Substitution by pharmacists of one product with another that has the same INN (International Non-proprietary Name) is common practice with generic drugs in many EU countries.

But is substitution appropriate with biologicals? Unlike more common small-molecule drugs, biologicals generally exhibit high molecular complexity and micro-heterogeneity. Biologicals are also very sensitive to manufacturing process changes, including the choice of the cell type, along with production, purification and formulation processes. In view of the complexity and sensitivity of biologicals to the manufacturing process, no two biotech medicines can be exactly the same, hence the term ‘biosimilar’ and not biogeneric. As a consequence of their complexity, automatic substitution of biologicals could give rise to different clinical consequences and therefore many believe that this should be ruled out for reasons of patient safety [1].

Several European substitutions and agencies, including the EMA, have advised that the decision to treat a patient with a biosimilar medicine should be taken following the opinion of a qualified healthcare professional.

Measures to prevent automatic substitution of biosimilars are already in place in several European countries and others have taken steps to limit the practice (see Box). Substitution is also on the agenda in other regions, such as Canada, where automatic substitution is not recommended, and in the Middle East, where it has been recommended that products should be clearly identified as biosimilar on the label.

But is this practice of preventing automatic substitution protecting patients or is it restricting access to affordable medicines? The debate will surely go on. The challenge for biosimilars manufacturers is to prove that their products are indeed equivalent or even better than the originator biological.

Reference

1. Niederwieser D, Schmitz S. Biosimilar agents in oncology/haematology: from approval to practice. Eur J Haematol. doi: 10.1111/j.1600-0609.2010.01566.x