Practical insights into additional strength biowaivers for oral solid dosage forms: current requirements by major regulatory agencies and path towards harmonization

Additional strength biowaivers offer a strategic advantage in pharmaceutical development by enabling regulatory approval of multiple strengths without separate bioequivalence (BE) studies. This review provides a comprehensive and timely analysis of current regulatory expectations for such waivers across major jurisdictions-USFDA (USA), EMA (Europe), HC (Canada), and ANVISA (Brazil)-for both immediate-release (IR) and modified-release (MR) solid oral dosage forms. The review also explores the evolving harmonisation efforts under the ICH M13A and draft M13B guidelines, highlighting their potential to streamline global submissions and reduce development complexity.Key scientific criteria such as pharmacokinetic linearity, formulation proportionality, and dissolution similarity are critically examined, with emphasis on how agency-specific interpretations influence regulatory outcomes.Several hypothetical case examples are presented to illustrate how regulatory decisions vary based on product-specific nuances and regional requirements. These examples provide practical insights into navigating scenarios, such as deviations in formulation proportionality or dissolution variability, and demonstrate how alternative statistical approaches can support biowaiver eligibility.By bridging current practices with future harmonised standards, this review serves as a valuable and timely resource for pharmaceutical professionals. It empowers developers to align strategies with both existing and emerging guidelines, facilitating efficient, multi-market drug development and regulatory compliance.