What are adverse reactions in an aged person?

Adverse Drug Reactions in Older Adults

Older adults are at significantly higher risk for adverse drug reactions (ADRs) due to age-related physiological changes, polypharmacy, and multiple comorbidities, requiring careful medication management and increased monitoring to prevent harmful outcomes.

Definition and Classification of ADRs

• ADRs are defined as harmful or unpleasant reactions resulting from medication use that may require prevention, treatment, dosage adjustment, or medication discontinuation 1
• ADRs are commonly classified as Type A (dose-related, predictable) and Type B (non-dose-related, unpredictable) reactions 1
• More recent classification systems include the DoTS (Dose, Time, and Susceptibility) approach for better characterization of reactions 2

Prevalence and Impact in Older Adults

• Studies show that 15.3% of older adults taking prescribed medications experience adverse drug reactions 3
• ADRs are a leading cause of hospitalization in older adults, with recent data indicating they account for over 700,000 emergency department visits and 120,000 hospitalizations annually in the US 4
• Older adults (≥65 years) are twice as likely as younger individuals to visit emergency departments for ADRs and nearly seven times more likely to be hospitalized after such visits 4

Common High-Risk Medications in Older Adults

• Four medication classes are implicated in 67% of ADR-related hospitalizations in older adults: warfarin (33.3%), insulin (13.9%), oral antiplatelet agents (13.3%), and oral hypoglycemic agents (10.7%) 4
• NSAIDs carry significant risk in older adults, with a recent study implicating them in 23.5% of ADR-related hospitalizations 4
• Hypotensive drugs, antiparkinsonian medications, and psychotropics pose the greatest risk of adverse reactions, although diuretics cause the largest absolute number of ADRs due to their widespread use 3
• Opioids require special caution in older adults due to increased risk of respiratory depression, cognitive impairment, and falls 4

Age-Related Risk Factors

Physiological Changes

• Decreased renal function and medication clearance create a smaller therapeutic window between effective dosages and those causing adverse effects 4
• Changes in pharmacokinetics alter drug absorption, distribution, metabolism, and elimination 5
• Reduced end-diastolic volume, lower left ventricular ejection fraction, and decreased cardiac output affect medication response 4

Clinical Factors

• Multimorbidity increases complexity of medication regimens and risk of drug-disease interactions 4
• Polypharmacy (taking multiple medications) significantly increases ADR risk through drug-drug interactions 4, 5
• Cognitive impairment may increase risk of medication errors and make medication-related confusion more dangerous 4
• Frailty and decreased physiological reserve reduce the ability to tolerate medication side effects 2

Common Presentations of ADRs in Older Adults

• Older adults often present with atypical or nonspecific symptoms that may be mistakenly attributed to aging or existing conditions 5
• Common ADR manifestations include falls, orthostatic hypotension, delirium, renal failure, and gastrointestinal or intracranial bleeding 5
• Cardiovascular ADRs: angina, arrhythmias, hypertension, palpitations, tachycardia, and stress cardiomyopathy 6
• Neurological ADRs: dizziness, disorientation, excitability, headache, impaired memory, and psychomotor agitation 6
• Respiratory difficulties and gastrointestinal symptoms (nausea, vomiting) are also common 6

Strategies to Prevent ADRs in Older Adults

Medication Selection and Monitoring

• Start with the lowest effective dose in older adults, particularly those who are frail or have a history of sensitivity to medications 4
• Implement comprehensive medication reviews regularly to identify potentially inappropriate medications 4
• Reevaluate medication appropriateness at every healthcare transition (hospital admission, discharge, transfers between facilities) 4
• Use algorithmic tools and explicit prescribing criteria to identify medications associated with higher risk of adverse events 4

Prescribing Principles

• Prioritize treatments that optimize benefit, minimize harm, and enhance quality of life 4
• Consider the time horizon to benefit versus harm in relation to the patient's life expectancy 4
• Avoid prescribing cascades where medications are added to treat side effects of other medications 5
• Implement deprescribing when medications are no longer efficacious or when safer alternatives exist 5

Patient Education and Support

• Educate older adults about avoiding risky medication behaviors such as obtaining medications from multiple prescribers or saving unused medications 4
• Implement medication management interventions such as reminder systems and educational programs to improve adherence 4
• Assess medication management ability using validated tools like the Medication Management Ability Assessment (MMAA) or Drug Regimen Unassisted Grading Scale (DRUGS) 4

Special Considerations for Specific Conditions

• For older adults with cardiovascular disease, use caution with medications that may cause arrhythmias or exacerbate heart conditions 6
• In patients with renal or hepatic insufficiency, additional monitoring is needed due to decreased ability to process and excrete drugs 4
• For patients with mental health conditions, be vigilant for increased risk of ADRs due to potential drug interactions with psychotropic medications 4
• In patients with diabetes, monitor for medication-induced hypoglycemia, which now causes more hospitalizations than hyperglycemia among older Medicare beneficiaries 4

By understanding the unique risks and implementing appropriate prevention strategies, healthcare providers can significantly reduce the burden of adverse drug reactions in older adults and improve their overall health outcomes.