http://evolve.elsevier.com/McCuistion/pharmacology
By 2033, persons over the age of 65 will outnumber those under the age of 18 in the United States. There are expected to be over 98 million older adults by the year 2060, with close to 20 million over the age of 85. These numbers are staggering, more so considering 92% of older adults have at least one chronic illness, and over 75% of older adults have two chronic illnesses. Typically, persons with two or more chronic conditions take five or more prescription drugs.
Over half of all older adults use at least one over-the-counter (OTC) drug, and nearly three-quarters of older adults use at least one supplement to augment their prescription drugs; however, older adults are more likely to experience adverse reactions or drug interactions related to OTC drugs and supplements, many times resulting in hospitalization.
Administration of drugs in the older adult population requires special attention to age-related factors that influence drug absorption, distribution, metabolism, and excretion. Drug dosages are often adjusted according to the older adult’s weight, laboratory results (e.g., liver enzymes and glomerular filtration), and comorbid health problems. Because of altered organ function in the older adult, the effects of drug therapy must be closely monitored to prevent adverse reactions and possible toxicity.
Drug toxicity may develop in the older adult for drug doses that are within the therapeutic range for the younger adult. These therapeutic drug ranges are usually safe for young and middle-aged adults but are not always within the safe range for older adults. It has been suggested that drugs for older adults should initially be prescribed at low dosages with a gradual increase in dosage based on therapeutic response; this practice is commonly stated as start low and go slow. This approach to drug prescribing reduces the chance of drug toxicity.
Common characteristics in older adults that increase the risk for problems with drug administration include lack of coordinated care, recent discharge from the hospital, self-treatment, multiple diagnoses, sensory and physical changes associated with aging, multiple health care providers, and cognitive impairment.
Physiologic Changes
Physiologic changes associated with aging can influence absorption, distribution, metabolism, and excretion of drugs as well as pharmacodynamic responses at receptors and target organs. These physiologic changes include the following:
• A reduction in total body water and lean body mass, resulting in increased body fat, which alters the volume of distribution of drugs.
• A reduction in kidney mass and lower kidney blood flow, leading to a reduced glomerular filtration rate (GFR) and reduced clearance of drugs excreted by the kidneys.
• A reduction in liver size and blood flow, resulting in reduced hepatic clearance of drugs.
A decline in the physiologic processes that maintain equilibrium in the older adult may mean a higher incidence of adverse effects. Examples of this include:
• Postural hypotension in response to drugs that reduce blood pressure
• Volume depletion and electrolyte imbalance in response to diuretics
• Excessive bleeding with anticoagulant and antiplatelet drugs
• Altered glycemic response to antidiabetic drugs
• Gastrointestinal (GI) irritation with nonsteroidal antiinflammatory drugs (NSAIDs)
Physiologic changes with aging affect the determination of risk versus benefit underlying drug choice, dose, and frequency.
Pharmacokinetics
Pharmacologic processes have not received adequate study in the older adult, therefore a thorough understanding of pharmacokinetics is necessary for the safe administration of drugs in this population.
Absorption
Adults experience several GI changes with aging that may influence drug absorption. These include a decrease in small-bowel surface area, slowed gastric emptying, reduced gastric blood flow, and a 5% to 10% decrease in gastric acid production. These changes are not always clinically relevant; however, calcium carbonate is affected by the decreased gastric acidity. Older adults should be prescribed calcium citrate, which requires a less acidic environment for dissolution. Other common problems that occur in older adults that can significantly influence drug absorption include swallowing difficulties, poor nutrition, and dependence on feeding tubes.
Distribution
Aging can significantly alter drug distribution. With aging, adults experience a decline in muscle mass and a 20% to 40% increase in fat. The increase in body fat means lipid-soluble drugs have a greater volume of distribution, increased drug storage, reduced elimination, and a prolonged period of action. Older adults have a 10% to 15% reduction in total body water, which affects water-soluble drugs, and a 10% reduction in albumin. Reduced albumin levels can result in decreased protein binding of drugs and increased free drug available to exert therapeutic effects, but it also increases the risk for drug toxicity.
