Avoiding Medication Mishaps: A Pharmacist's Perspective
by Bradley R. Williams, Pharm.D.| Geriatric Times |  |
May/June 2000 | |
Vol. I | |
Issue 1 |
The U.S. Census Bureau (1996 estimates that there are approximately 34.7 million people at least 65 years of age, and 4.25 million at least 85 years of age, living in the United States. This represents 12.6% and 1.6%, respectively, of the total population. By the year 2030, the percentages are anticipated to climb to 19.9% and 2.4%. This increased longevity, however, does not necessarily imply good health. Over 30% of people aged 65 to 74 years, and almost 45% of people aged 75 years and above, experience some form of disability. The National Center for Health Statistics reported the leading causes of death for older adults to include such chronic conditions as heart and cerebrovascular disorders, respiratory disorders, diabetes mellitus, and renal and hepatic diseases (Peters et al., 1998). One common thread among these conditions is the importance of pharmacotherapy in their management.
Medication-Related Problems
As the number of medications used increases, so does the likelihood that adverse drug reactions or interactions will occur. Several other factors also predispose geriatric patients to medication-related problems. These include age-associated changes in physiology and body composition, polymedicine, and noncompliance with medication regimens. As Gurwitz and Avorn pointed out in 1991, however, age per se is probably not a factor for medication-related problems.
Rho and Wong (1998) reviewed the relationship between age-associated physiologic changes and drug effects. They found changes in gastric acidity and gastrointestinal motility can slow drug absorption and delay drug action. Increased body fat, decreased body water and decreased serum albumin levels were found to modify the distribution patterns and to alter the duration of action or pharmacologic activity of several agents. In addition, they found the reduced activity of many hepatic enzyme systems and decreased renal function may increase the risk for drug interactions and slow the elimination of certain drugs.
Changes in drug responses occur because of several other factors, as well. Geriatric patients often are more susceptible than younger adults to central nervous system depressants. Reduced parasympathetic nervous system activity increases the likelihood that anticholinergic adverse effects will occur. The decline in the density of ß-adrenergic receptors reduces the effects of the most commonly used bronchodilators and may increase the risk for congestive heart failure in many patients who take ß-blockers. Reduced cardiac output and decreased total body water, combined with changes in baroreflexes, predispose older adults to hypotension and orthostatic effects of diuretics and antihypertensive agents. Finally, the reduced glucose tolerance that accompanies aging may lead to hyperglycemic effects from drugs such as diuretics and corticosteroid agents.
Many clinicians associate polymedicine with the use of more than a certain number of medications (e.g., five or more). Many geriatric patients, however, are medically stable on a certain number of medications, while others may have very complex reactions. Basing one's definition of polymedicine on a specific prescribed number of drugs can lead to either a false sense of security (e.g., a patient taking four medications but has only osteoarthritis that is managed with acetaminophen) or excessive concern (e.g., a patient taking a total of eight medications to treat diabetes mellitus, hyperlipidemia, coronary artery disease, hypertension, congestive heart failure and depression). A preferred view of polymedicine would include simply the use of unnecessary medications, independent of the number of drugs being taken. This definition relies on the linkage of medication use to specific problems and allows for more appropriate evaluation of a patient's drug regimen.
Several factors contribute to the development of polymedicine. The presence of multiple disease states often leads to the prescribing of several medications. The risk of adverse drug reactions or interactions increases with the number of medications; these adverse reactions may then need to be treated with additional medications.
The current state of health care practice also influences polymedicine. Clinicians have significant time constraints that inhibit their ability to fully consider all current problems and new complaints. The end result frequently is prescribing new medication; if more time were available, a different approach might have been taken. This effect is compounded by the presence of multiple clinicians who may not communicate with each other. As a result, any one physician may not have a complete list of all medications prescribed for a patient.
Patients, too, contribute to polymedicine. Older adults are the most frequent consumers of nonprescription medications and are increasingly turning to alternative medicines to self-treat disease symptoms. Many older adults rely on testimonials from friends or relatives, health store salespeople and advertising to help them choose the most "effective" remedy. In addition, direct-to-consumer advertising (including coupons) fuels the demand for prescription medications that are often new, expensive and not well-tested in the geriatric population.
Evidence of polymedicine is easier to identify when viewed from the perspective of drug need rather than the number of prescriptions. One should look for the presence of medications that do not have a specific indication. This may indicate the continued use of a medication that was appropriately prescribed, but is no longer needed. The use of duplicate medications (e.g., two antidepressants) or interacting drugs (such as a b-blocker and a b-agonist) represent opportunities to reduce the number of medications and improve therapeutic outcomes. While most clinicians may focus on medication doses that are too high, subtherapeutic doses typically indicate that medications are providing no therapeutic benefit. At times, adverse drug effects may not be fully appreciated as iatrogenic problems, and a new medication may be prescribed to treat that symptom.
Polymedicine and noncompliance frequently may be linked. A study published in 1990 by Col et al. found that 28% of hospital admissions for people age 65 and older were due to medication-related problems. Of those 89 admissions, 53 were due to adverse drug reactions and 36 were due to noncompliance. Difficulty recalling a medication regimen, multiple medications, multiple prescribers, female gender, moderate income and the perception that medications were expensive were predictors for noncompliance (Col et al., 1990). Fitten et al. reported in 1995 that diminished functional and cognitive capacities and increasing complexity of the medication regimen also predispose elderly patients to be noncompliant.
