[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › Generics, biosimilars and bioequivalence # Generics, biosimilars and bioequivalence Why a generic medicine works like the original, how biosimilars differ from generics, and how patents and market exclusivity shape prices. Updated Nov 12, 2026 When patents and exclusivity periods end, other manufacturers can sell copies of a medicine. A small-molecule copy is a generic and must be bioequivalent to the original. A copy of a biological medicine cannot be identical, so it is approved as a biosimilar after a comparability exercise. Both lower costs and widen access. ## Key points - A generic has the same active ingredient, strength, dosage form and route as the reference medicine. - Bioequivalence means the generic delivers the same amount of active ingredient at the same rate and extent as the reference. - Generic makers do not repeat the original clinical trials, which is why generics cost less. - A biosimilar is highly similar to a reference biological medicine with no clinically meaningful differences; it is not called a generic. - Patents (granted by patent offices) and regulatory exclusivity (granted by the medicines agency) are separate protections. ## What a generic is A generic medicine is pharmaceutically equivalent to the reference product: same active ingredient, strength, dosage form and route, made to the same quality standards. Inactive ingredients, colour and shape may differ; these do not change how the medicine works, although in a few patients an excipient may affect tolerance. In the US, generics are approved through an abbreviated application that relies on the reference product's safety and efficacy data. ## Bioequivalence Two pharmaceutically equivalent products are bioequivalent when the rate and extent of availability of the active ingredient do not differ significantly under the same test conditions. In practice, pharmacokinetic studies compare how fast and how much of the drug reaches the blood after the generic and after the reference product. When they match, the two are expected to have the same clinical effect, which lets pharmacists substitute one for the other where the prescriber has not restricted it. For drugs with a narrow therapeutic range, such as phenytoin, small differences matter more, so levels or response may be followed more closely after a switch. ## Biosimilars Biological medicines, such as monoclonal antibodies, insulins and growth factors, are made in living cells and vary slightly from batch to batch, so an exact copy is impossible. A biosimilar must match the reference product in structure, biological activity, efficacy, safety and immunogenicity. Developers run comprehensive comparability studies against the reference product to show high similarity and no clinically meaningful differences, which avoids repeating the original clinical trials. EMA and the EU Heads of Medicines Agencies consider EU-approved biosimilars interchangeable with their reference and with each other; in the US, an «interchangeable» designation allows pharmacy-level substitution where state law permits. Biosimilars are monitored after approval like any other medicine. ## Patents and exclusivity - Patents are property rights granted by the patent office and can be filed at any stage of development; a new patent typically lasts twenty years from filing. - Regulatory exclusivity is granted by the medicines agency at approval and delays approval of competitors. - Examples in the US: new chemical entity, orphan drug and paediatric exclusivity, which have different lengths. - Because patents and exclusivities overlap in many ways, the date a generic can enter the market is not always predictable. - «Me-too» drugs are new molecules in an already established class; they bring a familiar mechanism in a new molecule. ## Why it matters Generics and biosimilars bring competition and lower prices, which can expand insurance coverage and treatment options. Lower cost does not mean lower quality: approved generics and biosimilars meet the same standards as the reference product. ## Test yourself Think of the answer, then tap the question to see it. ## When are two pharmaceutically equivalent products called bioequivalent? When the rate and extent to which the active ingredient becomes available do not differ significantly under the same test conditions. ## Why is a copy of a monoclonal antibody called a biosimilar and not a generic? Biological medicines vary naturally and cannot be copied exactly; the copy must be shown to be highly similar with no clinically meaningful differences. ## What may differ between a generic and the reference medicine? Inactive ingredients, colour and shape; the active ingredient, strength, dosage form and route are the same. ## How does regulatory exclusivity differ from a patent? A patent is a property right from the patent office; exclusivity is a period of protection the medicines agency grants at approval. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/topics/generics-biosimilars-and-bioequivalence/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## Example drugs - [Adalimumab](https://durgical.com/en/pharmacology/adalimumab/) - [Infliximab](https://durgical.com/en/pharmacology/infliximab/) - [Insulin glargine](https://durgical.com/en/pharmacology/insulin-glargine/) - [Filgrastim](https://durgical.com/en/pharmacology/filgrastim/) - [Trastuzumab](https://durgical.com/en/pharmacology/trastuzumab/) - [Phenytoin](https://durgical.com/en/pharmacology/phenytoin/) ## Connections ## Related classes 3 - [TNF inhibitors](https://durgical.com/en/pharmacology/classes/tnf-inhibitors/) - [Insulins](https://durgical.com/en/pharmacology/classes/insulins/) - [Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/) [← All of pharmacology](https://durgical.com/en/pharmacology/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Generic Drugs: Questions & Answers | FDA](https://www.fda.gov/drugs/generic-drugs/generic-drugs-questions-answers) (U.S. Food and Drug Administration, 2026); [Biosimilar medicines: Overview | European Medicines Agency (EMA)](https://www.ema.europa.eu/en/human-regulatory-overview/biosimilar-medicines-overview) (European Medicines Agency, 2026); [Biosimilars Basics for Patients | FDA](https://www.fda.gov/drugs/biosimilars/biosimilars-basics-patients) (U.S. Food and Drug Administration, 2026); [Frequently Asked Questions on Patents and Exclusivity | FDA](https://www.fda.gov/drugs/development-approval-process-drugs/frequently-asked-questions-patents-and-exclusivity) (U.S. Food and Drug Administration, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/topics/generics-biosimilars-and-bioequivalence/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/topics/generics-biosimilars-and-bioequivalence/