Class 3 - Pharmacokinetics and Pharmacodynamics

older adults and medications

older adults are the largest users of prescription medications and OTC

what kind of medications are talked about?

prescription, OTC, natural remedies, herbal

why are adverse drug reactions more common in older adult

because the known therapeutic responses of medications are less understood in them due to trials to determine the appropriate therapeutic dosages are conducted on younger adults

what's associated with ADR

increased mortality and morbidity for older adults

what are gerontological nurses responsibility with older adults and medication

-be knowledgeable

-educate patients

-minimize risks associated with taking medications

define pharmacokinetics

how a drug moves through the body

define pharmacodynamics

what the drug does to the body

define polypharmacy

Taking multiple medications at the same time (5 meds) (these can be herbals, supplements, and OTC medications)

-use of more medications than is clinically indicated

define adverse drug reactions (ADR)

unwanted undesirable effects that are possibly related to a drug

define anticholinergic syndrome

-Occurs when a person takes too many medications that blocks acetylcholine

-there are benefits to blocking acetylcholine such as to promote urinary continence, to reduce motion sickness, and to reduce allergy symptoms

-ADR can occur when the amount of acetylcholine blocked inhibits normal body function

-Many medications block acetylcholine -- i.e., antihistamines, antiemetics

-Central inhibition leads to an agitated (hyperactive) delirium - typically including confusion, restlessness and picking at imaginary objects

what are the 4 pharmacokinetic properties?

-absorption

-distribution

-metabolism

-excretion

what are the age-related changes that impact pharmacokinetics of medication?

-can impact the risk of drug toxicity (this is bc the meds stay in the body for a longer period of time, thus it can build up and can be toxic to the older adult)

-delayed stomach emptying (may diminish or negate the effectiveness of short-lived medications)

-increased motility in the small intestine (med effect is diminished bc of short contact time)

-decreased hepatic blood flow, enzyme induct ability, enzyme activity

-decrease absorptive surface area

-increased toxic effects because decrease albumin levels

-change in body composition, particularly decreased lean body mass and increased body fat

-decreased glomerular filtration, leading to increased half-life

-increased risk for ADR

how long between administration and absorption in older adult?

DEPENDS ON ROUTE OF INTRODUCTION

-sometimes when pt is acutely ill, need to do IV to get to the target organ (like heart) which expedites effects of medication

what are the changes in the older adults body that might impact the time it takes for the drug to be absorbed?

-increased body fat, decrease lean body mass

-diminished gastric acidity

-slower stomach emptying (diminish activity of short lived medications)

-slowed gastric emptying can increase the effect of the medication

-epidermis is thinner and is drier so decreased absorption rate

-changes in gastric motility (impacts the amount of time for medication to be absorbed in the body)

how do the changes in the older adults body change the absorption of the medication?

-slower gastric emptying can cause a time delay in maximum drug conc

-transdermal may lead to decreased concentration of drug in the blood

-inconsistent changes

what medications or food can influence the absorption of medications?

i.e., grapefruit juice delays with a medication for hypothyroidism (levothyroxine) -- may delay the absorption of the medication

-i.e., increased leafy greens in diet can counteract the anticoagulant effects of Coumadin (taken for heart conditions to decrease atrial fibrillation) and aspirin

how does the body influence the distribution of the drug or its transportation to its target organ?

-amount of plasma protein available for the drug to bind to, will effect medication distribution

-amount of available fat can affect distribution because some meds attach to fat cells (lipophilicity)

-amount of water available in the body can affect distribution because some meds are attracted to water (hydrophilicity)

what are the changes in the older adults body that might change the distribution of the drug?

age-related changes includes: prolonged illness, malnutrition, dehydration all can increase medications toxicity

what is the effect of the age related changes in the distribution of the drug in the body

-Change: older adults with prolonged illness or malnutrition can have a decrease in plasma protein

effect: this decrease in plasma protein increases the activity of the medication and can lead to toxic levels of medication

-Changes: older adults experiences changes in body composition: increased body fat and decreased body water

effect: drugs that bind to water will increase effect (i.e., digoxin) and drugs who bind to fa will have a prolonged effect (i.e., diazepam)

-Change: reduced blood flow in the liver

effect: can lead to increase in the amount of time the medication stays in the body (increasing half life)

how does the body influence the metabolism of the drug?

