmacodynamics

• Drug responses in the elderly differ from adults due to alterations in receptors and age-related impairment of physiological adaptive mechanisms.

Challenges with Elderly Compliance

• Complicated dosing regimens and polypharmacy (taking multiple medications) can contribute to confusion.
• Age-related memory loss, pathological conditions like Alzheimer's, and living alone can further contribute to confusion.
• This confusion often correlates with the number of medications taken.
• Unpleasant drug side effects can discourage medication use.
• Some drug forms, like large capsules, can be difficult for elderly patients to swallow.
• Medication containers might be challenging to open, read, or understand.

Explore the differences in drug response between infants, children, and geriatrics. This quiz will cover key physiological factors influencing pharmacokinetics and pharmacodynamics, providing insights into safe medication use across age groups.