Hospital admission because of drug-related problems 'are most prevalent in the elderly.1 The proportion of reports of adverse drug reactions received lor the elderly rose between 1965 and 1983, and the increased use of drugs is correlated with a corresponding climb in the number of adverse drug reactions.2,3 Drug reactions are generally related to the influence of age, toxicity, side effects, immunologic reactions, idiosyncratic reactions, drag drug interactions, and drug disease interactions. This article explores -the incidence of drug-related iatrogenesis in the elderly and corresponding nursing iniejyentions to prevent these problems.
Drug reactions from normal therapeutic dosages of medications can result from age-associated changes in pharmacodynamics, the response of body receptors to a drug and its effects, and pharmacokinetics, which is the absorption, distribution, metabolism, and excretion of drugs in the body. It is well documented that the elderly respond differently to drugs than do younger people.4"7 Physiological changes in aging that affect drug use are summarized in Table 1.
The prevalence of drug-related problems in the elderly is reflected in statistics related to the amount of drugs consumed. For example, approximately three fourths of community dwelling ambulatory persons over age 65 take at least one prescription medication. They consume 12 to 15 daily medications on average, including over-thecounter-drugs.8-9 Twenty-five percent to thirty-one percent of all medications are taken by the elderly, who comprise only 12% of the total population, and the elderly experience 30% of all adverse drug reactions.810 An average of 9. 1 medications are taken by hospitalized elderly,11 and on average between three and six drugs are taken by those in long-term care facilities.12·13 Of those in long-term care facilities, it is estimated that one third of the residents receive from 8 to 16 drugs daily.14 The most common medications prescribed for elders in long-term care facilities are phenothiazines and psychotropic drugs;1213 cardiotonics, especially digitalis; diuretics; analgesics; and gastrointestinal medications.12
Adverse drug reactions are 2'/2 times greater in persons over age 60, 15 and psychoactive drugs are most commonly associated with those adverse drug reactions. In a recent study of rest homes in Massachusetts, researchers found that 55% of the residents were taking a minimum of one psychoactive medication.16 Of these, 39% were taking antipsychotic medications, with 1 8% taking two or more of these medications. Tragically, physician participation in drug decisions was evident in less than half of the residents in a follow-up study. Thirty-three percent of these residents had serious cognitive impairment as shown by mental status tests, and 6% had symptoms of moderate to severe tardive dyskinesia, a tragic side effect of antipsychotic medications. Staff knowledge of the purpose and adverse effects of such drugs was minimal.16
As stated previously, drug-related hospitalizations are more prevalent in the elderly.17·18 Incorrect self-administration of drugs is another cause of drug reactions. This includes omission of drugs, taking another's prescriptions, and use of over-the-counter drugs, as well as the removal of drugs when admitted to long-term care19 and medication errors.20 One study showed mat more than 50% of elderly patients failed to take their medications as prescribed after hospital discharge.21 Another investigation reported that only 22% of prescription medications were taken as ordered, and 31% were taken in such a manner as to seriously compromise the health of the individuals for whom they had been prescribed.21
As noted earlier, polypharmacy is a common problem with the elderly. For example, if an elderly client is taking four different drugs, the risk of adverse reactions is 20%; with five drugs, the risk increases to 30%; with six drugs, the risk escalates to 40%. Seventy percent of the drugs taken in long-term care facilities can be grouped into six categories: psychotropics, cardiovascular agents, laxatives, analgesics, vitamins, and diuretics.22
Signs of drug toxicity or adverse reactions include a change in mental functioning,23 changes in gait, insomnia or drowsiness, visual changes, slurred speech, ototoxicity (affecting function of the eighth cranial nerveX seizures, tremors, irritability, and anticholinergic effects such as dry mouth, constipation, blurred vision, urinary retention, headache, and restlessness. In a study of 300 patients who were evaluated for cognitive impairment, benzodiazepines (eg, Valium) were most commonly implicated.24 Researchers also found a strong association between adverse drug reactions in die cognitively impaired elderly and the number of drugs used, use of sedative hypnotics, and antihypertensives.
