Drug Response In Infants & Children & Geriatrics PDF

Drug response in infants & children  Drug response in infats & children Drug response in infants & children may differ from adults due to the following: 1. Body built: Total body water is more than in adults and is mostly extracellular. Fat conten is lower in children...

Drug response in infants & children  Drug response in infats & children Drug response in infants & children may differ from adults due to the following: 1. Body built: Total body water is more than in adults and is mostly extracellular. Fat conten is lower in children Percutaneous absorption increases due to thin skin.  2. GI function: Gastric acid output is less in neonates than adults. 3. Plasma protein binding It is reduced in neonates due to lower albumin concentration. 4. Blood brain barrier (BBB ) is more permeable in neonates. 5. Hepatic enzyme activity It is low in neonates 6. Renal clearance It is less efficient Adult glomerular filtration rate is attained after 3-5months; Adult secretory and reabsorptive capacity is attained after 7 months. Drugs that depend on renal elimination e.g. Aminoglycosides (antibacterial), are cleared from the body very slowly in the first weeks of  Drug response in geriatrics Effects of aging Aging affect both pharmacokinetics and dynamics of drugs A. Pharmacokinetics 1. Drug Absorption Reduction in blood flow, absorptive surface area in intestine, gastric secretions and delayed gastric emptying As a result there is SLOWED rate of drug absorption and SLOWED rate of drug action 2. Drug Distribution Reduction in muscle and water content and increase fat content Lipid soluble drugs have: – SLOW elimination – GREAT half life – GREAT duration of action 3. Drug Metabolism RATE of drug metabolism decreases with age due to decreased production of liver enzymes 4. Drug Excretion by kidney Decreased elimination increased half-life & duration B. Pharmacodynamics Drug responses in the elderly differ from adults due to: – Alteration of receptor – Age-related impairment of physiological adaptive mechanisms  Challenges with elderly compliance Complicated dosing regimens and polypharmacy Confusion – Age related memory loss – Pathologic processes (Alzheimer's) – Live alone This confusion tends to be directly proportional to number of Rx medications taken  Presence of unpleasant side effects of drug discourages use Form of the drug – patients may have difficulty with certain forms of medications (e.g. swallowing large capsules) Container – may be difficult to open, or difficult to read and understand Good luck