Biosimilars provide an opportunity to treat a larger number of patients while at the same time reducing healthcare expenditure . However , the interpretation of interchangeability and rules around switching differ between healthcare systems across the globe leading to variability in access to care as discussed in this article

Tiene Bauters PhD PharmD Clinical Pharmacist , Pharmacy Dept , Ghent University Hospital , Ghent Belgium

A fundamental pillar of healthcare is access to effective , safe and affordable medicines . Biosimilars are highly similar versions of existing biologics ( originators or reference products ( RPs )) in terms of efficacy , quality and safety . 1 , 2

Over the past decade , the market exclusivity of many originators expired , leading to an increasing number of biosimilars entering the market . Due to the potential for enormous cost savings , the introduction of biosimilars is beneficial for patients ( enabling wider access to treatment ) and healthcare budgets . However , their use is accompanied by changes in practice within healthcare institutions . 1 – 4

The Food and Drug Administration ( FDA ) in the United States ( US ) and the European Medicines Agency ( EMA ) in Europe have the regulatory responsibility of biosimilarity . Consequently , there is an assurance that the products are both safe and effective for all the licensed indications defined in the Summary of Product Characteristics . However , prescribers are free to initiate treatment in a newly diagnosed patient with either the RP or a biosimilar . 1 , 2

Despite this assurance , even after years of positive experience with biosimilars , there is still an on-going debate as to whether or not biosimilars can be considered interchangeable with their RP or with other biosimilars of the reference product . 3 – 9 The likelihood of patients needing to switch from an RP to a biosimilar or from one biosimilar to another is also expected to increase . 3

As such , healthcare providers should be aware of the terminology used to define interchangeability , substitution and switching as these terms might be interpreted differently . 4 , 5

In this article , the following definitions are used .

Definition and concept of switching / substitution Switching is defined as a decision by the treating physician to exchange one medicine for another with the same therapeutic intent in patients for their treatment . 1

Switching can be done for medical reasons ( medical switching ), at the physician ’ s discretion with the aim of optimising the patient ’ s treatment benefit . 3 This can be undertaken because of a change in disease activity , issues of tolerability ( e . g . the avoidance of irritating excipients ), adverse events , 3 , 7 or to enable a more beneficial administration for the patient or their caregiver .

Non-medical switching occurs in clinically stable patients to a therapeutic alternative , mainly to mitigate costs or to

TABLE 1

Overview of definitions , requirements and regulations of switching and substitution of biosimilars in the US and Europe . 1 – 5

US Europe

Requirements No regulatory requirements No central requirements

Regulatory level State level Member states

Requirements

Product level interchangeability designation by the FDA

No central requirements

Regulatory FDA , State level laws EU member states

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