AGE-ASSOCIATED CHANGES AFFECTING DRUG USE
RISK FACTORS FOR TARDIVE DYSKINESIA*
Digitalis toxicity is one of the most common adverse drug reactions encountered in the elderly.25 Generally, the elderly person can be maintained on as little as 0.065 mg per day, yet the most common dosage forms are 0.125 and 0.25.25 Furthermore, it is estimated that maintenance digoxin therapy is probably unnecessary in about 70% of cases.26 Common signs of digitalis toxicity are gastrointestinal (anorexia, nausea, vomiting, diarrheaX central nervous system (headache, weakness, apathy, visual disturbances, such as blurred, yellow, or green vision and halo effect), and cardiac disturbances (ventricular tachycardia, premature ventricular contractions, and excessive slowing of the heart rate).27 Ventricular fibrillation is the most common cause of death from digitalis intoxication.27 Immediate cessation of the drug must occur if the patient experiences paroxysmal atrial or ventricular tachycardia, which are manifested by palpitations, rapid pulse, and an abnormal electrocardiogram.
Many elders taking digitalis preparations are also taking diuretics. This increases the incidence of hypokalemia, and the likelihood of digitalis intoxication is also increased. Gerontologie nurses must be aware of the need to monitor vital signs of persons taking digitalis preparations as well as laboratory values, and more diligently monitor those taking both digitalis and diuretics.
The profile of the person most likely to suffer from adverse drug reactions is a 75-year-old small woman with a history of allergic or adverse reactions. Typically, the "at risk" patient may have multiple chronic illnesses, dysfunction of the kidney or liver, is taking more than five drugs, some of which are considered "high risk," and has experienced a change in overall physical condition, including mental status (Weitzel EA. 1988. Unpublished data). Drugs categorized as "high risk" include the benzodiazepines, cimetadine, digitalis, furosemide, gentamicin, Lrdopa, lithium, methyldopa, nonsteroidal anti-inflammatory drugs (NSAIDs), phenothiazide tranquilizers, phenytoin, procainamide, ranitidine, sulfonylureas, theophylline, and tricyclic antidepressants.28"30 This by no means precludes the possibility of adverse reactions by nonprescription drugs, such as aspirin.
Adverse side effects commonly reported include anticholinergic effects related to tricyclic antidepressants, hypokalemia associated with use of diuretics, and gingival hyperplasia associated with phenytoin. Tardive dyskinesia (TD) is a well-known and potentially dangerous side effect of antipsychotic drugs, especially in the elderly. TD is a complex syndrome manifested by hyperkinetic involuntary movements of the mouth, lips, and tongue. The patient may drool, appear to chew on tongue or cheek, or exhibit sucking or smacking of the lips. Prevalence of tardive dyskinesia in chronic antipsychotic-treated patient populations in studies after 1975 has been estimated to be as high as 20% to 35%.31 The incidence of tardive dyskinesia as estimated by the Task Force Report of the American Psychiatric Association is 10% to 20% of patients at risk, but other studies have found it to be as high as 27%32 and 57%.33 More recently, tardive dyskinesia has been associated with the use of metoclopramide (Reglan).34 Risk factors for TD are summarized in Table 2.
