Biosimilars vs Generics: Key Differences Explained

While often mentioned together, biosimilars and generics are distinct types of medications, and understanding the difference can support more informed treatment planning and cost management. Both provide opportunities to improve patient access once brand patents expire, but they approach this goal differently.

Biosimilars, introduced to the U.S. market in 2015, are highly similar to existing biologic drugs. They are designed to match the original in safety, quality, and efficacy, while offering potential cost savings. Their use requires careful oversight and monitoring, especially for specialty infusion therapies, to ensure consistent outcomes for patients with complex conditions.

Generics, in contrast, are exact chemical copies of brand-name drugs. They are generally simpler to produce than biosimilars, which often translates into broader affordability and accessibility for patients.

For health systems and providers, distinguishing between biosimilars and generics informs treatment decisions, formulary management, and care coordination strategies. Specialty pharmacies like CSP play a crucial role in integrating these alternatives into therapy plans, monitoring patient response, and providing data-driven insights to support both clinical and operational outcomes.

Generic Medications

Generic medications are chemically identical to their brand-name counterparts, containing the same active ingredient, strength, and dosage form. When a branded drug’s patent expires, other manufacturers can produce generics without repeating the extensive research and development process, making them more affordable—often up to 85% less than the original.

Consistency is key: every batch of a generic is virtually identical to the original, ensuring predictable, reliable outcomes for patients. Regulatory evaluation focuses on demonstrating similar bioavailability, meaning the generic delivers the same amount of active ingredient to the bloodstream at the same rate as the brand-name drug. This ensures therapeutic equivalence while supporting safe, effective care.

For patients managing complex or chronic conditions, generics offer dependable, cost-effective treatment options. Specialty pharmacies play an essential role in integrating generics into care plans, coordinating medication delivery, monitoring patient response, and providing actionable data to support both clinical outcomes and operational efficiency.

Biosimilars

Biosimilars represent a newer category of medications designed to be highly similar to existing biologic drugs. Unlike generics, biosimilars aren’t exact copies. Biologics are large, complex molecules produced by living organisms, making them impossible to duplicate exactly. Instead, biosimilar manufacturers must demonstrate that their product has no clinically meaningful differences from the reference biologic in terms of safety, purity, and potency.

Creating a biosimilar involves reverse-engineering the reference biologic’s production process. Manufacturers must develop their own cell lines and manufacturing methods to produce a product that matches the original as closely as possible. This process typically takes 8-10 years and costs hundreds of millions of dollars—far more than generic drug development.

Biosimilars face a much more comprehensive evaluation process. Regulators examine everything from the molecular structure and biological activity to clinical performance, backed up by clinical studies.

How Generic Drugs and Biosimilars Are Manufactured

While both generic drugs and biosimilars provide cost-effective alternatives to branded medications, the processes behind their production differ significantly due to their molecular complexity.

Generic medications are created through precise chemical synthesis in controlled laboratory settings. With decades of industry experience, manufacturers can reliably produce exact copies of brand-name drugs. These small-molecule medications are relatively straightforward to replicate, ensuring consistent strength, dosage, and effectiveness across batches.

Biosimilars, by contrast, are derived from living cells, such as bacteria, yeast, or mammalian cells that are genetically engineered to produce specific molecules. Because biologics are large and complex, biosimilars cannot be identical to their reference products—they are highly similar versions designed to achieve the same clinical outcomes. This complexity requires sophisticated development, rigorous testing, and careful monitoring throughout manufacturing to ensure quality, safety, and efficacy.

Drug Evaluation

The evaluation process for generics and biosimilars reflects their fundamental differences in complexity and manufacturing. Both types of medications must meet rigorous standards, but the pathways to approval vary significantly based on the nature of the drugs themselves.

The FDA Approval Process for Generics

The FDA approval process for generic medications follows the Abbreviated New Drug Application (ANDA). This streamlined process recognizes that generics don’t need to repeat the safety and efficacy studies already completed for the brand-name drug. Instead, manufacturers must prove their product is pharmaceutically equivalent and bioequivalent to the reference drug.