Metabolism
Hepatic blood flow in the older adult may be decreased by 40%; aging also results in a 15% to 30% decrease in liver size and a reduction in cytochrome P450 (CYP450) enzyme activity that is responsible for the breakdown of drugs. Drug clearance by hepatic metabolism can be reduced by these age-related changes. A reduction in hepatic metabolism can decrease first-pass metabolism and can prolong drug half-life, resulting in increased drug levels and potential drug toxicity. Nurses must be aware of these metabolic changes and must monitor response to drug therapy to avoid adverse reactions.
To assess liver function, liver enzymes must be checked. Elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) may indicate possible liver dysfunction. However, an older adult can have normal liver function test (LFT) results and still have impaired hepatic enzyme activity.
Excretion
Renal excretion of drugs decreases with age. Excretion is altered by age-related changes in kidney function, such as decreased renal size and volume, which differ for each individual. However, it is generally accepted that the GFR declines by 1 mL/min after the age of 40 (normal GFR is 100 to 125 mL/min). Despite a decline in kidney function, an individual’s creatinine may remain normal as he or she ages due to a decline in muscle mass and activity. Changes in kidney function affect many drugs, leading to a prolonged half-life and elevated drug levels. Changes in kidney function require dosage adjustment, especially if the drug has a narrow therapeutic range.
GFR can be calculated using the Cockroft-Gault formula, which is the formula recommended by the U.S. Food and Drug Administration (FDA) and therefore used by pharmaceutical manufacturers when determining dosage adjustments:
CCr=[(140−age)×weight)/(72×SCr)]×0.85(iffemale)
Abbreviations/Units: CCr (creatinine clearance) = mL/minute; Age = years; Weight = kg; SCr (serum creatinine) = mg/dL.
However, it can also be estimated by many calculators found on the Internet (www.globalrph.com/crcl.htm).
Nurses must have a general understanding of drug classifications that require dosage adjustment in patients with chronic kidney disease (CKD). The mnemonic BANDD CAMP (Table 6.1) may be helpful in remembering the drug classifications; however, nurses should not rely on their memory for drug administration. Package inserts, up-to-date drug reference books, and reputable websites (www.globalrph.com/index_renal.htm) maintain current dosing information.
Pharmacodynamics
Pharmacodynamic responses to drugs are altered with aging as a result of changes in the number of receptor sites, which affects the affinity of certain drugs. These changes are seen most clearly in the cardiovascular and central nervous systems.
Older adults experience a loss of sensitivity in adrenergic receptors, affecting both agonists and antagonists; this results in a reduced response to beta blockers and beta2 agonists. Older adults also experience a blunting in compensatory reflexes leading to orthostatic hypotension and falls.
With age, there is a reduction in dopaminergic and cholinergic receptors, neurons, and available neural connections in the brain. There is reduced blood flow to the brain, and the blood-brain barrier also becomes more permeable. This puts the older adult at risk for central nervous system (CNS) drug side effects, which include dizziness, seizures, confusion, sedation, and extrapyramidal effects.
Nursing Implications: Older Adult Drug Dosing and Monitoring
Polypharmacy
Polypharmacy refers to the use of more medications than is medically necessary. There is little agreement on the actual number of drugs that constitutes polypharmacy, but researchers use five drugs because this number has been associated with increased incidence of adverse drug reactions, geriatric syndromes, and increased mortality.
Risk factors associated with polypharmacy include advanced age, female sex, multiple health care providers, use of herbal therapies and OTC drugs, multiple chronic diseases, and the number of hospitalizations and care transitions. Polypharmacy can cause an increase in geriatric syndromes (cognitive impairment, falls, decreased functional status, urinary incontinence, and poor nutrition) as well as an increased incidence of adverse drug reactions and poor adherence.
