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).
Reasons for Drug-Related Problems:
Elderly people often take many drugs and have age-related changes in pharmacodynamics and pharmacokinetics; both increase the risk of adverse effects.
Adverse drug effects may occur when drugs are prescribed and taken appropriately; eg: new-onset allergic reactions are not predictable or preventable. Certain drug classes commonly involved are antipsychotics, warfarin, antiplatelet agents, hypoglycemic drugs, antidepressants, and sedative-hypnotics.
Drug-disease interactions: Drug-disease interactions are of special concern in the elderly. Distinguishing often subtle adverse drug effects from the effects of disease is difficult and may lead to a prescribing cascade, which 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.
Many drugs have adverse effects that resemble symptoms of disorders common among the elderly. 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, this can go as far as some people having to use external catheters for men or pads for women.. 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.
Drug-drug interactions: Elderly often take many drugs, they are particularly vulnerable to drug-drug interactions. The elderly also frequently use medicinal herbs and other dietary supplements. Medicinal herbs can interact with drugs and lead to adverse effects. For example, ginkgo biloba extract taken with warfarincan increase risk of bleeding,
Inappropriate drug selection: 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
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.
Prevention
To reduce the risk of adverse drug effects in the elderly, clinicians should do the following before starting a new drug:
- Consider nondrug treatment
- 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)
- 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®)
Medication reconciliation is a process of 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.