Close Monitoring
Avoiding medication mishaps in elderly patients requires effort in several areas. The first steps include identifying and avoiding the use of medications that present a high risk for adverse reactions and identifying patients who are more likely to experience therapeutic misadventures. In 1997, Beers published a consensus panel list of medications that are potentially inappropriate for older adults. Many of the agents on the list are older drugs that are not well-tolerated, present a high risk for toxicity, and are either no better than, or inferior to, newer pharmacological agents. Among these are long-acting benzodiazepines, some tricyclic antidepressants, propoxyphene (Darvon, Darvocet), pentazocine (Talacen, Talwin) and some older antihypertensive agents. Lists such as this should not be considered absolute; some medications generally considered inappropriate may be used effectively in certain situations. Conversely, drugs not appearing on a list may, in fact, be highly dangerous when used in some individuals.
Certain populations of elderly patients are at greater risk than others for developing medication-related problems. Williams et al. (1993) reviewed the use of medications among nursing home residents. Besides being users of large numbers of medications, nursing facility residents are frequently prescribed psychotropic and cardiovascular medications that predispose them to cognitive impairment, falls and other functional deficits. A study published by Williams et al. in 1999 found similar patterns among older adults living in residential facilities for the elderly. The combination of several medications, common use of psychotropic and cardiovascular drugs, and medical frailty indicates that this population's medication use requires very close monitoring. In any environment, patients with multiple diseases are at high risk for medication problems because of the frequent use of many medications and the likelihood that several practitioners may be prescribing medications without the full knowledge of any other concurrent medication use by the patient. Frail older adults are at risk for overdosage, particularly when drugs with a narrow therapeutic index are prescribed. Depressed patients often have multiple somatic complaints that may be individually treated, either with prescribed or over-the-counter medicines. Patients with dementia are unreliable historians who cannot provide accurate information regarding compliance or self-treatment.
Clinician Strategies
The risk for medication mishaps can be minimized by incorporating the following simple strategies into geriatric patients' office visit routines:
- Maintain a problem list that links medications to specific problems. Any drugs not linked to a current problem can be discontinued. Some agents may be used to treat or prevent problems associated with other medications (e.g., potassium supplements with diuretics). When the primary agent is discontinued, this will ensure that the secondary drug also is stopped.
- Identify problems that will benefit from pharmacotherapy, may be adversely affected by other drugs or can influence the therapy of concurrent diseases. Some disorders, such as claudication, may respond better to nondrug treatments (e.g., physical therapy and exercise). The use of a ß-blocker to treat heart disease can exacerbate bronchospasm in patients with reactive airway disease. For most diseases, alternative treatments that do not adversely affect concurrent problems can be identified and used.
- Avoid prescribing solely to symptoms. Incontinence, pain, gastrointestinal complaints and many other symptoms may be manifestations of an underlying problem. This may be particularly true with urinary tract infections, mood disorders and other problems often characterized by nonspecific complaints.
- Frequently re-evaluate therapy and review medications at each visit. Patients may forget one or more medications that they are using, or they may be taking medications prescribed by other clinicians or purchased without a prescription. If all medications are brought in during an office visit, an accurate picture is available and an estimate of compliance can be made. At the very least, patients should be encouraged to bring with them a current list of all their medications, including nonprescription products, vitamins and alternative medicines.
- The primary care physician should coordinate care. Because these physicians will probably see the patient most frequently, they are in the best position to coordinate activities among physicians and other prescribers. They also provide a point of initial contact for patients when new problems arise.
- Encourage the use of a single pharmacy. Because most pharmacies maintain patient medication profiles, the use of a single pharmacy ensures that one location will have a record of all medications being taken by an older patient. It is likely that nonprescription remedies will be purchased at the same place. When the pharmacist identifies a potential adverse reaction or drug interaction, the appropriate prescriber(s) can be contacted. The pharmacist also can evaluate and recommend nonprescription products or refer the patient back to the primary physician, when appropriate.
Dr. Williams is associate professor of clinical pharmacy and clinical gerontology at the University of Southern California School of Pharmacy and Andrus Gerontology Center in Los Angeles.
References
Beers MH (1997), Explicit criteria for determining potentially inappropriate medication use by the elderly. An update. Arch Intern Med 157(14):1531-1536.
Col N, Fanale JE, Kronholm P (1990), The role of medication noncompliance and adverse drug reactions in hospitalizations of the elderly. Arch Intern Med 150(4):841-845.
Fitten LJ, Coleman L, Siembieda DW et al. (1995), Assessment of capacity to comply with medication regimens in older patients. J Am Geriatr Soc 43(4):361-367.
Gurwitz JH, Avorn J (1991), The ambiguous relation between aging and adverse drug reactions. Ann Intern Med 114(11):956-966.
Peters KD, Kochanek KD, Murphy SL (1998), Deaths: Final Data for 1996. National Vital Statistics Reports; vol. 47 no. 9. Hyattsville, Md.: National Center for Health Statistics, pp22, 28.
Rho JP, Wong FS (1998), Principles of prescribing medications. In: Practical Ambulatory Geriatrics, 2nd ed., Yoshikawa TT, Cobbs EL, Brummel-Smith K, eds. St. Louis, Mo.: Mosby-Year Book Inc., pp19-25.
U.S. Bureau of the Census (1996), Resident population of the United States: Middle series projections, 1996-2050.
Williams BR, Nichol MB, Lowe B et al. (1999), Medication use in residential care facilities for the elderly. Ann Pharmacother 33(2):149-155.
Williams BR, Thompson JF, Brummel-Smith KV (1993), Improving medication use in the nursing home. In: Improving Care in the Nursing Home: Comprehensive Reviews of Clinical Research, Rubenstein LZ, Wieland D, eds. Newbury Park, Calif.: Sage Publications, pp33-64.