Biosimilars, like all biological drugs, undergo special vigilance for a 5-year period after they are approved. Drugs subject to this vigilance period are marked with a black triangle. In cooperation with the World Health Organization (WHO), the countries of the European Union have developed pharmacovigilance programmes for all biosimilars placed on the market so that health professionals may report any adverse event or change in efficacy not identified during the approval period. That does not mean that the clinical studies that led to approval of the drug were incomplete. Rather, it means that those studies are conducted under controlled conditions which sometimes do not correspond to the complex situations that may arise in the real world.
These pharmacovigilance programmes consist of a number of organised scientific activities with collection of data related to detection, evaluation, comprehension, prevention and reporting of potential safety problems with pharmaceutical products. They aim to promote identification and evaluation of signs of risk so that these signs may be handled appropriately. Adverse events for biosimilars may be monitored more precisely using all evidence previously obtained with the reference drug.
The ever-increasing use of biosimilars has required market authorisation-holding companies, regulatory agencies and other entities to create a data collection system to examine the large volume of pharmacovigilance data and determine the safety of these medicines. This has been the case of the biosimilar filgrastim. This drug has been marketed in the European Union since 2009, and approximately 7 million days of patient exposure have been amassed. Thus, a huge amount of post-marketing experience has been accumulated, which means that the drug’s safety profile is known in great detail. Information has been collected throughout all these years and, based on pharmacovigilance data, it has been possible to conclude that the safety profile and immunogenicity of this biosimilar and its original are similar, and that the risk–benefit ratio is highly favorable(1, 2).
However, for these pharmacovigilance programmes to be effective, local and global requirements for traceability and interchangeability, which are required to properly and safely place the product on the market, should be taken into account. That is to say, in order to identify the drug causing a potential adverse event, it is important to know what products and batches the patient has received in order to be able to perform a detailed analysis.
- US Food and Drug Administration. FDA Oncologic Drugs Advisory Committee Meeting: Zarxio (filgrastim). January 7, 2015. Disponible en: http://www.fda.gov/downloads/Advisory-Committees/CommitteesMeetingMaterials /Drugs/OncologicDrugsAdvisoryCommittee/UCM428782.pdf. Con acceso el 3 de Enero de 2016
- Gascón P, Tesch H, Verpoort K, et al. Clinical experience with Zarzio in Europe: What have we learned? Support Care Cancer. 2013;21:2925-32