Here are some key points about generic approvals:

Generic must contain the same active ingredient in the same dosage form and strength
It must meet the same quality standards for purity, strength, and manufacturing
Bioequivalence testing typically involves 24-36 healthy volunteers to measure drug concentrations in the blood over time
The entire process usually takes 3-4 years from development to approval
Once approved, most generics can be automatically substituted for brand-name drugs at the pharmacy level in most states

This automatic substitution has been crucial in making generic medications widely accessible and keeping healthcare costs down.

The FDA Approval Process for Biosimilars

Biosimilars follow a different regulatory pathway through the Biologics License Application (BLA) under section 351(k) of the Public Health Service Act. This process requires manufacturers to demonstrate biosimilarity through comprehensive analytical and clinical data.

Here are some important points about the biosimilar approval process:

Manufacturers must show their biosimilar has the same amino acid sequence as the reference product and similar higher-order structures, biological activities, and product variants
Any differences must be justified and shown not to affect clinical performance
Clinical studies for biosimilars typically include at least one comparative clinical trial in patients.
The entire development and approval process for a biosimilar typically takes 7-8 years and costs $100-200 million

Dosage Form and Active Ingredients

Generic drugs are designed to achieve true bioequivalence with their brand-name counterparts. Each generic contains the same active ingredient in the same strength—for example, a 50 mg tablet of a brand-name drug will have an identical 50 mg of the active compound. While inactive ingredients such as fillers, coatings, or colors may differ, these variations do not affect the drug’s therapeutic performance.

Biosimilars, in contrast, cannot replicate biologics exactly due to the inherent variability of living systems. Even batches of the same biologic exhibit minor differences in molecular structure, folding, or glycosylation patterns. Despite these natural variations, biosimilars are rigorously tested to ensure they deliver the same clinical outcomes as the reference biologic in terms of safety, purity, and potency.

How to Ensure Consistent Delivery and Outcomes

Generics match brand-name drugs not only in composition but also in dosage form. Tablets, capsules, or infusions must follow the same delivery method to maintain effectiveness. Extended-release forms must release the active ingredient at the same rate to preserve dosing schedules and patient outcomes to be considered therapeutically equivalent and interchangeable by the FDA.

Quality control is central to both generics and biosimilars. For generics, this focuses on chemical purity, consistency, and stability across batches. For biosimilars, rigorous analytical and clinical testing ensure that each batch meets strict standards for safety and efficacy.

Specialty pharmacies need to support providers in integrating both generics and biosimilars into patient care safely and effectively. Through precise handling, monitoring, and patient education, they can help maintain adherence, optimize treatment outcomes, and ensure seamless transitions between therapies.

Interchangeability and Substitution in Prescription Drugs

Understanding how generics and biosimilars can be substituted for their reference products is critical for both patient care and operational efficiency. These rules shape what happens at the pharmacy counter and influence timely access to medications.

Generic Substitution

Generic substitution is a well-established practice. When a prescriber writes a brand-name prescription, pharmacists can automatically dispense an FDA-approved therapeutically equivalent generic unless the prescriber or state/federal regulation does not allow. This streamlined process supports patient access, reduces costs, and encourages adherence.

Pharmacy substitution rules for generics are consistent across most states. Pharmacists are required to inform patients when they receive a generic in place of the brand-name drug. Each generic must meet FDA bioequivalence standards, ensuring the same clinical effect as the reference product. This approach helps payors manage costs while maintaining high-quality care.

Biosimilars and Interchangeability

Biosimilars follow a different substitution framework. Most cannot be automatically substituted at the pharmacy level. Only those that receive the FDA designation of “interchangeable” may be switched with their reference product without consulting the prescriber, per state and federal regulations.

Interchangeable biosimilars must demonstrate that repeated switching with the reference biologic does not affect safety or efficacy. As of 2024, only a limited number of biosimilars have earned this designation. State laws vary, with some allowing pharmacy-level substitution while others require prescriber notification or consent.

