Biosimilars are not the same as generic therapies. The term “generic” has a precise meaning when it comes to medications – it is limited to small-molecule medications made from synthesized chemicals with a fixed number of atoms and a known chemical structure. A generic must be chemically identical to its branded counterpart and contain the same active ingredients. For example, the active ingredient in aspirin has only 21 atoms. Its make-up is easy to identify, and is relatively easy to copy, develop, and manufacture.1

Biosimilars are much larger molecules derived from living cells, making them challenging to develop and manufacture. For example, a human-growth hormone biologic is made up of 191 amino acids with the equivalent of around 3,000 atoms. Other more complex biologics may consist of a protein composed of over 1,300 amino acids—the equivalent of about 20,000 atoms. Many regulatory bodies have established clinical guidelines to support the development of biosimilars, laying down the requirements for demonstrating comparable pharmacokinetics, pharmacodynamics, safety and efficacy from Phase I on to controlled, randomized Phase III trials. For this reason, the cost of developing a biosimilar is between $100 million and $250 million2, but still considerably less than originator products.

1. Questions and answers on generic medicines, EMA/393905/2006 Rev 1, page 1
2. Van Arnum P. Biosimilars: market weaknesses and strengths: biosimilars represent an emerging niche in the biopharmaceutical market, but how strong is their true potential? July 11, 2012. Accessed September 20, 2013.