One of the hottest topics trending in specialty pharmacy is the emergence of biosimilars. In theory, biosimilars offer an opportunity to reduce medication spend for patients, payers, and pharmacies. 
 
To date, however, the acceptance and utilization of biosimilar products has largely been lagging. In order to understand why biosimilar use has been slow to gain traction within the marketplace, one must understand some of the key differences between biosimilar substitution, and that of traditionally substituted generics for brand name medications.
 
Biosimilars are defined as a biological product that is approved based on a showing that it is highly similar to an FDA-approved biological product, known as a reference product, and has no clinically meaningful differences in terms of safety and efficacy from the reference product.
 
Only minor differences in clinically inactive components are allowable in biosimilar products.  What makes these products very different from traditional medications are that the drugs themselves are far more complex. 
 
Typically, biologics are 200 to 1000 times the size of a small molecule drug, and they are manufactured in living cells. The products are then extracted and purified to make the commercially available product. 
 
Conversely, small molecule drugs are manufactured through chemical synthesis. During the formulation of biologics, protein structures are translated from DNA sequences in varying cellular environments. 
 
The types of cells used to produce a product, and the environment contained within the cells themselves during production, could potentially lead to slight variations in the final product itself. This is highly different from small molecule products, which are replicated to be chemically identical to a reference product.
 
The Biologics Price Competition and Innovation Act (BPCI Act), signed into law as part of the Affordable Care Act on March 23, 2010, paved the way for the accelerated approval of biosimilar products. Under the law, a biological product may be demonstrated as biosimilar if that data shows it is “highly similar” to an already approved biological product. 
 
Interchangeable biological products demonstrate biosimilarity to FDA-approved products and meet additional standards for interchangeability. In the case of an interchangeable product, pharmacists may substitute the generic product for the reference product without intervention of the prescriber. 

With such stringent and specific criteria required for the proper substitution of brand name biologic products, there will certainly be uncertainty on behalf of prescribers and pharmacists as products become commercially available.
 
Adding to the confusion is that each biosimilar may come to market with specific data on only a select set of information compared with the branded product. Therefore, some biosimilars will be approved for all of the indications that the reference product is approved for, while others will only be approved for the indications that they were specifically tested for in clinical trials. 
 
As more biosimilars become available in the US marketplace, pharmacists will need to work closely with prescribers to determine which patients are appropriate to begin therapy with a biosimilar, which patients are eligible to transition to biosimilars who are currently stable on branded drugs, and which products should be automatically substituted by pharmacists with no prescriber intervention.
 
Adding additional complexity to the use of biosimilar products is how prescribers will be required to write prescriptions for them. The FDA has proposed that all prescriptions for biosimilars include a suffix that follows the proper name of the product. 
 
The FDA issued guidance that the suffix should be comprised of 4 lowercase letters, be unique, and devoid of any meaning. The 4-letter suffix should not be promotional or make misrepresentations of safety or efficacy. 
 
Additionally, the suffix should not be too similar to abbreviations commonly used in clinical practice, or close to any other product’s suffix designation. In an effort to reduce confusion and aid practitioners in working with biosimilars, the FDA has created the Purple Book. 
 
The Purple Book lists biological products including biosimilar products and interchangeable biological products that have been licensed by the FDA under the Public Health Service Act. 
 
Health care providers should view the Purple Book similar to the Orange Book, which FDA has long used for therapeutic equivalence evaluations. The Purple Book includes the date a product was licensed and whether the FDA evaluated the product for exclusivity. 
 
As additional biologics are marketed generically, the Purple Book will become a valuable resource for practitioners.
 
While the transition from branded biologics to their generically available forms has been, thus far, a very slow and arguably non-existent transition, there is likely to be a paradigm shift in the mentality and utilization of these products in the near future. 
 
Specialty pharmacies will be asked to provide guidance and information on biosimilars.  Continuing the dialogue on challenges that will arise once their use becomes more commonplace is critical. Proactive work by specialty pharmacies with other health care providers will prove key to their acceptance and success. 
 
About the Author
Justin Smerker earned his PharmD degree from the University of Pittsburgh in 2009. He is currently a clinical pharmacist for PANTHERx Specialty Pharmacy. He has experience in the implementation and delivery of high-touch patient care services as well as in clinical management, persistency, and adherence programs. Justin also has participated in assisting with the successful launch of newly FDA approved medications. He has served as an adjunct clinical instructor for experiential education at Duquesne University. Prior to working in the specialty pharmacy sector, Justin successfully managed high volume retail pharmacies. He is currently enrolled in the Masters of Science in Pharmacy Business Administration (MSPBA) program at the University of Pittsburgh, a 12-month, executive-style graduate education program designed for working professionals striving to be tomorrow’s leaders in the business of medicines.