Why older adults are more vulnerable to adverse drug reactions
As the body ages, several physiological changes can affect how drugs are absorbed, distributed, metabolized, and eliminated. This natural process, known as altered pharmacokinetics, significantly increases the risk of adverse drug reactions (ADRs) in older adults. Additionally, older adults often manage multiple chronic health conditions, a state known as multimorbidity, which necessitates taking multiple medications. This practice, called polypharmacy, is a major risk factor for harmful drug-drug interactions and side effects. Changes in the body's responsiveness to medications (pharmacodynamics), such as increased sensitivity to certain drug classes, further complicate medication management.
The most frequently observed adverse drug reactions
Central Nervous System Effects
- Falls and Fractures: Medication-induced dizziness, sedation, and impaired balance are a leading cause of falls in the elderly. Benzodiazepines, antidepressants, and antipsychotics are frequently implicated.
- Delirium and Cognitive Impairment: Confusion, memory problems, and hallucinations can result from anticholinergic drugs, opioids, and sedatives. This may be mistakenly attributed to dementia rather than medication side effects.
Cardiovascular and Bleeding Events
- Bleeding: Medications like anticoagulants (e.g., warfarin) and antiplatelets (e.g., aspirin) increase the risk of serious gastrointestinal or intracranial bleeding.
- Orthostatic Hypotension: A sudden drop in blood pressure when standing can cause dizziness, lightheadedness, and falls. This is a common side effect of antihypertensive medications and diuretics.
- Heart Failure Exacerbation: NSAIDs can cause fluid retention, worsening heart failure symptoms.
Gastrointestinal Issues
- Gastrointestinal Bleeding: Long-term use of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) significantly increases the risk of peptic ulcers and internal bleeding.
- Constipation and Diarrhea: Common side effects caused by opioids and drugs with anticholinergic properties.
- Clostridioides difficile Infection: Prolonged use of proton pump inhibitors (PPIs) and certain antibiotics can increase susceptibility to this severe intestinal infection.
Renal and Metabolic Problems
- Acute Kidney Injury: NSAIDs can impair kidney function, particularly in individuals with pre-existing renal issues or heart failure.
- Electrolyte Imbalances: Diuretics can lead to abnormal electrolyte levels, such as hypokalemia (low potassium) or hyponatremia (low sodium).
- Hypoglycemia: Certain diabetes medications, like sulfonylureas, can cause dangerously low blood sugar levels in older adults.
Comparison of common geriatric ADRs and implicated drug classes
| Adverse Reaction | Common Drug Classes Implicated | Typical Signs and Symptoms |
|---|---|---|
| Falls | Benzodiazepines, Antidepressants, Antipsychotics, Diuretics, Antihypertensives | Dizziness, loss of balance, sedation, unsteadiness |
| Delirium/Confusion | Anticholinergics, Opioids, Sedatives, Antipsychotics | Hallucinations, disorientation, memory problems, altered awareness |
| Bleeding | Anticoagulants (Warfarin, NOACs), Antiplatelets (Aspirin), NSAIDs | Easy bruising, blood in urine/stool, bleeding gums, nosebleeds |
| Orthostatic Hypotension | Antihypertensives, Diuretics, Antidepressants, Antipsychotics | Dizziness or fainting upon standing, lightheadedness |
| Renal Dysfunction | NSAIDs, Diuretics | Fluid retention, fatigue, changes in urination |
| Gastrointestinal Issues | NSAIDs, Opioids, Anticholinergics, PPIs | Constipation, diarrhea, nausea, acid reflux, stomach bleeding |
Strategies for preventing and managing ADRs in older adults
- Regular Medication Review: Schedule frequent, detailed reviews with a healthcare team, including a doctor and a pharmacist, to assess the continued necessity and appropriateness of all medications.
- Deprescribing: Proactively reduce or stop medications that are no longer beneficial or may cause harm, focusing on patient goals and quality of life.
- Start Low and Go Slow: When starting a new medication, clinicians should begin with the lowest possible dose and increase it gradually while monitoring for adverse effects.
- Use Validated Tools: Healthcare providers can utilize tools like the Beers Criteria to identify potentially inappropriate medications for older adults.
- Patient and Caregiver Education: Empower older adults and their caregivers to recognize potential side effects and understand the purpose of each medication.
- Medication Reconciliation: Ensure accurate and complete medication lists during transitions of care (hospital to home) to prevent errors and polypharmacy.
- Consider Non-pharmacologic Alternatives: Explore alternative therapies, such as exercise for pain or cognitive behavioral therapy for anxiety, to reduce reliance on certain drugs.
For more guidance, consult the American Geriatrics Society's resources on medication safety in older adults.
Conclusion
Adverse drug reactions are a significant and often preventable health risk for the elderly, driven by factors like polypharmacy and age-related physiological changes. Recognizing common ADRs—such as falls, delirium, bleeding, and GI problems—is the first step toward safeguarding an older adult's health. By implementing proactive strategies like regular medication reviews, deprescribing unnecessary medications, and educating patients and caregivers, healthcare providers can minimize risks and enhance the well-being of older adults.
