Monitoring System To Detect Drug Reactions And Drug Interactions: To obtain information on serious, rare, and unknown ADRs at an early stage i.e. “Early Warning”, ADRs have been monitored in many countries since the beginning of 1960.
Intermittent assessment of ADRs which are reported in a hospital helps in differentiating the pattern of ADRs and thereby assist in designing steps to improve the safety of drug use in the hospital. These ADRs data contribute to the national and international database of ADRs which may further contribute to decision making on drug safety as well as to contribute to design strategy for patient education. Following are steps used in monitoring the adverse drug reaction:
I. Identifying Adverse Drug Reactions
Generally, the ADRs are monitored in the pre-marketing and post-marketing surveillance studies. There are some disadvantages of pre-marketing studies in that they are deficient in generating sufficient knowledge. The data are generated from animal studies and a few numbers of human volunteers and are directly extrapolated these data into human risk. In a premarketing study, the clinical trial cannot be done on a rare group like; children, the elderly, and pregnant women. The data generated in a pre-marketing study cannot give the information for long-term adverse effects.
In post-marketing surveillance ADRs can be monitored by different methods they are as follows:
1. Unreliable Reporting: Mostly, the very first ADR come through unreliable report from the individual doctor when the patient has noticed peculiar effects. Such type of unreliable effect needs to be verified by further studies. Sometimes these effects fail to confirm in further studies.
2. Intensive Monitoring Studies: These studies provide well organized and thorough compilation of data from well-defined groups of patients. The observation was done by particularly trained healthcare experts who dedicate their service toward the recording of all the drugs administered and all the events observed.
3. Spontaneous Reporting System: For monitoring the safety of marketed product spontaneous reporting system is the primary method of monitoring. In this system, the healthcare professional is encouraged to report any or all kinds of reactions that he considers due to the use of medicine. Typically, awareness is focused on new drugs and serious ADRs observed.
4. Cohort Studies (Prospective Studies): In these studies, recognize the patients during drug administration and record any event observed. The major weakness of this method is very small numbers of patients are involved as well as the lack of a suitable control group to distinguish the incidence of any adverse events. Results of such kind of study are difficult to interpret and justify for the newly marketed product.
5. Case-Control Studies (Retrospective Studies): In these studies, patient those shows adverse events are screened to see the events due to the drug was taken or not. The commonness of drugs taken by a group of patients compared with reference population who do not have symptoms. Thus, case-control studies consider suitable for the determination of ADRs while it is not suitable for monitoring ADRs of a completely new drug.
6. Case Cohort Studies: In these studies, a patient who shows ADRs due to drug administration are screened and compared for similarity of symptoms who received similar drugs in prospective cohort studies.
7. Record Linkage: In this system, all patient’s data related to general practice records of illness and prescription records are linked together. Thus, it is easy to match the ADRs of prescribed drugs. It is also called a prescription event monitoring system. In this system, all prescription issued by a specific physician for a particular drug is obtained. Thus, it is easy for the physician to scrutinize similar ADRs which are reported by the patient after taking similar medicine. This scheme is less expensive and time-consuming than other monitoring methods.
8. Meta-Analysis: Meta-analysis needs to perform when there is variation in study results. In this study, a quantitative investigation of two or more independent studies needs to be performed to identify ADRs and assess drug safety.
II. Assessing Cause between Drug and Suspected Reaction
In this method, a relationship between the drug and suspected drug events is established. There are three methods for the assessment of cause:
- View of an individual specialist
- View of expert’s panel
- Official algorithms.
There is no standard method for the assessment of the cause of ADRs for a particular drug. There are categorizations of causes for the ADRs which are based on the scale used. As per the World Health Organization (WHO) the categorization like definite/certain, probable, possible, unclassifiable, unlikely.
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