-metabolism changes the chemistry of the drug so it can be excreted or removed from the body

-metabolism predominantly occurs in the liver

what is metabolism?

it is the process in which the body modifies the chemical structure of the medication in able for it to be excreted from the body

what is half life?

it is the measure of the amount of time the drug is active in the system

how does the body influence the excretion of the drug?

primarily excreted through the kidneys, also via bile, saliva and sweat

how do changes in the older adult influence excretion?

decreased blood flow through kidneys and decreased kidney function (the glomerular filtration rate)

how do changes in the older adults body change the excretion of the drug?

often means that the drug is in the body longer and increases risk for toxicity

how do we check the body rate for excretion

creatinine clearance is used as an indication of the efficiency of the glomerular filtration rate -- thus a decreased creatinine clearance should lead to a decreased dosage of some medications

which phase of the pharmacokinetic process that starts with administration of the medication

absorption

what is an age-related change associated with the elimination of the medication that can increase risk for drug toxicity?

decreased glomerular filtration rate and decreased blood flow through kidneys

what is the most significant age-related change that can affect the metabolism of medication?

decreased blood flow through the liver

what is the most significant age-related change in pharmacokinetics?

metabolism and excretion

why is metabolism on of the most significant age-related changed regarding pharmacokinetics?

decreased blood flow through the liver will increase the half-life of the drug thus the drug stays in the body for a longer period of time

how does lipophilicity and hydrophilicity affect the therapeutic effects of meds

older adults increase in fat composition and increases fluid retention thus those drugs are exaggerated

how does polypharmacy contribute to ADR?

-increases risk for medication interaction

-increases risks for age-related changes to alter therapeutic effectiveness of the medication

-increases the risk for misuse of meds (medication errors, taking meds at wrong time, etc)

Medication interactions

greater risk for interactions with another medication, food, or herbal products

-can potentiate the impact of another medication -- can make one medication more effective or make both less effective

-can change the pharmacokinetic activity by altering the body ability to absorb, distribute, metabolize or excrete medication (can increase or decrease the half life of meds)

Changes in pharmacodynamics with age

-changes in sensitivity of the receptors for medications that are on the cella can change and result in decreased or increased response to the medication

what are the drug classes that lead to ADR's in older adults?

anticoagulants, antibiotics, antineoplastic medications and opiods

relationship of ADR and older adult

-older adults that are on 10-14 different drug classes are 5 times more likely to be hospitalized than those prescribed 4 or fewer

-older adults in LTC settings are at a higher risk for ADRs

-increased risk for drug induced delirium

what are the type of drugs that may increase the risk of drug induced delirium?

antidepressants, antihistamines, antiparkinsonian agents, antipsychotics, benzodiazepines

what is the most common medication cause of delirium in older adults?

anticholinergic

what is Beers criteria

-medications are considered appropriate to not, according to the patient's condition

-identifies potentially inappropriate medications that may exacerbate the disease or syndrome and those that should be used with caution

what happens if acetylcholine is blocked?

-cognitive impairment, an acceleration of neurogenerative process, the appearance of psychotic or confusional symptoms and functional disturbances

-dry mouth, urinary retention, constipation, paralytic ileum (motor activity of the bowel is impaired), increased HR and blurred vision

misuse of medication includes what

overuse, underuse, erratic use and contraindicated use

what's the main reason polypharmacy increases the risk of medication misuse?

when older adults do not understand why they're taking a medication or when they need to take the medication

what are factors that contribute to polypharmacy and misuse of medication

-Health provider/systems factors

-Older adult

what is the health care provider/system factors in polypharmacy?

-usually health care providers do not look at the reason for why a symptom is occurring and only prescribe more medication to overcome the presented symptom — we need to look at how the medications that they're currently on contribute to the symptoms they are experiencing

-Health care providers also lack information about medications from older adults various sources of medication (sometimes elderly don't even know the meds they're taking) and also lack of information about patient med adherence

-also lack of info about the older adults (changes in weight, daily habit changes, mental-emotional patterns)

what are the psychosocial factors of older adults regarding polypharmacy?

