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Chapter 9

Safe Medication Use

Older adults who are 65 years and older are the largest user group of prescription and over-the-counter medications
Prescription medications can afford survival or enhance quality of life for those with chronic conditions and disabilities

Older Adults and Medications

Pharmacokinetics is the movement of a drug throughout the body from the point of its administration as it is
Absorbed
Distributed
Metabolized
Excreted

Pharmacokinetics

Amount of time between drug administration and absorption depends on
Bioavailability
Amount of drug that passes into the body
Route of administration
Routes of administration include intravenous, oral, parenteral, transdermal, and rectal methods

Absorption

Physiological changes and effect of other drugs can alter absorption
Increased gastric pH retards acid-dependent drugs
Delayed stomach emptying diminishes the effectiveness of short-lived drugs
Increased motility in the small intestine diminishes drug effect because of shortened contact time
Slowed intestinal motility increases the contact time, amount absorbed, and effect

Absorption (Cont.)

Medication must be transported to the receptor site on the target organ to have an effect
Distribution depends on the availability of plasma protein in the form of lipoproteins, globulins, and albumin
Age-related changes in distribution are related to changes in body composition, increased body fat, and decreased total body water

Distribution

Process by which the body modifies the chemical structure of the drug
Primarily occurs in the liver
Normal age-related physiological changes can affect metabolism
Liver’s activity, mass, volume, and blood flow are normally reduced
Hepatic clearance of medication is decreased by 30% to 40%

Metabolism

Medications are excreted in sweat, saliva, and other secretions, as well as mainly by the kidneys
Normal age-related physiological changes can affect metabolism
Kidney function decreases with aging (up to 50% by 80 years of age)
Prolongs the half-life of a drug or the amount of time required to eliminate the drug
Cockcroft-Gault equation estimates creatinine clearance

Excretion

Interaction between a drug and the body
The older a person gets, the more likely there will be an altered or unreliable response of the body to the drug
Several known mechanisms
Decreased response to beta-adrenergic receptor stimulators and blockers
Decreased baroreceptor sensitivity
Increased sensitivity to anticholinergics, benzodiazepines, opioid analgesics, warfarin, and the cardiac drugs diltiazem and verapamil

Pharmacodynamics

Relationship between biological rhythms to the variations in the body’s response to drugs
A developing science that may lead to a more effective drug therapy
Biorhythmic variations occur in
Gastric acid pH
Gastrointestinal tract motility and blood flow
Albumin levels
Glomerular filtration and urine acidity

Chronopharmacology

Before administering a drug to an older adult, the nurse should understand that the dose may be impacted which age-related physiological change?

Older adults have increased liver metabolism

Gastric emptying often occurs more rapidly

Older adults have reduced glomerular filtration rates

The sensitivity to baroreceptors is often reduced

Question

C—The decreased glomerular filtration rate prolongs the half-life of drugs, adding to the risk for accumulation and increasing the potential for toxicity or other adverse events.

Answer

Polypharmacy
Drug interactions
Medication–herb/supplement interactions
Medication–food interactions
Drug–drug interactions
Adverse drug reactions
Misuse of drugs

Medication-Related Problems and Older Adults

Use of approximately five or more medications or the use of multiple medications for the same problem
Major concerns are the increased risk for drug interactions and the increased risk for adverse events
May be unavoidable but can result from fragmented communication

Polypharmacy

When two or more medications or foods are taken together or close together, they may cause a change in the effectiveness of the other
Effects may be increased, decreased, or variable
Polypharmacy increases the risk for and the frequency of medication–medication interactions

Drug Interactions

Medication–Medication Reactions

An unwanted pharmacologic effect
Range from minor annoyances to unwanted pharmacological effects and death
Common in those older than 65 years of age
Commonly observed adverse reactions in older adults include drug-induced delirium, confusion, and lethargy

