Pharmacovigilance (PV)

Pharmacovigilance (PV) PV is concerned with detection, assessment & prevention of adverse reactions to drugs (ADRs) or any drug-related problems 2 2

Drug-Related Problems Lack of efficacy. Manufacturing defects. Medication errors. Drug misuse and abuse. Overdose. Contamination. Counterfeit products. 3

Recently, the concerns of PV have been widened to include: Herbal Traditional and complementary medicines Blood products Biologicals Medical devices Vaccines 4

Why Pharmacovigilance? The root of pharmacovigilance: Pharmaco (Greek)= Drug Vigilance (Latin)= to keep awake or alert Because information collected during pre-marketing phase are incomplete with regard to possible ADR Tests in animals are insufficiently predictive of human safety

Why Pharmacovigilance? In clinical trials: Patients are limited in number Conditions of use differ from those in clinical practice Duration of trials is limited 6

Why Pharmacovigilance? Information about rare adverse reactions, chronic toxicity, use in special groups (children, elderly or pregnant women) or drug interactions is often incomplete or not available Post-marketing surveillance by companies is therefore essential

Pre-marketing clinical trials do not have : Why Pharmacoviglance? Pre-marketing clinical trials do not have : Statistical power to detect rare ADRs To identify delayed ADRs To identify effects from long-term exposure PV plays a prominent role in establishing safety profile of marketed drugs 8 8

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Definition of ADR An ADR is defined according to definition of WHO “any response to a drug which is noxious, unintended & that occurs at doses used in man for prophylaxis, diagnosis, or therapy of diseases’’ 10

Epidemiology of ADRs ADRs represent a significant cause of morbidity & mortality Many ADRs are mild, sometimes serious & can cause death U.S, ADRs caused 100 000 deaths per year, 4th & 6th leading cause of death About 50% of ADRs are preventable 11 11

Importance of ADRs Prolong length of stay in hospitals Increase costs of patient care Commonest cause of drug withdrawal from market: Reductil (Sibutramine) 2010 Valdecoxib (Bextra) 2005 Rofecoxib (Vioxx) 2004 12

ADRs is considered serious if: Causes death of patient Life-threatening Prolong inpatient hospitalisation Causes significant or persist disability Congenital abnormality 13

Risk Factors predisposing to ADRs Age Long duration of treatment Polypharmacy Liver, kidney diseases

Causes of ADRs Patient Drug Prescriber Environmental factors

Causes of ADRs - Narrow therapeutic index, e.g. warfarin, digoxin 2. The drug - Narrow therapeutic index, e.g. warfarin, digoxin - Antimicrobials have a tendency to cause allergy - Ingredients of a formulation, e.g. colouring, flavouring 16 16

Drugs most commonly causing ADRs Anticancer drugs Immunomodulators Analgescis Warfarin Diuretics Digoxin Antibacterials Steroids Antihypertensives

Why report suspected ADRs? Documentation of ADRs in patients’ records is often poor Physicians fear that reporting of ADR may put them at risk Under-reporting is common phenomenon 18

Reporting Methods Spontaneous reporting: (Voluntary) Doctors, nurses & pharmacists are supplied with forms to record suspected ADRs Reporting ADRs to National Pharmacovigilance Centre In UK, this is called ‘Yellow Card system’

Prevention of ADRs Taking a drug history Reduce number of prescribed drugs Remembering that certain patients (elderly, those with liver or renal diseases) more susceptible to ADRs