Why pharmacists are concerned about the safety of biosimilars
Pharmacists, physicians, and other healthcare professionals are rightly concerned about the safety and efficacy of biosimilar drugs. Because they are so new on the market—only two have been approved in the U.S. to date—their safety has not been proved.
In addition, healthcare professionals are looking to the FDA for more guidance. To date, the agency will only say that biosimilars are “highly similar” to their reference products. In other words, they are not completely interchangeable as generics are.
“Since a biosimilar drug is not identical to the reference innovator product, the efficacy and safety data generated for the latter cannot be directly and completely transferred to the biosimilar. Both its efficacy in various therapeutic indications and its safety profile in diverse risk populations may be different from that of the innovator,” said Suhasini Sharma, director of medical affairs for Sciformix Corporation, in the company’s white paper Pharmacovigilance and Risk Management for Biosimilars: Unique Challenges and Possible Solutions.
Biosimilars are “highly similar to an already FDA-approved biological product, known as the biological reference product (reference product), and have been shown to have no clinically meaningful differences from the reference product,” according to the FDA in its notice Information for Healthcare Professionals: Biosimilars. “Minor differences in clinically inactive components are allowed. But there must be no clinically meaningful differences between the biosimilar and the reference product it was compared to in terms of the safety, purity, and potency of the product.”
On the other hand, interchangeable products are both biosimilar to an FDA-approved reference product and can be expected to produce the same clinical result as the reference product in any given patient, according to the FDA. “An interchangeable product may be substituted for the reference product without the intervention of the health care provider who prescribed the reference product. In addition, for a biological product that is administered more than once to an individual, the risk in terms of safety or efficacy of alternating or switching between the biological product and the reference product will not be greater than the risk of using the reference product without alternating or switching.”
Before doctors will prescribe new biosimilars, they need assurances from the FDA that the drugs are substitutable, as is the case with branded versus generic drugs, said Robert T. Adamson, PharmD, chief pharmacy officer, corporate pharmacy, Barnabas Health, West Orange, NJ.