Less expensive, “generic” versions of biologic medications are a step closer to appearing on pharmacy shelves – although the road to federal approval of so-called “biosimilars” could still be a long one.

The U.S. Food and Drug Administration (FDA) in 2012 released draft guidelines that define the oversight and approval process for companies that want to make and sell biosimilars. These medications will be similar substitutes for biologic products already used to treat a variety of conditions, including rheumatoid arthritis, cancer and diabetes.

A new approval pathway is needed for biosimilars because, unlike most medications, which are made from chemical molecules, biologics are proteins produced by gene-based technology from biological components such as living animal, or human or microorganism cells. So, unlike generic forms of chemical drugs, they are not exact replicas of the original drug.

“The protein has a complicated, three-dimensional structure and it’s much larger than a regular chemical drug, so it’s very tricky to make it exactly the same way every time,” explains Donald Miller, professor and chair of pharmacy practice at North Dakota State University in Fargo. “The original manufacturer has a patent on the process to make the protein, and they put in a lot of work to make it reproducible, so someone starting from scratch has a lot of work to do to make the identical protein.”

A provision in the federal health care reform law, signed by President Obama in March 2010, mandated the creation of an abbreviated regulatory pathway for the approval of biosimilars. To come up with that pathway, the FDA met with pharmaceutical companies and other interested parties (including patient advocates and doctors) and held hearings. The draft guidelines are result of that process. They outline the scientific and quality expectations the FDA has of any drug company making a biosimilar, such as how similar it must be and what safety studies must be conducted.

The FDA says the exact requirements, to be determined on a case-by-case basis, will vary from one product to the next. Small differences in drug formulation, delivery devices and containers will be allowed, but those differences cannot be clinically meaningful from the original, or “reference” product. The government reserves the right to require clinical trials if it deems them necessary – something not required of most generic drugs.