Adverse Drug Reactions in Special Populations

Introduction to Adverse Drug Reactions

Adverse drug reactions are defined as responses to a medicinal product that are noxious and unintended, occurring at doses normally used in humans for prophylaxis, diagnosis, or therapy of disease, as supported by the World Health Organization (WHO), the Food and Drug Administration (FDA), and the European Medicines Agency (EMA) 1
Adverse events are defined as medical events that involve hospitalization, death, life-threatening illness, disability, or other medically important conditions, according to the Centers for Disease Control and Prevention (CDC) 2, 3

Women have approximately 1.5 times higher risk of developing Adverse Drug Reactions (ADRs) than men, according to the American College of Cardiology 4
Polypharmacy significantly increases ADR risk, especially in older adults, as reported by the European Society of Cardiology 5
Genetic factors can predispose individuals to specific ADRs, highlighting the importance of pharmacogenetic testing in high-risk scenarios 4

Adverse drug reactions can be classified into several types, including Type A (Augmented), Type B (Bizarre), Type C (Chronic), Type D (Delayed), Type E (End of use), Type F (Failure), and Type G (Genetic) 1

For vaccines, adverse events should be reported to the Vaccine Adverse Events Reporting System (VAERS), which can be accessed online or by phone, as recommended by the CDC 3
For medications (including antiretrovirals) and biologics, adverse events should be reported to FDA's MedWatch program, which can be accessed online, by mail, or by phone, according to the FDA 2
Events listed by manufacturers as contraindications to subsequent doses of the medication should be reported, as recommended by the CDC 3
Unusual or severe toxicities believed to be associated with medication use should be reported, according to the CDC 2
Any clinically significant adverse events that occur after administration of medications, even if causal relation is uncertain, should be reported, as recommended by the CDC 3
Missing drug interactions that contribute to adverse reactions should be reported, as recommended by the CDC 2

Reactions to medications can range from mild infusion reactions to severe life-threatening anaphylaxis, and monitoring for neuropsychiatric events is recommended, particularly in adolescents and children, as reported by the National Comprehensive Cancer Network (NCCN) 6, 7
Management of adverse drug reactions may include decreasing the infusion rate or temporarily stopping the infusion, and antihistamines may provide symptomatic relief in some cases 6, 8
Proper documentation of adverse drug reactions should include reaction details, timing, and management to assess true risk for future medication use 1, 9
Even mild reactions like skin flushing should be documented as they may predict more severe reactions with continued exposure, and patients who have had mild reactions to certain medications may develop more serious reactions even when the drug is slowly infused in subsequent administrations 6