Bioequivalence (BE) studies are essential for generic drug development, demonstrating that generics deliver the same active ingredients as brand-name drugs. This process allows for regulatory approvals through abbreviated pathways, increasing competition and patient access to affordable medications. However, the bioequivalence landscape is evolving due to harmonized global standards and advanced modeling techniques. The global market for bioequivalence studies, worth approximately USD 865 million in 2025, is expected to grow to USD 1.87 billion by 2035, driven by increased generic drug approvals and regulatory standardization.
Zenovel provides comprehensive bioequivalence study services, aiding generic manufacturers in confidently navigating emerging trends.
Global Regulatory Harmonization Through ICH M13A
The implementation of the ICH M13A guideline on January 25, 2025, represents a key regulatory development, as it harmonizes bioequivalence standards for immediate-release solid oral dosage forms (tablets, capsules, and granules/powders for oral suspension) adopted by both the FDA and EMA.
Key provisions include:
- Streamlined Study Requirements: For many non-high-risk drugs, only one appropriate BE study is now required, eliminating the need for both fasting and fed condition studies.
- Structured Framework: The guideline offers recommendations for study design, analytical methodologies, and statistical approaches that meet local and global regulatory standards.
- Global Harmonization: BE studies initiated post-implementation must adhere to ICH M13A across ICH regions, minimizing regulatory and development redundancies.
- Series Approach: ICH M13A is the initial guideline in a series focusing on the scientific and technical aspects of BE assessment for orally administered immediate-release (IR) solid dosage forms. ICH M13B introduces biowaivers for additional strengths, enabling generic applicants to obtain approval for multiple drug strengths without extensive in vivo testing, contingent on meeting specific scientific criteria.
- Health Canada: On December 27, 2025, ICH M13A was implemented, and the EMA has been updating bioequivalence guidelines to comply with this new standard.
The impact for generic manufacturers includes streamlined development, reduced regulatory costs, and harmonized scientific expectations across global markets.
Modeling and Simulation (MBBE and PBPK)
Traditional bioequivalence assessment using Non-Compartmental Analysis (NCA) has notable limitations, including low statistical power and the need for large sample sizes for various drug classes, which hinders the availability of affordable generics.
- MBBE demonstrates a significant reduction in required sample size by 45% in a study of a moderately variable oral drug, reducing the number from 44 to 24 while maintaining target power. This effect is expected to be more pronounced in complex scenarios like parallel designs for long-acting injectables, highly variable drugs, and ophthalmic products.
- Physiologically Based Pharmacokinetic (PBPK) modeling is increasingly recognized in generic drug development, with recent FDA approvals showcasing its support for alternative bioequivalence approaches, notably in the case of generic diclofenac sodium topical gel, 1%.
- The FDA’s GDUFA Science and Research Priority Initiatives for Fiscal Year 2026 emphasize the agency’s commitment to modeling and simulation as key tools in its operations.
- Enhancing formulation and device design, improving PK study design and efficiency, and extending efficiency and speed benefits earlier in the development cycle are key objectives.
- Model-Integrated Bioequivalence (MIBE) approaches, especially population PK-based methods, are under investigation to address regulatory questions regarding bioequivalence (BE) across various formulations. The FDA is promoting research to enhance the use of model-integrated evidence in demonstrating BE.
Complex Generics
While simple immediate-release oral tablets are foundational in the generic industry, the future focus is on complex generics, which include intricate active ingredients and drug-device combinations. Traditional bioequivalence standards, tailored for small-molecule drugs, are becoming inadequate due to the rising complexity of drug products, such as long-acting injectables and modified-release formulations.
Major challenges for complex generics include:
- Estimating absorption for locally acting products, like inhaled or topical drugs, is complex due to the limitations of systemic pharmacokinetics in reflecting local delivery and effectiveness.
- Advanced characterization requires additional in vitro tests, including particle size distribution, dissolution profiles, and microstructure analysis, to demonstrate sameness in critical quality attributes beyond standard PK.
- Complex products demonstrate significant variability and sensitivity, primarily arising from potential manufacturing variations, excipient interactions, or inconsistencies in devices.
- Alternative study designs may be necessary, as traditional crossover PK studies can be inadequate. Options include pharmacodynamic studies, comparative clinical endpoint studies, in vitro-in vivo correlations, virtual BE modeling, or combined approaches.
The FDA prioritizes complex generics, urging the use of systematic, science-based methodologies that rely on accurate, sensitive, and reproducible methods.
Enhanced Data Integrity Requirements
Data integrity is a vital regulatory concern, highlighted by the FDA’s March 2025 findings of significant issues in bioequivalence studies by a CRO. The Bioequivalence Working Group for Generics is tackling these problems, with a report shared among regulatory agencies, which are intensifying their scrutiny of such studies.
Population PK modeling is acknowledged as a scientifically sound alternative that maintains data integrity and has the potential to rescue BE studies at risk of failure.
Patient-Based BE Studies and Real-World Evidence
Healthy volunteers are typically the preferred subjects for BE studies; however, there is increasing acknowledgment that some products need testing in patient populations. As of May 2023, there are 57 Product-Specific Guidances (PSGs) advocating for PK- BE studies involving patients. Additionally, real-world evidence is becoming more significant, enhancing traditional BE studies.
Zenovel offers extensive bioequivalence study services to assist generic manufacturers through its global presence in key markets like India, the USA, Canada, and the EU. Our clinical trial services cover Phases I to IV, including tailored BE and PK studies. The PK-Stat review provides essential statistical support for regulatory submissions, focusing on study design, data management, and bioequivalence assessment. Zenovel specializes in complex generics, offering study design, execution, and regulatory strategy support. Our Risk-Based Monitoring (RBM) approach enhances safety and compliance while optimizing costs. The regulatory team has extensive experience in submissions for marketing authorization applications and uses eCTD software for EU and US regulations, leveraging global expertise combined with local insights.
Bioequivalence studies are critical for ensuring patients have timely access to affordable medications. Zenovel offers comprehensive services to assist with generic submissions related to bioequivalence. Contact us today at bd@zenovel.com
