S15) Pharmacovigilance Flashcards
What is pharmacovigilance?
- Pharmacovigilance is the process of identifying and then responding to safety issues about marketed drugs
- It involves surveying the safety of drugs and developing strategies to minimise the risk and optimise benefits
What are the aims of pharmacovigilance?
- Identify previously unrecognised drug safety hazards
- Elucidate factors predisposing to toxicity
- Obtain evidence of safety so that a new drug’s uses may be widened
- ‘False positive’ adverse drug reaction
What are the two types of ADRs?
- Type A
- Type B
What characterises Type A ADRs?
- Exaggerated pharmacological response
- Predictable
- Dose dependent
- Common
- High morbidity, low mortality
What characterises Type B ADRs?
- Not expected from known pharmacology
- Unpredictable
- Independent of dose
- Rare
- High mortality
What are the limitations of pre-marketing clinical studies in identifying drug safety issues?
- Small number of patients treated
- Frequent exclusion of patients who might be at greater risk of ADRs
- Limited duration of treatment
- Restricted doses
How can one identify ADRs?
- Spontaneous reporting
- Cohort studies
- Case control studies
Describe the three steps involved in the spontaneous reporting of ADRs
⇒ Recognition of a possible ADR
⇒ Establishing possible causal relationship
⇒ Reporting observations
What are the advantages of spontaneous reporting?
- Operates as soon as drug is marketed
- Involves all doctors
- Overlooks all drugs
- Inexpensive
- Continues indefinitely
What are the limitations of spontaneous reporting?
- Delays in reporting
- Poor quality data
- Misleading reports
- No control group
- Gross under-reporting of possible ADRs
Describe the two steps involved in cohort studies of ADRs
⇒ Identify group of patients exposed to drug
⇒ Observe to determine rate of occurrence of ADRs and outcomes
Describe the four steps involved in case-control studies of ADRs
⇒ Select cases with the adverse event/disease
⇒ Match controls without the adverse event/disease
⇒ Compare exposure to “risk factor” i.e. drug
⇒ Calculate odds ratio
What are the advantages of case-control studies?
- Good for rare ADRs
- Good when there is long latency
- Relatively low cost
- Indicate degree of increased risk
What are the limitations of case-control studies?
- Requires a prior hypothesis
- Suitable database not often available
- Many biases
- Expertise
- Credibility
What are the factors affecting the under-reporting of ADRs?
- Failure of patient to report ADR to their doctor
- ADR is too trivial
- Ignorance of reporting
- Lack of time
- Uncertainty of relationship of drug to presentation
- Relating to duration of marketed drug
- Experience and familiarity with the ADR
