The Good Clinical Practice (GCP) guidelines of the International Council for Harmonization (ICH) define an adverse event (AE) as any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. In accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) E2A guideline, a serious adverse event or reaction is any untoward medical occurrence that at any dose results in death is life threatening, requires inpatient hospitalisation or results in prolongation of existing hospitalisation, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, is a medically important event or reaction.

Medical and scientific judgment should be exercised in deciding whether other situations should be considered serious such as important medical events that might not be immediately life threatening or result in death or hospitalisation but might jeopardise the patient or might require intervention to prevent one of the other outcomes listed in the definition above. Examples of such events are intensive treatment in an emergency room or at home for allergic bronchospasm, blood dyscrasias or convulsions that do not result in hospitalization, or development of drug dependency or drug abuse.

Cases of adverse drug event that are both serious and unexpected are subject to expedited reporting. The reporting of serious expected reactions in an expedited manner varies among countries. Non-serious adverse reactions, whether expected or not, would normally not be subject to expedited reporting. For either reports from studies and other solicited sources, all cases judged by the reporting healthcare professional or the marketing Authorization Holder (MAH) as having a possible causal relationship to the medicinal product would qualify as ADRs. For purposes of reporting, spontaneous reports associated with approved drugs imply a suspected causal relationship.

Pharmacovigilance is the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other medicine/vaccine related problem. All medicines and vaccines undergo rigorous testing for safety and efficacy through clinical trials before they are authorized for use. Signal detection and its assessment is the most important aspect in pharmacovigilance, which plays a key role in ensuring that patients receive safe drugs. For detection of adverse drug reactions, clinical trials usually provide limited information as they are conducted under strictly controlled conditions.

Sources of clinical safety data during the post-approval phase described in the ICH E2D Guideline are Spontaneous reports; Literature; Internet; Other sources (lay press or other media). Organised data collection systems (these include clinical trials, registries, post-approval named patient use programs, other patient support and disease management programs, surveys of patients or health care professionals, information gathering on efficacy or patient outcome; some of these may involve record-linkage, i.e. finding entries that refer to the same entity in two or more files). Individual Case Safety Reports (ICSR), such as Suspected Unexpected Serious Adverse Reactions (SUSARs) that originate from regulatory authorities. Inter-company exchange of safety information.

The process for signal management consist of following steps: Signal detection, Validation and Confirmation, Analysis, Prioritization, Assessment, Recommendation(s) for action and exchange of information. The assessment of signals is done in terms of various factors. First, the data in the report(s) need to be of good quality when a signal of a new adverse drug reaction is considered. There should be sufficient data to fully assess the relationship of the drug to the event.

Active post marketing surveillance is necessary to receive information about the safety of the drugs at an early stage. When developing new methods for active post-marketing surveillance, one has to bear in mind the important of to gather information in a timely manner.