JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Pharmacy IV PHARMACOVIGILANCE Previous Question Paper (February-2022 - R17)

The WHO Drug Monitoring Programme, established in 1968, serves as the global framework for the collection, assessment, and communication of information regarding adverse drug reactions (ADRs). It operates through the WHO Programme for International Drug Monitoring (PIDM), which coordinates a network of national pharmacovigilance centers worldwide.

The programme functions through several key components:

1. National Centres: Individual countries establish national pharmacovigilance centers that collect spontaneous reports of suspected ADRs from healthcare professionals and the public.
2. VigiFlow: This is the web-based software provided by the WHO to national centers for the systematic management and processing of individual case safety reports (ICSRs).
3. VigiBase: The core of the programme is VigiBase, the WHO global database of ICSRs. It is maintained by the Uppsala Monitoring Centre (UMC) in Sweden, which acts as the WHO collaborating center for international drug monitoring.
4. Data Analysis: The UMC utilizes advanced statistical tools, such as the Information Component (IC), to perform signal detection within VigiBase. This helps identify potential safety issues or previously unrecognized drug-event associations.
5. Signal Communication: When a potential safety signal is identified, the UMC and WHO evaluate the evidence. If confirmed, the information is disseminated to member countries through newsletters, safety alerts, and the WHO Pharmaceuticals Newsletter, enabling regulatory bodies to take appropriate action, such as updating product labels or restricting drug use.

The primary objective of the programme is to enhance patient safety by ensuring that the benefits of medicines outweigh their risks. By pooling data from diverse populations globally, the programme allows for the detection of rare ADRs that might not be apparent in smaller, regional databases or individual clinical trials. It also promotes the development of pharmacovigilance capacity in developing nations, fostering a global culture of drug safety and rational medicine use.

Causality assessment is the systematic evaluation of the likelihood that a specific medicinal product is the cause of an observed adverse event. It is a critical process in pharmacovigilance used to determine the strength of the relationship between drug exposure and the clinical outcome, facilitating regulatory decisions and safety signaling.

The primary methods for causality assessment include:

• Expert Judgment (Clinical Case Review): The most traditional method, where experienced clinicians review individual case reports. They evaluate the temporal relationship, dechallenge (improvement after stopping the drug), rechallenge (recurrence upon re-exposure), and alternative explanations (e.g., disease progression or other medications). While highly nuanced, it is subjective and prone to inter-rater variability.
• Algorithmic Methods: These use structured questionnaires or decision trees to standardize the assessment process. The Naranjo Probability Scale is the most widely used, assigning scores to specific criteria to categorize the relationship as definite, probable, possible, or doubtful. Other examples include the Karch and Lasagna method and the Jones algorithm. These improve consistency but may oversimplify complex clinical scenarios.
• Probabilistic (Bayesian) Methods: These utilize statistical models to calculate the probability of causality based on prior knowledge and observed data. The BGA (Bayesian Pharmacovigilance Analysis) approach, such as the BCPNN (Bayesian Confidence Propagation Neural Network), is used by organizations like the WHO to detect signals in large databases by comparing observed reporting rates against expected background rates.
• WHO-UMC System: A standardized, globally recognized method that categorizes causality into six classes: certain, probable/likely, possible, unlikely, conditional/unclassified, and unassessable/unclassifiable. It combines clinical judgment with standardized criteria to ensure international consistency in safety reporting.

Effective causality assessment requires a multidisciplinary approach, balancing the structured rigor of algorithms with the clinical insight of medical experts to ensure patient safety and accurate risk-benefit profiling.