Interchangeability is also defined differently in different countries and regions. In the European Union (EU) interchangeability is defined as ‘the medical practice of changing one medicine for another that is expected to achieve the same clinical effect in a given clinical setting and in any patient on the initiative, or with the agreement of, the prescriber’ [2].

Replacement of one product by another can be achieved by switching, which is a decision made by a physician, or by (automatic) substitution at the pharmacy level. However, in Canada and the US, interchangeability refers to automatic substitution but not switching. In the US, ‘the biological product may be substituted for the reference product without the intervention of the healthcare provider who prescribed the reference product’ [2]. Whereas in Canada, the authorization of a biosimilar is not a declaration of equivalence to the reference biological. Decisions on interchangeability are made by each province and territory according to its own rules and regulations.

The different policies in use in different countries around the world was investigated in a survey carried out by World Health Organization (WHO) in 2019‒2020, see Table 1 [3]. The survey found that in most of the participating countries, interchangeability refers to switching and automatic substitution is not accepted. In fact, the survey found that automatic substitution of biosimilars was practised only in Iran and Japan.

The survey revealed that most countries do not have regulatory guidelines for the interchangeability of biosimilars, but many have adopted national approaches for this.

In the European Union (EU), decisions on the interchangeability or substitution of biosimilars and originator biologicals are not made by the drug regulator, the European Medicines Agency (EMA), but at the national level. This is despite the fact that biosimilars developed in line with EU requirements are considered by EMA to be therapeutic alternatives to their reference biologicals. This means that automatic substitution of biosimilars is generally not routinely practised [5].

Consequently, several EU countries have issued national guidance, for example, Denmark, Finland and the Netherlands. In addition, medical health societies in the EU have provided guidance on switching from an originator product to the corresponding biosimilar. Particularly in Nordic countries, massive non-medical switches with the supervision of prescribing physicians have taken place due mainly to the purchase of biosimilars by bulk tenders [6].

Conflict of interest
The authors of the research paper [3] declared that there was no conflict of interest.

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

European prescribers’ attitudes and beliefs on biologicals prescribing and automatic substitution

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References
1. GaBI Online - Generics and Biosimilars Initiative. Interchangeability of biosimilars around the world [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2021 Mar 5]. Available from: www.gabionline.net/Reports/Interchangeability-of-biosimilars-around-the-world 
2. Derbyshire M. USA and Europe differ in interchangeability of biosimilars. GaBI Journal. 2017;6(4):183-4. doi:10.5639/gabij.2017.0604.039
3. Kang HN, Thorpe R, Knezevic I, et al. Regulatory challenges with biosimilars: an update from 20 countries. Ann N Y Acad Sci. 2020 Nov 21. doi: 10.1111/nyas.14522. Epub ahead of print.
4. GaBI Online - Generics and Biosimilars Initiative. Ontario becomes third Canadian province to switch patients to biosimilars [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2021 Oct 5]. Available from: www.gabionline.net/biosimilars/general/Ontario-becomes-third-Canadian-province-to-switch-patients-to-biosimilars
5. GaBI Online - Generics and Biosimilars Initiative. Biosimilar substitution in Europe [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2021 Mar 5]. Available from: www.gabionline.net/Reports/Biosimilar-substitution-in-Europe 
6. GaBI Online - Generics and Biosimilars Initiative. Switching approaches to biosimilars in Nordic countries [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2021 Mar 5]. Available from: www.gabionline.net/Reports/Switching-approaches-to-biosimilars-in-Nordic-countries

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