Implications for Specialty Pharmacies

Specialty pharmacies like California Specialty Pharmacy help ensure that these regulations do not create barriers to care. Through close collaboration with prescribers, pharmacists, and care teams, CSP supports safe and timely access to both generics and biosimilars. By managing medication selection, delivery, and patient education, specialty pharmacies reduce the risk of treatment interruptions, optimize adherence, and help healthcare systems achieve better outcomes efficiently. They can also play a role in lowering the overall cost of care for both patients and payors by facilitating the use of cost-effective alternatives where it makes sense.

Economic Impact

The introduction of generics and biosimilars has fundamentally changed the economics of healthcare. Both create competition that drives down prices, but they do so in different ways and to different degrees.

When generics enter the market, prices typically drop by 80-90% compared to the brand-name drug. This dramatic reduction happens quickly, often within months of patent expiration. Multiple generic manufacturers can produce the same drug, creating robust competition.

Biosimilars create a different competitive dynamic. Because they’re more cost-intensive to develop and manufacture, fewer companies enter the biosimilar market for any given reference product. Price reductions are more modest (typically 15-35% initially), though costs may be reduced over time as more biosimilars become available.

Generics Drive Immediate Cost Reduction

Generic medications have become the backbone of affordable healthcare in the United States. In 2023 alone, generics saved the healthcare system over $440 billion. Patients pay less out of pocket, insurance premiums stay lower, and government programs can treat more people with the same budget.

The pharmaceutical industry has adapted to this reality by focusing innovation on new drugs while accepting that older medications will face generic competition. This cycle of innovation and competition has created a sustainable model where companies can recoup research investments while medications eventually become affordable for everyone.

Biosimilars Create Gradual Savings

Biosimilars are beginning to transform the biologics market, though more gradually than generics changed small-molecule drugs. The impact varies by therapeutic area. In oncology, biosimilars have driven down the cost of critical cancer treatments. In rheumatology, biosimilar versions of drugs like adalimumab and infliximab provide more affordable options for patients with autoimmune conditions.

Competition Is Good For Everyone’s Health

Generic drugs will continue to make routine treatments affordable for millions. Biosimilars will increasingly provide access to advanced biologic therapies that were once financially out of reach for many patients. Together, they create a more sustainable healthcare system.

California Specialty Pharmacy remains committed to helping patients access both biosimilars and generics for their specialty infusion needs. Our expertise in navigating insurance coverage, managing complex therapies, and supporting patients makes us an invaluable partner in a patient’s healthcare journey.

Get started today as a healthcare system partner.

Frequently Asked Questions (FAQ):

What are the advantages of biosimilars over generic drugs?

Biosimilars are more complex and can offer treatment options closer to the original biologic, potentially improving therapeutic outcomes in certain cases.

What are some examples of biosimilars?

Examples of biosimilars include Zarxio (filgrastim-sndz), Inflectra (infliximab-dyyb), and Erelzi (etanercept-szzs).

What is considered a biosimilar?

A biosimilar is a biologic medical product highly similar to an already approved reference biologic, with no clinically meaningful differences in terms of safety, purity, and potency.

What is another name for biosimilars?

Biosimilars are also referred to as follow-on biologics or subsequent entry biologics.

References:

Generic Drugs: Questions & Answers. U.S. Food & Drug Administration (FDA).
https://www.fda.gov/drugs/frequently-asked-questions-popular-topics/generic-drugs-questions-answers
Price G, Patel DA. Drug Bioavailability. StatPearls Publishing.
https://www.ncbi.nlm.nih.gov/books/NBK557852/
Feng K, Russo M, Maini L, Kesselheim AS, Rome BN. Patient Out-of-Pocket Costs for Biologic Drugs After Biosimilar Competition. JAMA Health Forum.
https://jamanetwork.com/journals/jama-health-forum/fullarticle/2816952

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