Biosimilars are products designed to act in a similar way to the originator or reference product that has been previously approved for a particular disease. However, biosimilars are not the same as generics, which have simpler chemical structures and are considered to be identical to their reference medicines. Biosimilars are produced by recombinant DNA technology in living organisms as opposed to the chemical synthesis required for generics [2].

Consider ibuprofen: a small molecule chemical drug with a mass of 206 g/moL. In contrast, the biological infliximab has a molecular mass of 144,190 g/moL. Small molecule chemical drugs have little ability to initiate an immune response and remain relatively stable over time. In contrast, biologicals degrade over time and have the ability to generate a significant immune response. Thus, the production of a biological is an inherently unstable situation requiring special handling and storage, as even subtle changes in alterations in manufacturing, storage and transport can change the properties of the drug.

Acknowledging these differences, the European Medicines Agency (EMA) in its guidance document – Questions and answers on biosimilar medicines [3] – defines a biosimilar as follows:

‘A biosimilar medicine is a biological medicine that is developed to be similar to an existing biological medicine (the ‘reference medicine’). Biosimilars are not the same as generics, which have simpler chemical structures and are considered to be identical to their reference medicines.’

In light of the complexity of biologicals and acknowledging the fact that biosimilars are not identical but a close approximation of the originator drug, a different, more stringent, set of regulatory rules are required for their approval [4]. In addition to the requirement to demonstrate pharmacokinetic equivalence (which is where regulation stops for small molecule chemical entities), biosimilars must also provide data supporting comparable efficacy and safety.

Conflict of interest
The authors of the research paper [1] declared that there were no conflicts of interest.

Editor’s comment
Readers interested to learn more about biosimilars are invited to visit www.gabi-journal.net to view the following manuscript published in GaBI Journal:

Biosimilar monoclonal antibodies—challenges and opportunities in Europe

GaBI Journal is indexed in Embase, Scopus, Thomson Reuters’ ESCI, and more.

Readers interested in contributing a research or perspective paper to GaBI Journal – an independent, peer reviewed academic journal – please send us your submission here.

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References
1. Rutherford AI, Galloway JB. Biosimilars in rheumatology: out of the laboratory and into practice. Expert Rev Clin Immunol. 2016;12(7):697-9.
2. GaBI Online - Generics and Biosimilars Initiative. Benefits and concerns related to biosimilars [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2016 Oct 21]. Available from: www.gabionline.net/Biosimilars/Research/Benefits-and-concerns-related-to-biosimilars
3. GaBI Online - Generics and Biosimilars Initiative. EU guidelines for biosimilars [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2016 Oct 21]. Available from: www.gabionline.net/Guidelines/EU-guidelines-for-biosimilars
4. GaBI Online - Generics and Biosimilars Initiative. European regulatory pathways for biosimilars [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2016 Oct 21]. Available from: www.gabionline.net/Biosimilars/Research/European-regulatory-pathways-for-biosimilars

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