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Drug-Related Problems in the Elderly

by J. Mark Ruscin, PharmD, Sunny A. Linnebur, PharmD, FCCP, BCPS, CGP

Drug-related problems are common in the elderly and include drug ineffectiveness, adverse drug effects, overdosage, underdosage, and drug interactions.

Drugs may be ineffective in the elderly because clinicians underprescribe (eg, because of increased concern about adverse effects) or because adherence is poor (eg, because of financial or cognitive limitations).

Adverse drug effects are effects that are unwanted, uncomfortable, or dangerous. Common examples are oversedation, confusion, hallucinations, falls, and bleeding. Among ambulatory people 65, adverse drug effects occur at a rate of about 50 events per 1000 person-years. Hospitalization rates due to adverse drug effects are 4 times higher in elderly patients (about 17%) than in younger patients (4%).

Reasons for Drug-Related Problems

Adverse drug effects can occur in any patient, but certain characteristics of the elderly make them more susceptible. For example, the elderly often take many drugs (polypharmacy) and have age-related changes in pharmacodynamics and pharmacokinetics; both increase the risk of adverse effects.

At any age, adverse drug effects may occur when drugs are prescribed and taken appropriately; eg, new-onset allergic reactions are not predictable or preventable. However, adverse effects are thought to be preventable in almost 90% of cases in the elderly (compared with only 24% in younger patients). Certain drug classes are commonly involved: antipsychotics, warfarin, antiplatelet agents, hypoglycemic drugs, antidepressants, and sedative-hypnotics.

In the elderly, a number of common reasons for adverse drug effects, ineffectiveness, or both are preventable (see Preventable Causes of Drug-Related Problems). Several of these reasons involve inadequate communication with patients or between health care practitioners (particularly during health care transitions).

Preventable Causes of Drug-Related Problems



Drug interactions

Use of a drug results in a drug-drug, drug-food, drug-supplement, or drug-disease interaction, leading to adverse effects or decreased efficacy.

Inadequate monitoring

A medical problem is being treated with the correct drug, but the patient is not adequately monitored for complications, effectiveness, or both.

Inappropriate drug selection

A medical problem that requires drug therapy is being treated with a less-than-optimal drug.

Inappropriate treatment

A patient is taking a drug for no medically valid reason.

Lack of patient adherence

The correct drug for a medical problem is prescribed, but the patient is not taking it.


A medical problem is being treated with too much of the correct drug.

Poor communication

Drugs are inappropriately continued or stopped when care is transitioned between providers and/or facilities.


A medical problem is being treated with too little of the correct drug.

Untreated medical problem

A medical problem requires drug therapy, but no drug is being used to treat that problem.

Drug-disease interactions

A drug given to treat one disease can exacerbate another disease regardless of patient age, but such interactions are of special concern in the elderly. Distinguishing often subtle adverse drug effects from the effects of disease is difficult (see Drug-Disease Interactions in the Elderly (Based on the American Geriatrics Society 2012 Beers Criteria Update)) and may lead to a prescribing cascade.

A prescribing cascade occurs when the adverse effect of a drug is misinterpreted as a symptom or sign of a new disorder and a new drug is prescribed to treat it. The new, unnecessary drug may cause additional adverse effects, which may then be misinterpreted as yet another disorder and treated unnecessarily, and so on.

Many drugs have adverse effects that resemble symptoms of disorders common among the elderly or changes due to aging. The following are examples:

  • Antipsychotics may cause symptoms that resemble Parkinson disease. In elderly patients, these symptoms may be diagnosed as Parkinson disease and treated, possibly leading to adverse effects from the antiparkinson drugs (eg, orthostatic hypotension, delirium, nausea).

  • Cholinesterase inhibitors (eg, donepezil) may be prescribed for patients with dementia. These drugs may cause diarrhea or urinary incontinence. Patients may then be prescribed an anticholinergic drug (eg, oxybutynin) to treat the new symptoms. Thus, an unnecessary drug is added, increasing the risk of adverse drug effects and drug-drug interactions. A better strategy is to reduce the dose of the cholinesterase inhibitor or consider a different treatment for dementia (eg, memantine) with a different mechanism of action.