Pharmacotherapy in older adults is complex. In order to reduce the risk for and incidence of polypharmacy, nurses must be involved in the coordination of care for older adults. Older adults should be encouraged to use only one pharmacy and should give the pharmacist a list of all the drugs taken—prescribed, herbal, and OTC. A properly informed pharmacist will be able to conduct a clinical review of the patient’s drugs to ensure the appropriateness of therapy. A pharmacist can also confirm patient understanding of individual therapy and can monitor responses to drug therapy. All of this is done to improve the overall quality of life of patients in their care.
Beers Criteria for Potentially Inappropriate Medication Use in Older Adults
The American Geriatrics Society Beers Criteria for Potentially Inappropriate Medication Use in Older Adults is a document developed by a consensus panel of 12 experts in geriatric care to aid health care providers in the safe prescription and administration of drugs to older adults (available free from http://onlinelibrary.wiley.com/doi/10.1111/jgs.13702/epdf). First developed in 1991, it has been revised four times, most recently in 2015. The 2015 Beers Criteria added new information on renal dosing of drugs and drug-drug interactions; as in previous editions, it continues to provide safety information based on best available evidence to use in decision making for drug therapy. Although the document provides information on drugs to avoid in older adults and drugs to use with caution, it is not designed for use in isolation. All drug therapy decisions should be made taking into consideration an individual’s preferences, values, and needs. It is very important that the nurse advocate for the patient in these areas to ensure safety and promote adherence.
TABLE 6.2
Barriers to Effective Drug Use by Older Adults
| Causes | Nursing Actions |
| Taking too many drugs at different times | Develop a chart indicating times to take drugs. Provide space to place a mark for each drug taken. Coordinate the drug regimen with activities of daily living (e.g., meals) and events. Use an organizer container (daily or weekly). Have the patient bring all drugs—including over-the-counter drugs and herbal, vitamin, and mineral supplements—to all health appointments. |
| Failure to understand the purpose or reason for a drug | Explain the purpose, drug action, and importance of the drug. Provide time for questions and reinforcement. Reinforce with written information. |
| Impaired memory | Encourage family members or friends to monitor the patient’s drug regimen. |
| Decreased mobility and dexterity | Advise family members or friends to have drugs and water or other fluid accessible and to assist older adults as needed. |
| Visual and hearing disturbances | Suggest eye and ear examinations (glasses or hearing aids). |
| High cost of prescriptions | Contact the social services department of your institution and compassionate care programs as appropriate. |
| Childproof drug bottles | Suggest that the patient request nonchildproof bottle caps. |
| Side effects or adverse reactions from the drug | Educate the patient and family about side effects to report to the health care provider. |
Adverse Drug Events
No drug is safe. Every year, over 775,000 emergency department (ED) visits occur due to adverse drug events (ADEs), and over 125,000 people are hospitalized due to ADEs. Older adults are twice as likely as younger adults to visit the ED with adverse drug events and are seven times as likely to be hospitalized. Most visits and hospitalizations occur due to reactions to blood thinners, drugs used to treat diabetes and seizures, cardiac drugs, and drugs used for pain control.
According to the World Health Organization, ADEs are “unintended and undesired effects of a [drug] at the normal dose.” There are five types of adverse drug events: (1) adverse drug reactions, (2) medication errors, (3) therapeutic failures, (4) adverse drug withdrawal events, and (5) overdoses. Older adults have multiple risk factors for ADEs, including frailty, multiple comorbidities, polypharmacy, and cognitive issues.
Adherence
Adherence to a drug regimen is a problem for all patient age groups, but it is especially troublesome in older adult patients. Older adults may fail to ask questions during interactions with health care providers, which leads to the drug regimen not being fully understood or precisely followed. Failure to adhere to a drug regimen can cause underdosing or overdosing that could be harmful to the patient’s health. Table 6.2 lists barriers to effective drug use by older adults.
Failure to adhere to a drug regimen can lead to ADEs, resulting in hospital admission, readmission to health care institutions, and even death. Complex drug regimens may be difficult for older adults to follow. Education is the cornerstone of adherence, and this includes education of the patient, family, and formal and informal caregivers.
