On Tuesday, the US Food and Drug Administration released a draft biosimilar interchangeability guidance document, something that industry has been waiting on for over a year. Biosimilar drug manufacturers will now have 60 days to review the draft and submit any comments to the FDA, before the agency forms its final interchangeability rules.

The main takeaway for sponsors is that, in general, the FDA considers switching studies to be the most effective way to demonstrate interchangeability. These studies are conducted to show that alternating between a biosimilar and the reference drug, two or more times, has no impact on safety or efficacy of the treatment course.

However, the agency has stressed that requirements will vary depending on the product submitted. For example, if a product is intended to be administered only once, or if sponsors can provide adequate extrapolated data to support interchangeability for multiple indications, then it would not be necessary to conduct a switching study.

The FDA says it will consider several factors when determining the type and amount of submission data needed for a particular product, including the complexity and intended use of the drug. As such, there is no one size fits all package that will work for all biosimilar submissions, and the FDA recommends that sponsors consult with the agency early on to discuss the most appropriate course of action.

The FDA also stresses in the guidance document that presentation is a key factor when it comes to reviewing an interchangeability submission. In general, sponsors should try to replicate the presentation of the reference product as closely as possible. This means that the drug should have a similar delivery device and container closure system. The FDA believes that it is important to minimize differences in presentation between the two products, as any visual differences could raise uncertainty among patients about whether the biosimilar does indeed have the same effect as the branded drug.

This FDA guidance on interchangeability comes at an important time for the biosimilar drug industry. Although interchangeability isn’t required for the approval of a biosimilar drug, it does allow a pharmacist to fill a patient’s subscription with that product, rather than the branded product, without having to receive approval from the prescribing doctor. This will be increasingly beneficial for biosimilar manufacturers, as many of the world’s top-selling drugs have patents that are set to expire in the coming years.