Adverse Reactions

Includes
Overuse
Underuse
Erratic use
Contraindicated use
May be accidental or deliberate
Misunderstanding or inability to read labels or understand instructions
Make medication last longer for financial reasons
Believe the dose is either too low or high
Forget to take the medication correctly

Misuse of Drugs

Their potential for harm is greater than their potential benefits
Beers list (1997)
Identifies drugs that carry a higher-than-usual risk when prescribed for older adults
Incorporated into regulatory policy for long-term care (LTC) facilities and are part of quality measures
Using a “do not use” medication in LTC without documentation of overwhelming benefit is considered medication misuse by the prescriber

Inappropriate Medications

Alter brain chemistry, emotions, and behaviors
Have a high risk of adverse events
Medications included in this category are
Antidepressants
Antianxiety agents
Mood stabilizers
Antipsychotics
Sedative-hypnotics

Psychoactive Medications

SSRIs (e.g., Zoloft, Prozac, Lexapro, and Celexa) and SNRIs (e.g., Effexor)
Drugs of choice for use in older adults
Effective, with minimal side effects
May cause nausea, dry mouth, sexual dysfunction
Use with caution in persons with a history of falls because of the potential to produce ataxia or dizziness
Tetracyclic mirtazapine (Remeron) useful in treating sleep problems in older adults

Antidepressants

Include benzodiazepines, buspirone (BuSpar), and beta blockers
Benzodiazepines
Most frequently used but should be avoided
Older adults slowly metabolize these drugs and have decreased excretion
Side effects include drowsiness, dizziness, ataxia, cognitive deficits, and memory impairment

Antianxiety Agents

Used to treat bipolar disorder
Include
Lamotrigine (Lamictal)
Lithium
Anticonvulsants—carbamazepine (Tegretol), valproic acid (Depakote), and gabapentin (Neurontin)
Atypical (Abilify, Zyprexa, and Seroquel)
Each has a very individualized drug–drug interaction profile

Mood Stabilizers

Used for treating psychotic symptoms and for mood stabilizing effects
Pose significant risk of cardiac events
Inappropriate use may mask a reversible cause of a problem
Drugs with the lowest side effects profile and at the lowest dose possible and for the shortest length of time should be prescribed

Antipsychotics

Risk of serious side effects increases in older adults
Neuroleptic malignant syndrome
Extrapyramidal syndrome (EPS) reactions

Acute dystonia

Akathisia

Parkinsonian symptoms

Tardive dyskinesia

Antipsychotics (Cont.)

Nurses are responsible for assessing, monitoring, evaluating, and educating persons regarding safe medication use
The nurse and patient must decide together when a PRN, or “as needed,” medication is indicated

Implications for Gerontological Nursing and Healthy Aging

Comprehensive medication assessment
“Brown bag approach”
24-Hour medication recall
Systems approach
Medication reconciliation with interfacility transfers
Look for discrepancies between the prescribed dosage and the actual dosage, potential drug–drug and food–drug interactions, and potential or actual adverse drug reactions

Assessment

Key persons
Environment
Timing
Communication
Reinforce teaching

Patient Education

Difficulties opening bottles as a result of arthritis
Use of pill cutters
Difficulty swallowing medications
Use of accurate medication-measuring devices
Proper administration of enteric-coated, extended-release, or sustained-release medications
Use of transdermal patch

Medication Administration

Monitor and evaluate the effectiveness of medications and observe for signs of problems
Assess and document changes in physical and functional status
Measure blood levels when needed
Promptly communicate potential problems to the prescriber
Determine severity of side effects
Promote actions necessary to prevent drugs from becoming toxic

Monitoring

To reduce polypharmacy in an older adult, the nurse should

give all medications to a family member instead of the patient.

encourage the patient to refill all of his or her medications at one time.

transmit prescriptions to the patient’s pharmacy electronically.

obtain a complete medication assessment with each patient encounter.

Question

D—Conducting a comprehensive drug assessment is the most effective way to reduce polypharmacy. Electronic transmitted prescriptions and filling all prescriptions at once may still involve multiple pharmacies.

Answer