In elderly patients, prescribers should always consider the possibility that a new symptom or sign is due to drug therapy.

Drug-Disease Interactions in the Elderly (Based on the American Geriatrics Society 2012 Beers Criteria Update)



Possible Adverse Effects


Heart failure

Cilostazol, COX-2 inhibitors,dronedarone, nondihydropyridine Ca channel blockers* (diltiazem, verapamil), NSAIDs, pioglitazone, rosiglitazone

May promote fluid retention and exacerbate heart failure


Acetylcholinesterase inhibitors, chlorpromazine, peripheral α-blockers (doxazosin, prazosin, terazosin), tertiary TCAs, thioridazine, olanzapine

Increased risk of orthostatic hypotension or bradycardia


Chronic seizures or epilepsy

Bupropion, chlorpromazine, clozapine, maprotiline, olanzapine, thioridazine, thiothixene, tramadol

Lowered seizure threshold

Possibly acceptable in patients with well-controlled seizures in whom alternative agents have not been effective


All TCAs, benzodiazepines, drugs that have anticholinergic effects, chlorpromazine, corticosteroids, H 2 receptor blockers, meperidine, sedative hypnotics, thioridazine

Worsened delirium in older adults with or at high risk of delirium

If discontinuing drugs used chronically, taper to avoid withdrawal symptoms

Dementia and cognitive impairment

Antipsychotics (chronic and as-needed use), benzodiazepines, drugs that have anticholinergic effects, H 2 receptor blockers, zolpidem

Adverse CNS effects

For antipsychotics, increased risk of stroke and mortality in patients with dementia

History of falls or fractures

Anticonvulsants, antipsychotics, benzodiazepines, nonbenzodiazepine hypnotics (eszopiclone, zaleplon, zolpidem), TCAs, SSRIs

Ataxia, impaired psychomotor function, syncope, and additional falls; shorter-acting benzodiazepines are not safer than long-acting ones

Can be used if safer alternatives are not available

Avoid anticonvulsants except for seizure disorders


Oral decongestants (pseudoephedrine, phenylephrine), stimulants (amphetamine, methylphenidate, pemoline), theobromines (theophylline, caffeine)

CNS stimulant effects

Parkinson disease

Antiemetics (metoclopramide, prochlorperazine, promethazine), antipsychotics (except for quetiapine and clozapine)

Dopamine receptor antagonists with potential to worsen parkinsonian symptoms (less likely with quetiapine and clozapine)


Chronic constipation

Drugs that have antispasmodic and anticholinergic effects (antipsychotics, belladonna alkaloids, clidinium-chlordiazepoxide, dicyclomine, hyoscyamine, propantheline, scopolamine, tertiary TCAs [amitriptyline, clomipramine, doxepin, imipramine, and trimipramine]), first-generation antihistamines (brompheniramine carbinoxamine, chlorpheniramine, clemastine , cyproheptadine, dexbrompheniramine,dexchlorpheniramine , diphenhydramine, doxylamine, hydroxyzine, promethazine, triprolidine), nondihydropyridine Ca channel blockers (diltiazem, verapamil), oral antimuscarinics for urinary incontinence (darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine, trospium)

Can worsen constipation; agents for urinary incontinence: antimuscarinics overall differ in incidence of constipation; response variable; consider alternative agent if constipation develops

History of gastric or duodenal ulcers

Aspirin (> 325 mg/day), non–COX-2 selective NSAIDs

Exacerbate existing ulcers or cause new ulcers

Avoid unless other alternatives are not effective and patients can take a gastroprotective drug (eg, a proton pump inhibitor or misoprostol)

Kidney and Urinary Tract

Chronic kidney disease (stages IV and V)

NSAIDs, triamterene

Increased risk of kidney injury

Urinary incontinence (all types) in women

Estrogen, oral and transdermal (excludes intravaginal estrogen)

Worsened incontinence

Lower urinary tract symptoms, benign prostatic hyperplasia

Drugs that have strong anticholinergic effects (except antimuscarinics for urinary incontinence), inhaled agents that have anticholinergic effects

May decrease urinary flow and cause urinary retention in men

Stress or mixed urinary incontinence

α-Blockers (doxazosin, prazosin, terazosin)

Worsened incontinence in women

*Avoid only in patients who have systolic heart failure.