For two thirds of patients, TD symptoms may persist for at least 3 months after discontinuation of the antipsychotic, and improvement may be seen up to 3 years following discontinuation of the medication (Jeste DV. 1987. Unpublished manuscript). Importantly for gerontologie nurses, TD can be prevented by early detection of the movements associated with this side effect. A number of assessment scales have been developed to detect TD: the Abnormal Involuntary Movement Scale,35 the Simpson-Rockland Dyskinesia Rating Scale,36 the Smith-TRIMS Tardive Dyskinesia Scale,37 and the Dyskinesia Identification System-Coldwater.38 Treatment begins with early detection by carefully monitoring patients on antipsychotic medication and regular assessment using one of the scales mentioned above.39
Side effects of antipsychotic drugs are well-known, and the use of these medications is specifically addressed in drafts of the Omnibus Budget Reconciliation Act (OBRA) interpretive guidelines. These side effects have potentially serious consequences for the elderly and include sedation, predisposing the elder to falls and physical dependence; extrapyramidal symptoms (including pseudoparkinsonismX causing changes in ambulation and selfcare abilities because of tremors. dystonias, etc; akathisia (a subjective experience of motor restlessness), which may result in overprescription of the medication because of an inability of the client to sit or stand still or a compulsion to pace; anticholinergic effects, including dry mouth and urinary retention; and orthostatic hypotension, contributing to dizziness and falls.27 The degree of these side effects varies with the specific drug and dosage. Care and diligence, along with proper prescriptions, leads to safer and more effective use of antipsychotic drugs.
In a 17-year study of 3,521 cases, NSAIDs were shown to cause dermatologie side effects (39%); gastrointestinal reactions (25%); neurologic and mental reactions (fewer than 10%); hematologic adverse reactions (7%); endocrine, metabolic, and nutritional adverse effects (6%); hepatic reactions (3%); renal and urinary tract adverse reactions (fewer than 3%); cardiovascular reactions (2%); respiratory symptoms (1.5%); and allergic reactions (1.5%).40 Drugs implicated in this study include butylphrazolidin derivatives (eg, phenlybutazone), indol derivatives (eg, indomethacin), propionic acid derivatives (eg, Ibuprofen, naproxen), anthranilic acid derivatives (tolfenamic acid), benzotriazin derivatives, and others such as benzydamine, diclofenac, sulindac, proquazone, tolmetin, piroxicam. Because of ageassociated changes cited previously as well as polypharmacy, the elderly are at particular risk of experiencing these side effects.
Immunologic and Idiosyncratic Reactions
Immunologic reactions, or allergies, are common adverse drug reactions in the general population.41 Drug allergies are commonly experienced with antibiotics, especially penicillin and sulfa drugs, and aspirin. It is important for gerontologie nurses to take an accurate and thorough drug history to determine the presence of allergies.
Idiosyncratic reactions are rare and unpredictable. An example of an idiosyncratic reaction is agranulocytosis associated with chloramphenicol. The gerontologie nurse should thoroughly observe the effects of any drug, especially those newly prescribed, and take note of changes in behavior, physical condition (including laboratory testsX and mental status. If the nurse suspects an idiosyncratic reaction, the physician should be notified for further direction. It is also advantageous to use the services of a pharmacist who can assist in determining if an idiosyncratic reaction has occurred.
Drug- Drug Interactions
The most common of all adverse drug reactions, accounting for 22% of patients in one rehabilitation hospital, are the consequences of drug-drug interactions.42 In addition, secondary effects are common, such as druginduced parkinsonism caused by administration of haloperidol (Haldol). Haldol has also been associated with radial nerve palsy in three elderly demented women who were confined to chairs for most of the day.43 When the Haldol was discontinued and physical measures applied, the women improved.
