Question

Identify the pharmacodynamics and pharmacokinetic changes related to age in older adults. Identify the physiologic changes associated with increased age related to pharmacokinetics

Answer 1

1)Pharmacodynamics and pharmacokinetic changes related to age inolder adults:pharmacotherapy in the elderly is one of the challenging aspects of patient care so it is important to understand the pharmacological properties of drugs in elderly patients, different parts of pharmacokinetics such as distribution, metabolism and renal elimination are affected by age , renal elimination may be measured or estimated and other changes are difficult to measure and pharmacodynamic changes with aging affect both beneficial and adverse effects in most organs.pharmacokinetics it is the defined as what the body does to the drug and it includes absorption , distribution across body compartments and metabolism and excretion , with aging there are changes in these areas some changes are more clinically relevant the metabolism and excretion of many drugs decrease requiring that doses of some drugs decrease requiring that doses of some drugs be decreased and toxicity may develop slowly because concentrations of chronically used drugs increased for 5 to 6 half lives until a steady state is achieved, absorption : there is deccrease in small bowel surface area slowed gastric emptying and an increase in gastric pH changes indrug absorption tend to be clinically inconsequential for most drugs, distribution: with age body fat generally increases and totoal body water deccrease and increased fat increases the volume of distridution for highly lipophilic drug and may increase their elimination half lives, hepatic metabolism : overall heaptic metabolism of many drugs through the cytochrome p 450 enzyme system decrease with age, renal elimination: the renal elimination of drug decreased with age. b) pharmacodynamics in older adults:it is defined as what the drug does to the body or the reponse of the body to the drug it is affected by receptor binding postreceptors and chemical interaction. in older adults the effects of similar drug concentrations at the site of action may be greater or smaller than those in younger people , differences may be due to changes in drug receptors interaction in postreceptor events or in adaptive homestatic responses and among frail patients are often due to pathologic changes inorgans. 2) physiological changes associated with increased age related to pharmacokinetics:the total body fat increases and decreased lean body mass and tatla body water and GI motility and plasma protein and hypochlorhydria and the pharmacokinetics parameters are absorption in it the unaffected for IV drugs and extent of absorption may be complete and reduced for drugs requiring lower pH environment and it shows that there is slight decreae in absorption, distrubtion : there will be reduced for water soluble drugs bound to muscle and increased for lipid soluble drugs and may requires dosage reduction of hydrophilic drugs and may observe prolonged time to elimination of lipophoilc drugs etc. b) there is decreaed hepatic mass and hepatic blood flow it results in reduced first pass metabolism and reduced phase 1 metabolism and potential increase in bioavilability of durgs subject to extensive hepatic metabolism and increased drug exposure c) decrease caridac output and blood flow to kidneys and liver and renal mass and renal or hepatic clearance results in reduced renal elimination and increased elimination half life and results in increased plasma concentration of drug .