Biosimilar vs generic: which is better?

Biosimilar drugs are often confused with generic drugs. Biosimilars and generic drugs are versions of brand-name drugs and may offer cost-saving treatment options to patients. Brand manufacturers begin with exclusivity protection for many years to allow them to profit from their research and development of the drug. During this time no biosimilars or generics can compete with the brand. After patent expiry, biosimilars and generics can enter and gain market share.

Biosimilars and generics are both approved by the U.S. Food and Drug Administration (FDA) but biosimilars require a specific regulatory approach distinct from that of generics. The Biologics Price Competition and Innovation Act of 2009 shortened the FDA approval process for biosimilar drugs to avoid duplicating costly clinical trials.

Biosimilars are not generic medicines, and there are important differences between biosimilars and generic drugs. Read on to find out more.

What is a biosimilar drug?

It is a biological product that is very similar to another biological product known as the reference biologic (the original biologic drug).

e.g. the brand product Humira used to treat rheumatoid arthritis is the reference biologic and Amjevita is its biosimilar product manufactured by Amgen.

Biosimilar medicines have certain features:

  • Large complex molecules make them challenging and costly to produce
  • Biological medicines originate from living cells, such as humans, animals, or microorganisms, so they have sophisticated and costly manufacturing processes
  • Highly similar to the reference product but can not be identical as these drugs originate from living cells
  • Minor differences to the reference product within strict limits
  • A biosimilar has no clinically meaningful differences in safety, purity, and effectiveness from an existing FDA-approved reference product
  • Biosimilars are more complicated to develop and the FDA regulatory pathway for approval is more complex

Biological products can include a wide range of products including vaccines, blood components, gene therapy, tissues, and proteins, like monoclonal antibodies and cell signaling proteins.

What is a generic drug?

A generic drug is a medicine that contains the same active ingredient as the branded medicine and is a chemical copy of the branded drug.

e.g. the brand name drug Glucophage is used to treat diabetes but its generic drug product is metformin.

Generic drugs have certain features:

  • Small molecule structures
  • Its manufacturing process is easy and predictable
  • Created in a laboratory with chemically identical ingredients to their reference products
  • Provides the same clinical benefit as the brand name medicine
  • Minor differences to the reference product within strict limits
  • They go through FDA approval to show their safety and effectiveness.

Another important difference that clearly sets biosimilars and generics apart is interchangeability. The approval of a drug as a biosimilar does not automatically mean it is interchangeable with its reference product. A pharmacist can not substitute a biosimilar product with another product, unlike generics that can be automatically substituted with other generic versions. According to the FDA, a biosimilar product cannot be substituted at the pharmacy level without the intervention of the prescribing healthcare provider. For biosimilars to be approved as interchangeable, they must meet further criteria during the approval process, unlike generics.

Key differences between generic drugs and biosimilar drugs

FDA definitionA biosimilar is highly similar to its reference biological product and has no clinically relevant differences to the reference product in terms of safety, purity, and potencyA generic drug is identical to a branded drug in dosage form, safety, strength, route of administration, quality, performance characteristics, and intended use
Size & structureLarge and complexSmall and simple
ManufacturingBiological process using living cells Chemical synthesis using chemical ingredients in an ordered sequence
Administration routeInjectionOral
StabilityUnstable as sensitive to handling and storage conditionsStable
FDA approval processPreclinical (animal) and clinical (human) data to establish safety and effectiveness are generally requiredPreclinical (animal) and clinical (human) data to establish safety and effectiveness are generally not required
Reference medicationReference drug ( the original) is an FDA approved biologicReference drug (brand name medication) is an FDA approved drug
NamingEach biosimilar has its own brand name consisting of the same non-brand name of the reference biologic plus a suffix of four lower case letters e.g. infliximab-axxq its reference product is Remicade (infliximab) The generic drug has the same chemical/active ingredient as the branded drug

Medically reviewed

A medical professional has reviewed this article.

Jamie Winn, PharmD
Jamie Winn, PharmD

Jamie Winn, PharmD

Medical Writer & Reviewer

Jamie Winn, PharmD

Medical Writer & Reviewer

Dr. Jamie Winn received his Doctor of Pharmacy in 2002 from the University of South Carolina College of Pharmacy, Columbia, SC. Jamie is a medical reviewer for NiceRx.

Share this page

Other articles on

Sources (5)

  1. National Library of Medicine - How Similar Are Biosimilars? What Do Clinicians Need to Know About Biosimilar and Follow-On Insulins?

  2. FDA - Biosimilar and Interchangeable Products

  3. FDA - FDA’s Overview of the Regulatory Guidance for the Development and Approval of Biosimilar Products in the US

  4. FDA - Purple Book: Lists of Licensed Biological Products with Reference Product Exclusivity and Biosimilarity or Interchangeability Evaluations

  5. US Pharmacist - Biosimilars: Not Simply Generics

The content on this website is intended for information purposes only. It does not constitute medical advice. The information on this website should not be relied upon and is not a substitute for professional medical advice. You should always speak to your doctor regarding the risks and benefits of any treatment.
NiceRx Logo

Your medication,
$49 per month

Get your medication for only $49 per month through NiceRx.

Get Started