Drug Product Performance: Bioavailability, Relative Bioavailability and Bioequivalence, 2nd Edition

Dear Colleagues,

The incomplete systemic absorption of drugs following extravascular administration is a common occurrence, influenced by various factors such as formulation issues, the physicochemical properties of the drug, affinity to carrier-mediated transport systems, and chemical and metabolic stability. In the first volume of our Special Issue on "Drug Product Performance: Bioavailability, Relative Bioavailability and Bioequivalence", we concentrated on novel tools and methodologies for determining systemic bioavailability (BA), defined as the rate and extent to which a drug is absorbed from a pharmaceutical form and becomes available at the site of action, and bioequivalence (BE), defined as a sufficient similarity in bioavailability between two drug products, allowing for the assumption to be made that both products will present the same efficacy and safety (https://www.mdpi.com/journal/pharmaceutics/special_issues/GCW09W3EF7).

Understanding the extent of absorption in BA studies is crucial for determining the appropriate extravascular dosage. Similarly, achieving a similar rate and extent of absorption in BE testing facilitates the extrapolation of therapeutic outcomes between different pharmaceutical drug products. While these characteristics are traditionally evaluated through in vivo studies, the increasing complexity of new drug molecules and formulation technologies has prompted the pharmaceutical industry and regulatory agencies to seek alternative approaches. These approaches may either enhance study designs or even lead to study waivers for BA and BE assessments. This is exemplified by the recent openness to consider the necessity of conducting oral fed and proton-pump inhibitor interaction studies when developing immediate-release solid oral generic drug products by taking into consideration a comprehensive analysis of formulation differences, excipients, molecular properties, in vitro behavior, and physiological-induced changes.

In this second volume of our Special Issue on Drug Product Performance, we will continue to explore new tools and methodologies for establishing systemic bioavailability and bioequivalence. This includes in silico, in vitro, and in vivo methods. While various approaches will be accepted, we particularly encourage submissions of works utilizing integrative methodologies such a physiologically-based biopharmaceutical models (PBBM). We invite researchers, drug developers, and regulators to contribute original research or review articles offering expert opinions and perspectives in this field.

Dr. Paulo Paixão
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• bioavailability
• relative bioavailability
• bioequivalence
• biowaivers
• statistical issues
• regulatory issues
• in vitro–in vivo correlations
• physiologically-based biopharmaceutical models
• physiologically-based pharmacokinetic models
• qualification of models
• population pharmacokinetic models
• biopharmaceutical classification system
• in vitro dissolution
• dissolution metrics
• predictive dissolution
• clinical trial simulations
• clinical trial optimization
• healthy subjects in BA/BE trials
• patients in BA/BE trials
• pharmacokinetic parameters for BA/BE assessment
• narrow therapeutic index drugs
• highly variable drug products
• immediate-release formulations
• modified-release formulations
• multiphasic drug products
• extravascular routes of administration