COX-2 = cyclooxygenase-2, TCAs = tricyclic antidepressants.

Adapted from The American Geriatrics Society 2012 Beers Criteria Update Expert Panel: American Geriatrics Society updated Beers criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society 60: 616–631, 2012.

Drug-drug interactions

Because the elderly often take many drugs, they are particularly vulnerable to drug-drug interactions. The elderly also frequently use medicinal herbs and other dietary supplements (see Dietary Supplements) and may not tell their health care providers. Medicinal herbs can interact with prescribed drugs and lead to adverse effects. For example, ginkgo biloba extract taken with warfarin can increase risk of bleeding, and St. John's wort taken with an SSRI can increase risk of serotonin syndrome. Therefore, physicians should ask patients specifically about dietary supplements, including medicinal herbs and vitamin supplements.

Drug-drug interactions in the elderly differ little from those in the general population. However, induction of cytochrome P-450 (CYP450) drug metabolism (see Cytochrome P-450) by certain drugs (eg, phenytoin, carbamazepine, rifampin) may be decreased in the elderly; therefore, the change (increase) in drug metabolism may be less pronounced in the elderly. Many other drugs inhibit CYP450 metabolism and thus increase the risk of toxicity of drugs that depend on that pathway for elimination. Because the elderly typically use a larger number of drugs, they are at greater risk of multiple, difficult-to-predict CYP450 interactions. Also, concurrent use of 1 drug with similar adverse effects can increase risk or severity of adverse effects.

Inadequate monitoring

Monitoring drug use involves

  • Documenting the indication for a new drug

  • Keeping a current list of drugs used by the patient in medical records

  • Monitoring for achievement of therapeutic goals and other responses to new drugs

  • Monitoring necessary laboratory tests for efficacy or adverse effects

  • Periodically reviewing drugs for continued need

Such measures are especially important for elderly patients. Lack of close monitoring, especially after new drugs are prescribed, increases risk of adverse effects and ineffectiveness. Criteria to facilitate monitoring have been developed by the Health Care Financing Administration expert consensus panel as part of drug utilization review criteria. The criteria focus on inappropriate dosage or duration of therapy, duplication of therapy, and possible drug-drug interactions.

Inappropriate drug selection

A drug is inappropriate if its potential for harm is greater than its potential for benefit. Inappropriate use of a drug may involve

  • Choice of an unsuitable drug, dose, frequency of dosing, or duration of therapy

  • Duplication of therapy

  • Failure to consider drug interactions and correct indications for a drug

  • Appropriate drugs that are mistakenly continued once an acute condition resolves (as may happen when patients move from one health care setting to another)

Adverse effects of inappropriate drugs account for about 7% of emergency hospitalizations for patients 65 yr, and 67% of these hospitalizations are due to 4 drugs or drug classes—warfarin, insulin, oral antiplatelet drugs, and oral hypoglycemic drugs. Some classes of drugs are of special concern in the elderly (see Drug Categories of Concern in the Elderly). Some drugs are so problematic that they should be avoided altogether in the elderly, some should be avoided only in certain situations, and others can be used but with increased caution. The Beers Criteria (see Drug-Disease Interactions in the Elderly (Based on the American Geriatrics Society 2012 Beers Criteria Update)) lists potentially inappropriate drugs for the elderly by drug class; other similar lists are available. However, currently, there are no similar lists of drugs that should be used in the elderly; clinicians must weigh benefits and risks of therapy in each patient.

Despite the Beers and other criteria, inappropriate drugs are still being prescribed for the elderly; typically, about 20% of community-dwelling elderly received at least one inappropriate drug. In such patients, risk of adverse effects is increased. In nursing home patients, inappropriate use also increases risk of hospitalization and death. In one study of hospitalized patients, 27.5% received an inappropriate drug.