-lack of knowledge, purpose of meds and info about how and when to take them, sensory issues (ability to read prints and directions, ability to hear directions), physical issues (ability to swallow, ability to open the bottle and remove it from bottle, dexterity applying meds like nasally or transdermally)

-older adults wanting a quick fix, lack of ADR knowledge of OTC

-communication barriers -- sometimes they don't want to talk about the issues they're having as they're in denial. Assumption that once they're on the medication, that they should stay on that med and that it should not be changed. Assumption by patient that you cannot develop ADR after being on the meds for a long time (need to be aware of this especially with their age-related changes)

-financial considerations

what are factors impacting the older adults misused of medications?

-cognitive impairment

-social isolation and depression

-asymptomatic diseases

-low health literacy

-adverse medication effects

-long treatment duration

-high number of medications

-poor communication and misunderstanding about the medications or disease

describe the societal factors that can contribute to polypharmacy

-wanting a quick fix

-low health literacy typically

-not aware that they can develop ADR on meds they've been taking a long time

describe those factors that are related to the health provider

lack of time with the older adult to listen and really go through what medications the older adult is already on and how the older adults has probably channges (their physical change, altered response, change in diet, malnutrition, new illness, etc)

List the components of a comprehensive medication assessment

-review of all medication (brown bag assessment where brown bag assessment is looking at all the medications the patient is on, whether prescribed or OTC — this is when we ask them to actually bring in all of their medication to their appointment (we also ask what they are taking the medication for), this usually tells us what the issues with the older adults are) --> look for potential med interaction & recognize conditions making it hard for them to self medicate

-medical assessment including: frailty, malnutrition, dehydration, kidney functions. Discuss method for self administration

-matching medical diagnosis with prescribed medications (physician would do this, not nurse) -- this is called a medication reconciliation. Monitor for ADR (watch for falls, delirium, and change in function)

-review of systems and monitoring to determine the need for meds

to reduce polypharmacy, HCW should:

-instruct patients to bring all meds (brown bag)

-screen for unnecessary drugs at each medical visit

-prescribe drugs with better or less side effects or simplify their drug regimen

-ensure the pt thoroughly understands their drug regimen by providing clear WRITTEN instructions

medication-taking behaviours involves:

motivation

knowldege

culture

cost and accessibility

ability to distinguish correct container

ability to read and comprehend directions

ability to hear and remember verbal instructions

knowledge about correct timing

ability to follow the correct dosage regimen

physical ability to open and dispense the appropriate dose of med

ability to swallow

additional skills related to manual dexterity

what is the STOPP/START criteria?

-STOPP screening tool of older adults prescription

-START screening tool to alter doctors to right treatment

-identifies inappropriate medication and predicts adverse events

-lists medication that could be used as long as there are no contraindications

-widely used in European countries

-prevents ADE

what are ways to monitor and evaluate the effectiveness of medication?

VS

ADLs

Sleeping

eating (appetite)

hydrating

eliminating

falls

pain assessment

changes in mental status (alertness, attention, memory, orientation, behaviour, mood, affect, and content)

blood levels

QUESTION THE NEED TO BE ON A MEDICATION IF THERE ARE NO LONGER SYMPTOMS

describe the appropriate use of antipsychotic medications

-antipsychotics are used to treat psychotic symptoms: hallucinations, thought disorders

-antipsychotics are used for people with disorders such as schizophrenia, mania, depression

-often used inappropriately in the older adult population (esp in LTC) to control disruptive behaviours (called responsive behaviours)

-prescribing antipsychotics for a person with dementia as a first line of defence is NOT recommended bc of ADR

-antipsychotics increases the risk of an older adult for delirium, falls and functional decline

what are the risks of antipsychotic meds?

-unlikely to see first line antipsychotics

-more likely to see second generation antipsychotics bc they're supposed to have fewer side effects

-causes orthostatic hypotension

-anticholinergic effects

-reduced ability to manage temperature extremees

risk of neuroleptic malignant syndrome

what is neuroleptic malignant syndrome?

a life-threatening neurologic emergency associated with the use of antipsychotic (neuroleptic) agents and characterized by a distinctive clinical syndrome of mental status change, rigidity, fever, and dysautonomia

-can cause death due to long-term use of antipsychotics -- can cause hypertension, reduce sweating and stability to manage sweats - thermal regulation also declines

how common is medication misuse?

80%

factors associated with medication misuse

Cognitive impairment, social isolation, depression, asymptomatic disease, low health literacy, adverse medication, long treatment duration, high number of medications, poor communication and misunderstanding about the medications or disease