Working with older adult patients is an ongoing nursing responsibility. The nurse should plan strategies with the patient and family or friends to encourage adherence with prescribed regimens. Daily contact may be necessary at first. Simply ordering the drug does not mean that the patient is able to get the drug or take it correctly. Older adults should have their prescriptions filled at one pharmacy if possible so a relationship can be established with a pharmacist and drug interactions can be identified and monitored closely.
The Medicare Modernization Act of 2003 made it possible for older adults to obtain prescription drug coverage through Medicare, with initial enrollment beginning in 2006. Older adults who are eligible for Medicare Part A or Part B are eligible for the optional Medicare Prescription Drug Plan (Part D) or coverage through a Medicare Advantage Plan (Part C). Each of these plans has its own formulary, copay rate, and in-network pharmacies. No plan is perfect for every older adult; the nurse, as advocate, must be able to assist the older adult to find the plan that is right for him or her and to make the most of the policy.
However, not all older adults have insurance that includes prescription drug coverage, nor are they able to afford their drugs even with insurance. Nurses need to assess the patient’s ability to obtain prescriptions prior to sending the patient home. Options for assistance are available, and the nurse can assist patients in navigating the system to obtain their drugs for free or at a reduced cost (see Partnership for Prescription Assistance at www.pparx.org and Extra Help at www.ssa.gov/medicare/prescriptionhelp).
Health care professionals—nurses, pharmacists, and health care providers—need to work collaboratively to enhance safety and adherence of older adult patients and to avoid errors and unwarranted concerns. Nurses are in a unique position to educate patients and to monitor the effectiveness of therapeutic regimens. A handout of tips for patients on talking with their pharmacist can be found at www.fda.gov/downloads/Drugs/ResourcesForYou/UCM163349.pdf.
Health Teaching with the Older Adult
Specific factors that enhance educational readiness and promote adherence in the older adult include the following:
• Ensure that the patient is wearing eyeglasses and has working hearing aids in place if needed. Check sensory aids to be sure they are clean and working.
• Speak in a tone of voice that the patient can hear; sit facing the patient, and limit distractions.
• Treat the patient with respect; never infantilize (also referred to as “elderspeak”); expect that the patient can learn.
• Review all drugs at each patient visit; ask the patient to bring all drugs to each appointment, and advise use of only one pharmacy.
• Advise the patient to complete the vial of life (medical information for emergency personnel to use in the provision of care; www.vialoflife.com) and keep it on the refrigerator door where safety personnel will know to look for it.
• Instruct the patient to keep a list of all drugs taken, bring it to all health appointments, and carry it when out of the house.
• Encourage a simple dosing schedule when possible.
• Suspect recently prescribed drug(s) if new confusion or disorientation occurs.
• Encourage the patient to report if a drug is not improving the condition for which it was prescribed.
• Consider use of memory aids such as pill organizers or planners, alarms, blinking lights, or prerecorded messages.
The National Institutes of Health (NIH) websites on aging are excellent resources for both health care providers and older adults and their families. The website for health care providers is www.nia.nih.gov; it has sections on health information, research, grants, training, news, and events. The website for older adults is www.nihseniorhealth.gov.
Nursing Process: Patient-Centered Collaborative CareGeriatrics
Assessment
• Assess for allergies.
• Assess for sensory and cognitive barriers.
• Assess the patient’s use of eyeglasses, and check the date of the last eye examination.
• Is the patient confused or disoriented? If so, is this state transitory?
• Assess laboratory test results, and follow up as appropriate.
• Decreased kidney and liver function can increase the half-life of drugs.
• Assess weight and vital signs.
• Determine all drugs the patient takes, including illicit, prescription, and OTC drugs and supplements.
• Assess patient adherence to the drug regimen.
• Assess patient knowledge of the purpose of each drug, how it works, and its possible side effects.
• Discern whether the patient has difficulty opening drug containers and whether the patient is experiencing side effects or adverse reactions.
• Discern whether the patient lives alone, with or without social support, and if assistance is needed with drugs, including costs or the transportation to acquire them.