The most commonly seen drug-drug interaction is in persons taking a digitalis preparation with a diuretic. Other potential drug-drug interactions include tetracycline-iron or antacids (reduce the absorption of tetracycline), cephaloridine-furosemide (nephrotoxicity), and gentamicin-ethacrynic acid (ototoxicity).44 In a study of 573 charts of elderly patients, Gosney and Tallis found 133 prescriptions with the potential for drug-drug interactions.45 Most striking were furosemide-aminoglycoside (ototoxicity, nephrotoxicity), furosemide-cephalosporin (nephrotoxicity), and furosemide-prednisolone (hypokalemia).45 Factors that may contribute to drug interactions are the use of more than one medication; ingestion of alcohol with medications; concurrent self-medication with nonprescription drugs; treatment by more than one physician; and purchase of drugs in more than one pharmacy.46
Drug-disease interactions are also common. Bor example, persons with renal disease can develop excessive narcosis even with standard doses of morphine.47 Confusion, agitation, tremor, myoclonus, or seizures can result from the use of meperidine (Demerol) in persons with renal disease.48 Some cases of congestive heart failure may be due to the use of NSAIDs in the elderly.49 In persons with hepatic disease, bioavailability is enhanced and clearance is decreased when taking analgesics such as pethidine, pentazocine, and salicylamide.50 With acute cardiogenic pulmonary edema, theophylline has a prolonged serum half-life.51 Phenytoin-induced hypotension has been seen in elderly seizure patients.52 Changes in renal, hepatic, and cardiovascular functioning have the most potential to affect drug therapy.53 Other conditions that gerontologie nurses should be aware of that can cause drugdisease interactions are arthritis, diabetes mellitus, prostatic hypertrophy, hypertension, upper respiratory tract infection, urethritis, and psychiatric illness.46
NURSING IMPLICATIONS: EDUCATION AND PRACTICE
Iatrogenic drug reactions can be devastating for the elderly, whether they are institutionalized or community dwelling, and may affect both quality of life and independence. However, there are many opportunities for gerontologie nurses to predict and prevent the potentially drastic consequences of adverse drug reactions.
Education is an important first step. One study of 32 pharmacists in geriatric practice reported that the most difficult problems associated with geriatric pharmacy were related to education and communication. Among the problems were lack of geriatric knowledge, patient compliance, physician overprescribing, and communication with the elderly.54 Inservice teaching for nursing home staff about adverse drug reactions has been shown to be an effective intervention.55 As a result of teaching, one study found that 10.8% of the medication orders were changed over a 3-month period, with 6% of the orders attributed to new knowledge about probable adverse drug reactions. In view of the scope of the problems associated with medications, it would behoove any institution, whether facility- or community-based, to educate persons working with the elderly on the effects and possible problems of drug administration in this population. Effective educational programs would also assist facilities in implementing OBRA '87 regulations regarding unnecessary drugs.
Educational approaches must include problem recognition associated with the aged that would affect drug use. Physicians, pharmacists, nurses, and ancillary personnel, as well as family and community members, should be knowledgeable of potential problems according to their level of involvement. Elderly persons themselves should not be overlooked in efforts to educate about proper medication usage and potential problems.
Drug review by the gerontological nurse in conjunction with a pharmacist is recommended for all who work with the elderly, and is mandated in nursing facilities. Thorough and conscientious drug review can anticipate and prevent problems associated with drug usage, such as drug-disease interactions, drug-drug interactions, changes in electrolytes, etc. It is important for the gerontological nurse or pharmacist to inform and educate the physician about potential problems and follow through on appropriate solutions.
The importance of a thorough and accurate drug history cannot be overstated. It is important to explore any history of allergies, usage of over-thecounter drugs, disease conditions, and patient knowledge regarding the purpose of drugs. In interviewing elders, it is important to determine in a nonjudgmental manner if they have been borrowing drugs or if they are using drugs correctly. Adverse reactions to a drug may merely reflect incorrect administration as a result of a knowledge deficit or financial constraints. It is important for gerontological nurses to understand that a variety of conditions may affect drug compliance, for example limited income or multiple chronic diseases with appropriate drug usage. It is not unusual for elders to spend $300 per month for drugs. When income is low, the elder may choose priorities other than prescribed medications.
Nursing measures should be instituted to alleviate symptoms and complaints commonly experienced by the elderly before the initiation of drug therapy. For example, backrubs, positioning, or warm milk should be tried to promote sleep or comfort rather than the use of sedative-hypnotics or even analgesics. Another example is the use of exercise and ambulation to alleviate mild dependent edema.
Gerontologie nurses are the most accessible health-care professionals to the elderly and are in an ideal position to recognize and limit problems associated with drug therapy. Nurses can take the lead through consultation with pharmacists, physicians, family, and community members to implement plans for effective drug use and quality of life for the elderly.
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AGE-ASSOCIATED CHANGES AFFECTING DRUG USE
RISK FACTORS FOR TARDIVE DYSKINESIA*