Some inappropriate drugs are available OTC; thus, clinicians should specifically question patients about use of OTC drugs and tell patients about the potential problems such drugs can cause.

The elderly are often given drugs (typically, analgesics, H 2 blockers, hypnotics, or laxatives) for minor symptoms (including adverse effects of other drugs) that may be better treated nonpharmacologically or by lowering the dose of the drug causing adverse effects. Initiating additional drugs is often inappropriate; benefit may be low, costs are increased, and the new drug may lead to additional toxicity.

Solving the problem of inappropriate use in the elderly requires more than avoiding a short list of drugs and noting drug categories of concern. A patient’s entire drug regimen should also be assessed regularly to determine potential benefit vs harm.

Lack of patient adherence

Drug effectiveness is often compromised by lack of patient adherence among the ambulatory elderly. Adherence is affected by many factors but not by age per se. Up to half of elderly patients do not take drugs as directed, usually taking less than prescribed (underadherence). Causes are similar to those for younger adults (see Adherence to a Drug Regimen). In addition, the following contribute:

  • Financial and physical constraints, which may make purchasing drugs difficult

  • Cognitive problems, which may make taking drugs as instructed difficult

  • Use of multiple drugs

  • Use of drugs that must be taken several times a day or in a specific manner

  • Lack of understanding about what a drug is intended to do (benefits) or how to recognize and manage adverse effects (harms)

A regimen using too frequent or too infrequent dosing, multiple drugs, or both may be too complicated for patients to follow. Clinicians should assess patients’ health literacy and abilities to adhere to a drug regimen (eg, dexterity, hand strength, cognition, vision) and try to accommodate their limitations—eg, by arranging for or recommending easy-access containers, drug labels and instructions in large type, containers equipped with reminder alarms, containers filled based on daily drug needs, reminder telephone calls, or medication assistance. Pharmacists and nurses can help by providing education and reviewing prescription instructions with elderly patients at each encounter. Pharmacists may be able to identify a problem by noting whether patients obtain refills on schedule or whether a prescription seems illogical or incorrect.


An excessive dose of an appropriate drug may be prescribed for elderly patients if the prescriber does not consider age-related changes that affect pharmacokinetics (see Pharmacokinetics) and pharmacodynamics (see Pharmacodynamics). For example, doses of renally cleared drugs should be adjusted in patients with renal impairment.

Generally, although dose requirements vary considerably from person to person, drugs should be started at the lowest dose in the elderly. Typically, starting doses of about one third to one half the usual adult dose are indicated when a drug has a narrow therapeutic index or when another condition may be exacerbated by a drug. The dose is then titrated upward as tolerated to the desired effect. When the dose is increased, patients should be evaluated for adverse effects, and drug levels should be monitored when possible.

Overdosage can also occur when drug interactions (see Drug-drug interactions) increase the amount of drug available or when different practitioners prescribe a drug and are unaware that another practitioner prescribed the same or a similar drug (therapeutic duplication).

Poor communication

Poor communication of medical information at transition points (from one health care setting to another) causes up to 50% of all drug errors and up to 20% of adverse drug effects in the hospital. When patients are discharged from the hospital, drug regimens that were started and needed only in the hospital (eg, sedative hypnotics, laxatives, proton pump inhibitors) may be unnecessarily continued by another prescriber, who is reluctant to communicate with the previous prescriber. Conversely, at admission to a health care facility, lack of communication may result in unintentional omission of a necessary maintenance drug.


Appropriate drugs may be underprescribed—ie, not used for maximum effectiveness. Underprescribing may increase morbidity and mortality and reduce quality of life. Clinicians should use adequate drug doses and, when indicated, multidrug regimens.

Drugs that are often underprescribed in the elderly include those used to treat depression, Alzheimer disease, pain (eg, opioids), heart failure, post-MI (β-blockers), atrial fibrillation (warfarin), hypertension, glaucoma, and incontinence. Also, immunizations are not always given as recommended.

