Pharmacological Concepts: Geriatric ConsiderationsMargarita Blajeva(Group 35, 2010)

ObjectivesDescribe the main physiological changes that occur with agingIdentify factors affecting absorption and distribution with the geriatric clientDescribe how drugs are metabolized and excreted in the elderlyExamine the issues related to drug compliance in the elderly population

DemographicsGeriatric populationlargest consumers of Rx medicationsthe higher the age, the higher the number of Rx drugs a person takesaverage usage ~ 3-4 drugs per senior (not uncommon to have 10+ Rx)nature and frequency of adverse drug reactions increase with age

Concerns with Geriatric Pharmacologychanges in body metabolismdrug interactionsdisease processeschanges in lifestyle

AgingEstimated that after 25-30 years of age, CO by 1% a year

Most body organs in size with age fewer cells to carry out organ functions

Changes the way in which body will cope with metabolic processes particularly important for pharmacology

Pharmacological changes:Drug absorptionDrug distributionDrug metabolismDrug excretion

Drug AbsorptionChanges to intestinal tract:decreased blood flowreduced absorptive surface areadecreased gastric secretionsdecreased motility

Result:SLOWED rate of drug absorptionSLOWED rate of drug action

Peak drug level:tends to decrease with agesame amount of drug will be absorbed but over a longer period of time

Drug DistributionChanges in body composition:Lean body mass (muscle) % decreasesBody water % decreasesBody fat increases(memory helper: people get weaker, fatter and dryer)

Because body fat increases with ageLipid soluble drugs = wider distribution

Lipid soluble drugs:Organs with greater fat (adipose tissue/muscle) will get more than younger adultsOrgans with lower fat content (liver/kidney) will get less than younger adults liver & kidney do most of the metabolism and excretion so

= SLOWED elimination= GREATER half life= GREATER duration of action

Drug DistributionBody water change = more drug in less fluidGREATER concentration of drugHIGHER concentration of drug in elderly patient

Water soluble drugs:Less bodily fluid to dissolve inLess distribution to organs with high adipose content

GREATER concentration of drug in certain organsGREATER pharmacological effects

Drug MetabolismIn generalRATE of drug metabolism decreases with agebut there is much variability

Why?Decreased blood flow to liver (less coming in/fewer resources available)Decreased production of liver enzymes

Mixed-function oxidase systemEnzymes responsible for oxidizing drugsTend to be strongly affected by the aging processDrugs that are oxidized (eg. Benzodiazepines) will be metabolized slower longer duration of drug action

Drug ExcretionMain routes of elimination:Renal & Gastrointestinal

Enterohepatic cyclingSome drugs also are eliminated by travelling through the liver, biliary tract, then intestinal tract

Some of these drugs, which undergo enterohepatic cycling, will not be eliminated at a final step but will re-enter circulation

increased half-life & duration

Drug ExcretionRenal excretionOne of the most greatly impacted systems by aging processRenal function decreases across the board: glomerular filtration rate (GFR) creatine clearance

What this means for medications that are primarily excreted by renal system: duration of action plasma drug concentrationpharmacological action

Therefore dosage must be reduced accordingly.

Drug ComplianceExtremely important issue in elderly

Challenges with elderly complianceComplicated dosing regimensConfusionage related memory losspathologic processes (Alzheimers, dementia, etc.)live alonelack of instructions for drug taking proceduresconfusion tends to be directly proportional to number of Rx medications takenPresence of unpleasant side effects of drug discourages use

Polypharmacy = multiple drug prescriptions

Drug ComplianceOther considerations:Understanding and training compliance may be increased dramatically with thorough instructions about the uses and methodology involved with a given medication

Form 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

Helping compliance:Understanding of the how and why: this should be done by physician but often is not

Developing easy to follow schedulee.g. Pill A after lunch/ Pill B before bed

Drug Compliance BLISTER PACK!!!

SummaryDemographics & Aging

Drug Absorption

Drug Distribution

Drug Metabolism

Drug Excretion

Compliance

THE END

**************A possible solution to patient compliance problems

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