Some fashion trends may come and go, but in the not too distant future the majority of prescription drug sales will be purple.
For those of you not yet familiar with this latest trend, allow me to explain.
Most drug products are small, synthetically produced substances. The common pain reliever ibuprofen, for example, contains only 33 atoms and has a molecular weight of 206. In contrast, there is a whole new class of complex drug products that are isolated or produced from biological sources such as living cells. These biologically produced drugs, more commonly called “biologics”, are orders of magnitude larger than their small molecule cousins and present special challenges in their preparation, isolation, and administration. Insulin is a common example of a biologic. It is a protein having a molecular weight of approximately 5800. Another example is the hormone erythropoietin (or “EPO”), which is used to treat anemia. EPO is a far larger biological drug with a molecular weight of nearly 35,000.
So what does this have to do with the color purple?
First, Enter The Orange Book
Small-molecule prescription drugs are approved by the US Food and Drug Administration (FDA). In 1984, Congress passed the Drug Price Competition and Patent Restoration Act (commonly known as “Hatch-Waxman”) to bring low-cost prescription drug products to consumers, while balancing the competing interests of the branded pharmaceutical industry and generic drug manufacturers. Hatch-Waxman provided a unique statutory link between the patent and regulatory systems and established a framework under which generic drugs could be marketed. Hatch-Waxman requires the FDA to publish information on approved drug products with their therapeutic equivalence information. Also published are patent and other exclusivity information for the approved drugs, setting the grounds for the complex litigation that results when the interests of the branded and generic drug manufacturers clash. The FDA publication in which this drug and patent information appears is known, not by its lengthy title, but rather by its distinctive orange cover – hence, the “Orange Book”.
Now Enter the Purple Book
Fast forward to 2014, or rather first to 2010. In March of that year, President Obama signed into law the Patient Protection and Affordable Care Act (more commonly known as “Obamacare”). One of the Act’s provisions was the Biologics Price Competition and Innovation Act (“BPCIA”), which created an abbreviated licensure pathway for biologics that are demonstrated to be either “biosimilar” to or “interchangeable” with the originally approved product. In other words, the legislation created a regulatory pathway for the approval and marketing of the generic equivalent of a biological drug. This regulatory pathway is just getting off the ground. Even though biologics have been around for a long time (synthetic insulin was marketed in 1982), no biosimilar product has as yet been approved in the United States. In fact, it is believed that only two biosimilar applications are currently pending before the FDA. However, this will all soon change and the first biosimilars are expected to receive approval in 2015.
Since the passing of the BPCIA, the FDA has issued various announcements on biologics and biosimilars, including a long-awaited Draft Guidance that was published in August. The big news, however, is that the FDA just published its first edition of the Purple Book, with the lengthy title – “Lists of Licensed Biological Products with Reference Product Exclusivity and Biosimilarity or Interchangeability Evaluations”. This publication, like its Orange Book Counterpart, lists approved biological drug products and will eventually list biosimilar and interchangeable products as they are approved. The published information, however, is still not complete. For example the date of first licensure and the expiry of product exclusivity are only listed for three products. Clearly, the FDA has much work ahead to compile complete information.
Will There Be A Color Clash?
It will be interesting to see how the Purple Book will function. Will it clash with the Orange Book? After all, orange and purple are not exactly complementary colors. Only time will tell as biologics overtake the pharmaceutical market and the first biosimilar and interchangeable products begin receiving approval.
 As explained in this article, biologically produced drugs (“biologics”) will be governed by the US Food and Drug Administration’s (FDA’s) newly established “Purple Book”. Depending on the source and how the data is analyzed, biologics accounted for just 10 percent of annual prescription drug sales in 2010. By 2017, that number could well surpass 50 percent. Notwithstanding the data, the trend is clear that biologics will account for a majority of prescription drug sales.
 Approved Drug Products with Therapeutic Equivalence Evaluations
 “Biosimilars” and “Interchangeables” are two different types of biological generic products. This distinction and its implications will be the topic of a future article.