4. ADVERSE DRUG REACTION MANAGEMENT

Adverse Drug Reaction (ADR) management is a critical component of clinical pharmacy practice. ADRs are unwanted, harmful, or unexpected responses to medications that occur at normal doses. Effective identification, assessment, reporting, and prevention of ADRs help improve patient safety, reduce hospital stay duration, and enhance the quality of healthcare. Clinical pharmacists play a vital role in detecting ADRs early and ensuring appropriate corrective actions.

Definition of Adverse Drug Reaction

An Adverse Drug Reaction (ADR) is defined as any harmful or unintended response to a drug occurring at normal doses used in humans for diagnosis, treatment, or prevention of disease. ADRs may result from drug interactions, allergic reactions, or individual patient characteristics such as age, genetics, or co-existing illnesses.

Types and Classification of ADRs

ADRs are classified based on mechanism, severity, and predictability.

1. According to Mechanism (ABCDEF Classification)

  • Type A (Augmented): Predictable, dose-related (e.g., hypoglycemia from insulin).
  • Type B (Bizarre): Unpredictable, not dose-related (e.g., anaphylaxis to penicillin).
  • Type C (Chronic): Long-term therapy related (e.g., adrenal suppression from steroids).
  • Type D (Delayed): Occurs after prolonged use or years later (e.g., carcinogenicity).
  • Type E (End-of-use): Withdrawal reactions (e.g., opioid withdrawal).
  • Type F (Failure): Unexpected failure of therapy (e.g., antibiotic resistance).

2. According to Severity

  • Mild: Requires minimal intervention, usually self-limiting.
  • Moderate: Requires change in therapy or extended hospitalization.
  • Severe: Life-threatening, causing permanent damage or requiring intensive care.

3. According to Frequency

  • Very common
  • Common
  • Uncommon
  • Rare
  • Very rare

Risk Factors for ADRs

  • Polypharmacy and drug interactions
  • Extremes of age (neonates and elderly)
  • Renal or hepatic impairment
  • Genetic factors affecting drug metabolism
  • History of allergies or previous ADRs
  • Chronic diseases such as diabetes or heart failure

Detection of ADRs

Early detection is essential to prevent complications. Clinical pharmacists identify ADRs by:

  • Reviewing patient medication profiles
  • Monitoring laboratory tests (e.g., LFTs, RFTs, electrolytes)
  • Observing clinical symptoms
  • Evaluating patient complaints (e.g., rash, nausea, dizziness)
  • Identifying drug-drug interactions

Assessment and Evaluation of ADRs

Once an ADR is suspected, clinical pharmacists use various tools to assess causality, severity, and preventability.

1. Causality Assessment Tools

  • Naranjo Algorithm
  • WHO-UMC Scale
  • Hartwig Severity Scale
  • Schumock and Thornton Preventability Criteria

Management of ADRs

ADR management aims to minimize harm and prevent recurrence.

1. General Management Strategies

  • Stop or replace the suspected drug.
  • Treat symptoms (e.g., antihistamines for allergic reactions).
  • Adjust dosage or frequency.
  • Provide supportive therapy.

2. Specific Management Scenarios

  • Allergic reactions: Administer epinephrine, corticosteroids, or antihistamines.
  • Drug toxicity: Use antidotes (e.g., N-acetylcysteine for paracetamol toxicity).
  • Severe ADRs: Transfer to ICU and discontinue all non-essential medications.

Documentation of ADRs

Accurate documentation helps improve pharmacovigilance and patient safety. Record details such as:

  • Suspected drug and dose
  • Description of the reaction
  • Onset and duration
  • Lab findings
  • Actions taken and outcomes

ADR Reporting Systems

Reporting ADRs supports national pharmacovigilance programs. Common reporting systems include:

  • WHO Uppsala Monitoring Centre (UMC)
  • National Pharmacovigilance Program of India (PvPI)
  • Hospital ADR Monitoring Committees

Role of Clinical Pharmacists in ADR Management

  • Identify and evaluate ADRs during daily clinical rounds.
  • Educate healthcare professionals and patients.
  • Prevent drug interactions and inappropriate prescribing.
  • Promote safe medication practices.
  • Report ADRs to pharmacovigilance centers.
  • Maintain ADR databases and participate in audits.
  • Develop hospital guidelines for high-risk medications.

Strategies to Prevent ADRs

  • Promote rational prescribing.
  • Use clinical decision support systems.
  • Monitor high-risk drugs closely.
  • Educate patients about proper medication use.
  • Avoid polypharmacy whenever possible.
  • Regular medication reconciliation.

Detailed Notes:

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