  • Opioids: Clinicians are often reluctant to prescribe opioids for elderly patients with cancer or other types of chronic pain, typically because of concerns about adverse drug effects (eg, sedation, constipation, delirium) and development of dependence. When opioids are prescribed, the doses are often inadequate. Underprescribing opioids may mean that some elderly patients have needless pain and discomfort; elderly patients are more likely to report inadequate pain management than younger adults.

  • β-Blockers: In patients with a history of MI and/or heart failure, even in elderly patients at high risk of complications (eg, those with pulmonary disorders or diabetes), these drugs reduce mortality rates and hospitalizations.

  • Antihypertensives: Guidelines for treating hypertension in the elderly are available, and treatment appears to be beneficial (reducing risk of stroke and major cardiovascular events). Nonetheless, studies indicate that hypertension is often not controlled in elderly patients.

  • Drugs for Alzheimer disease: Acetylcholinesterase inhibitors and NMDA ( N -methyl- d -aspartate) antagonists have been shown to benefit patients with Alzheimer disease. The amount of benefit is unclear, but patients and family members should be given the opportunity to make an informed decision about their use.

  • Anticoagulants: Anticoagulants reduce risk of stroke in patients with atrial fibrillation. Although there is an increased risk of bleeding with anticoagulation, some older adults who might nonetheless benefit from anticoagulation are not receiving it.

  • Immunizations: Older adults are at greater risk of morbidity and mortality resulting from influenza, pneumococcal infection, and herpes zoster. Vaccination rates among older adults can still be improved.

In elderly patients with a chronic disorder, acute or unrelated disorders may be undertreated (eg, hypercholesterolemia may be untreated in patients with emphysema). Clinicians may withhold these treatments because they are concerned about increasing the risk of adverse effects or the time required to benefit from treatment. Clinicians may think that treatment of the primary problem is all patients can or want to handle or that patients cannot afford the additional drugs. Patients should participate in decision making about drug treatment so that clinicians can understand patients' priorities and concerns.


Before starting a new drug

To reduce the risk of adverse drug effects in the elderly, clinicians should do the following before starting a new drug:

  • Consider nondrug treatment

  • Discuss goals of care with the patient

  • Document the indication for each new drug (to avoid using unnecessary drugs)

  • Consider age-related changes in pharmacokinetics or pharmacodynamics and their effect on dosing requirements

  • Choose the safest possible alternative (eg, for noninflammatory arthritis, acetaminophen instead of an NSAID)

  • Check for potential drug-disease and drug-drug interactions

  • Start with a low dose

  • Use the fewest drugs necessary

  • Note coexisting disorders and their likelihood of contributing to adverse drug effects

  • Explain the uses and adverse effects of each drug

  • Provide clear instructions to patients about how to take their drugs (including generic and brand names, spelling of each drug name, indication for each drug, and explanation of formulations that contain more than one drug) and for how long the drug will likely be necessary

  • Anticipate confusion due to sound-alike drug names and pointing out any names that could be confused (eg, Glucophage ® and Glucovance ® )

After starting a drug

The following should be done after starting a drug:

  • Assume a new symptom may be drug-related until proved otherwise (to prevent a prescribing cascade).

  • Monitor patients for signs of adverse drug effects, including measuring drug levels and doing other laboratory tests as necessary.

  • Document the response to therapy and increase doses as necessary to achieve the desired effect.

  • Regularly reevaluate the need to continue drug therapy and stop drugs that are no longer necessary.


The following should be ongoing:

Medication reconciliation is a process that helps ensure transfer of information about drug regimens at any transition point in the health care system. The process includes identifying and listing all drugs patients are taking (name, dose, frequency, route) and comparing the resulting list with the physician’s orders at a transition point. Medication reconciliation should occur at each move (admission, transfer, and discharge).

Computerized physician ordering programs can alert clinicians to potential problems (eg, allergy, need for reduced dosage in patients with impaired renal function, drug-drug interactions). These programs can also cue clinicians to monitor certain patients closely for adverse drug effects.

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