M06.01.13 Adverse Drug Reactions

Overview: Adverse drug reactions (ADRs) are harmful or unintended reactions to medications, occurring at doses normally used for treatment. ADRs can range from mild to severe and may manifest as adverse effects on specific organs or systems, allergic reactions, or drug-drug interactions. Understanding ADRs is essential for optimizing drug therapy and minimizing patient harm.

Key Concepts:

1. Types of Adverse Drug Reactions:
   • Type A (Augmented): Predictable reactions resulting from the pharmacological action of the drug at therapeutic doses. These reactions are dose-dependent and often related to the drug’s mechanism of action or pharmacokinetic properties.
   • Type B (Bizarre): Unpredictable reactions that are not related to the drug’s pharmacological action and may occur at any dose. Type B reactions include idiosyncratic reactions, hypersensitivity reactions, and drug allergies.
   • Type C (Chronic): Reactions resulting from prolonged use of a drug, such as cumulative toxicity or organ damage over time.
   • Type D (Delayed): Reactions that manifest after prolonged drug exposure, such as carcinogenic, teratogenic, or mutagenic effects.
   • Type E (End-of-Treatment): Reactions occurring upon discontinuation of drug therapy, such as withdrawal symptoms or rebound effects.
   • Type F (Failure): Reactions resulting from the failure of a drug to produce the desired therapeutic effect, such as drug resistance or treatment failure.
2. Risk Factors for ADRs:
   • Patient Factors: Age, sex, genetics, comorbidities, and concurrent medications can influence an individual’s susceptibility to ADRs.
   • Drug Factors: Drug properties (e.g., chemical structure, mechanism of action), dosage, route of administration, and duration of therapy can affect the likelihood and severity of ADRs.
   • Environmental Factors: Environmental factors such as diet, lifestyle, and exposure to toxins can modulate drug metabolism, absorption, or toxicity.
3. Monitoring and Reporting ADRs:
   • Healthcare professionals play a crucial role in monitoring patients for ADRs, recognizing their signs and symptoms, and reporting suspected ADRs to regulatory agencies or pharmacovigilance programs.
   • Pharmacovigilance aims to detect, assess, understand, and prevent ADRs through systematic monitoring of drug safety and surveillance of adverse event reports.

Bibliography:

1. Lazarou J, Pomeranz BH, Corey PN. Incidence of adverse drug reactions in hospitalized patients: a meta-analysis of prospective studies. JAMA. 1998; 279(15): 1200-1205. DOI: 10.1001/jama.279.15.1200.
2. Aronson JK. Adverse drug reactions. BMJ. 2006; 332(7542): 1115-1118. DOI: 10.1136/bmj.332.7542.1115.
3. Edwards IR, Aronson JK. Adverse drug reactions: definitions, diagnosis, and management. Lancet. 2000; 356(9237): 1255-1259. DOI: 10.1016/S0140-6736(00)02799-9.
4. World Health Organization. The importance of pharmacovigilance: safety monitoring of medicinal products. Geneva: World Health Organization; 2002. Available from: https://apps.who.int/iris/handle/10665/42493.

These references provide comprehensive insights into adverse drug reactions, including their classification, risk factors, monitoring strategies, and the importance of pharmacovigilance in ensuring drug safety.