Pharmacoepidemiology and pharmacovigilance post-marketing drug safety studies

Pharmacoepidemiology defined as "the study of the usage and effects of drugs in a large group of people" enables the cost-effective inclusion of significantly larger number of patients compared to pre-marketing studies, leading to a more accurate measurement of both the adverse and beneficial effects of drugs. Pharmacoepidemiological studies provide better quantification of the incidence of known adverse and beneficial effects in patients not enrolled in clinical trials, and those with multiple diseases and taking concurrent medication. These studies also assess the relative effectiveness and safety of drugs used for the same condition. Additionally, they provide information not obtainable from pre-marketing studies, such as insight into rare and delayed effects, pattern of drug utilization, effects of overdose, economic implications of drug use, and reassurance regarding drug safety (Strom, 2019;Crescioli et al., 2022). Whereas, pharmacovigilance defined as "the science and practices relating to the identification, assessment, understanding, and prevention of adverse drug events or any other potential drug-related problems" (WHO, 2002). It plays an important role in post-marketing drug safety studies. It encompasses detecting, assessing and reporting adverse drug reactions (ADRs), signal detection, elucidation of pharmacological and toxicological properties of drugs, identifying high risk patients, drug interactions, ADRs risk management, post-marketing surveillance, and taking regulatory actions when safety concerns arise (Raj et al., 2019;Trifirò and Crisafulli, 2022).The full implementation of pharmacovigilance practices is one of the prerequisites for the rational use of drugs. Pharmacoepidemiology provides vital methodological support in achieving and maintaining this pharmacovigilance contribution in the periods before, during and after the use of drugs (Akici and Oktay, 2007;Gulmez et al, 2020). Pharmacoepidemiology and pharmacovigilance work in synergy (Bérard, 2021;Lavertu et al., 2021;Crescioli et al., 2022).These studies are crucial for augmenting pre-marketing evidence, providing insights into the riskbenefit profile of drugs as well as its use in larger patient populations. They hold significant potential to contribute to post-marketing drug safety assessments. Utilizing real-world data sources, including spontaneous reporting system databases like the World Health Organization (WHO) global pharmacovigilance database (VigiBase), the FDA Adverse Event Reporting System (FAERS), the EudraVigilance database of European Medication Agency, as well as claims databases, electronic healthcare records, and drug/disease registers, pharmacovigilance and pharmacoepidemiologic studies continuously monitor approved and marketed drugs. This ongoing monitoring process is crucial for the timely detection of new ADRs (Bérard, 2021;Crisafulli et al., 2023). In conclusion, articles included in this special issue highlight the importance pharmacoepidemiology and pharmacovigilance studies in enhancing our understanding of drug utilization and safety issues in patients suffering from different diseases. It also advocates that real world data sources are instrumental in timely detection of ADRs and continued surveillance of marketed drugs throughout the duration of their use to ensure that their benefit to risk ratio are and remain in acceptable limits.