Once a drug is approved and enters the market, the responsibility of monitoring its safety does not end. In fact, this is the stage where real-world evidence becomes crucial. Post Marketing Surveillance (PMS) refers to all activities that monitor the safety, effectiveness, and adverse effects of a drug after it has been released for public use. This stage is also called Phase IV in the drug development process.
Post marketing surveillance helps identify rare, long-term, or population-specific side effects that may not appear during pre-approval clinical trials. This guide breaks down the essential methods of post marketing surveillance used globally.
Why Is Post Marketing Surveillance Important?
PMS is vital because pre-approval clinical trials involve controlled settings and limited participant numbers. Real-world usage, however, includes diverse populations such as:
- Pregnant women
- Children and elderly individuals
- Patients with comorbidities
- People using multiple medications
Therefore, PMS helps detect:
- Rare or delayed adverse drug reactions (ADRs)
- Drug-drug or drug-food interactions
- Lack of effectiveness in real-life settings
- Misuse, overdose, or medication errors
- Quality issues such as contamination or manufacturing changes
1. Spontaneous Reporting Systems (SRS)
This is the most widely used method of post marketing surveillance. In this system, healthcare professionals, pharmacists, and sometimes patients report suspected adverse drug reactions to national or regional pharmacovigilance authorities.
Key characteristics:
- Voluntary reporting
- Quick and cost-effective
- Useful for identifying rare and unexpected ADRs
Examples include:
- India: Pharmacovigilance Programme of India (PvPI)
- USA: FDA Adverse Event Reporting System (FAERS)
- Europe: EudraVigilance
Limitations: Under-reporting is common, and reports are often incomplete or unverified.
2. Case Reports and Case Series
Case reports involve detailed documentation of a single patient’s adverse reaction, while case series include multiple patient reports. These reports help identify unusual or new ADRs that may trigger further investigation.
They are especially useful for detecting very rare but serious reactions.
3. Cohort Studies
Cohort studies follow a group of drug users and compare them with a non-exposed group. They may be prospective or retrospective.
Advantages:
- Provide high-quality evidence
- Good for calculating incidence of ADRs
- Useful for long-term safety evaluation
Limitations: Time-consuming and expensive.
4. Case-Control Studies
In case-control studies, individuals with a specific adverse event (cases) are compared to individuals without the event (controls). Researchers look backward to assess the drug exposure history of both groups.
This method is ideal when the adverse event is rare.
Advantages:
- Cost-effective
- Quick to conduct
Limitations: Cannot calculate incidence; may involve recall bias.
5. Prescription Event Monitoring (PEM)
PEM is a form of active surveillance where data is collected from physicians when they prescribe a newly marketed drug. Each prescription acts as an “entry” into the monitoring system.
Characteristics include:
- Large-scale monitoring
- Captures real-world prescribing patterns
- Provides insight into both safety and effectiveness
6. Registries
Registries are organized systems that collect data on specific drugs, diseases, or populations. Examples include pregnancy registries, cancer registries, and vaccine registries.
Benefits of registries:
- Long-term follow-up
- Large and diverse patient populations
- Helps evaluate drug use in special populations like pregnant women
7. Active Surveillance Programs
Unlike spontaneous reporting, active surveillance actively tracks and collects ADR data through structured programs. This may include:
- Telephone interviews
- Electronic health record monitoring
- Targeted safety studies
It provides more reliable data but requires significant resources.
8. Phase IV Clinical Trials
These post-marketing trials evaluate:
- Long-term effectiveness
- Impact on quality of life
- Rare side effects
- Real-world benefits vs. risks
Regulatory agencies may require Phase IV trials as a condition for drug approval, especially if earlier data was limited.
9. Drug Utilization Studies
These studies analyze how drugs are prescribed and used in real-life scenarios. They help identify misuse, overuse, underuse, and irrational prescribing patterns.
10. Intensive Monitoring and Hospital-Based Studies
Certain hospitals participate in ongoing pharmacovigilance activities involving real-time monitoring of ADRs. These centers generate detailed safety profiles of commonly used medications.
Detailed Notes:
For PDF style full-color notes, open the complete study material below:
PATH: PHARMD/ PHARMD NOTES/ PHARMD FIFTH YEAR NOTES/ CLINICAL RESEARCH/ METHODS OF POST MARKETING SURVEILLANCE.