• Obtain a history of chronic conditions.
Nursing Diagnoses
• Health Maintenance, Ineffective related to lack of, or alteration in, communication skills (written, verbal, and nonverbal)
• Therapeutic Regimen Management, Ineffective related to the complexity of the regimen
• Knowledge, Deficient related to cognitive limitation, information misinterpretation, and lack of interest in learning
• Constipation, Risk for related to use of drugs (e.g., aluminum-containing antacids, anticholinergics, calcium channel blockers, diuretics, and opiates)
Planning
• The patient will collaborate with health care providers to develop a therapeutic regimen that is congruent with health goals and lifestyle.
• The patient will describe why the drug is needed, how the drug is administered, common adverse reactions, and drug interactions.
• The patient will identify measures to prevent constipation.
• The patient will list resources that can be used for more information or support.
• The patient will verbalize the ability to manage the therapeutic regimen.
Nursing Interventions
• Ascertain whether financial problems are preventing the patient from purchasing prescribed drugs. Assistance programs are available.
• Communicate with the pharmacist or health care provider when a drug dose is in question. Check drug references for recommended drug dosages for older adults.
• Establish a collaborative partnership with the patient in order to meet health-related goals.
• Monitor the patient’s laboratory results to ensure that blood urea nitrogen (BUN), serum creatinine, estimated glomerular filtration rate (eGFR), and liver enzymes are within normal range and that drug levels are within the therapeutic range. Discuss findings with the health care provider.
• Observe the patient for adverse reactions when multiple drugs are being taken.
• Recognize a change in usual behavior or an increase in confusion. One of the first signs of drug toxicity is a change in mental status. Report changes to the health care provider.
• Remind the patient and family to tell the pharmacist about OTC preparations the patient is taking when picking up prescriptions.
Patient Teaching
General
• Advise patients and family to request a non–childproof cap from the pharmacy if the patient has arthritis in the hand joint or has difficulty opening childproof bottle caps. The patient may need to sign for this at the pharmacy, and safety of children or pets in the environment must be ensured.
• Advise patients to use one pharmacy to fill prescriptions, and instruct them to inform the pharmacist of all illicit, prescription, and OTC drugs and supplements taken.
• Be available to answer patient questions. Be supportive of the older adult and the family. Discuss problems related to the drugs.
• Counsel patients not to share prescribed drugs with others or to take drugs prescribed for another person.
• Explain to patients and family the importance of adherence to the drug regimen. Emphasize the importance of taking drugs as prescribed.
• Review drugs with patients and family, including the reason the drug was prescribed, route of administration, frequency, common side effects, and when to notify the health care provider.
Cultural Considerations• Do not assume that lack of eye contact means the patient is not listening or does not care; it might indicate respect. More traditional or older individuals in some cultures do not maintain eye contact.
• Provide additional time for verbal and written explanations to ensure all questions related to the drug regimen have been asked and answered. This will promote adherence.
• Recognize that language difficulties may interfere with older adults’ understanding of the prescribed drug regimen if English is not their first language; provide educational material in the patient’s native language.
Evaluation
• Evaluate adherence to the drug regimen, and answer any questions the older adult may have.
• Evaluate therapeutic drug response, and ascertain side effects or adverse reactions.
Critical Thinking Case Study
A 78-year-old woman comes to the clinic for a new-patient examination. She reports that she smokes Cannabis several times a week and also takes alprazolam 0.5 mg three times per day, a combination tablet of metoprolol tartrate 50 mg/hydrochlorothiazide 25 mg daily, aspirin 81 mg daily; garlic soft-gels 1000 mg twice a day; and ibuprofen 400 mg four times a day.
1. Do any of these drugs appear on the 2015 American Geriatrics Society Beers Criteria for Potentially Inappropriate Medication Use in Older Adults? If so, what do the criteria say about them?
2. What interactions exist among the drugs and supplements this patient is taking?
3. What is the evidence for taking garlic to reduce cholesterol?
