Publications by authors named "Yu Chung Tsang"

This report summarizes relevant insights and discussions from a 2022 FDA public workshop titled Best Practices for Utilizing Modeling Approaches to Support Generic Product Development which illustrated how model-integrated evidence has been used and can be leveraged further to inform generic drug product development and regulatory decisions during the assessment of generic drug applications submitted to the FDA. The workshop attendees discussed that model-integrated evidence (MIE) approaches for generics are being applied in the space of long-acting injectable (LAI) products to develop shorter and more cost-effective alternative study designs for LAI products. Modeling and simulation approaches are utilized to support virtual BE assessments at the site of action for locally acting drug products and to assess the impact of food on BE assessments for oral dosage forms.

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On November 30, 2021, the US Food and Drug administration (FDA) and the Center for Research on Complex Generics (CRCG) hosted a virtual public workshop titled "Establishing the Suitability of Model-Integrated Evidence (MIE) to Demonstrate Bioequivalence for Long-Acting Injectable and Implantable (LAI) Drug Products." This workshop brought relevant parties from the industry, academia, and the FDA in the field of modeling and simulation to explore, identify, and recommend best practices on utilizing MIE for bioequivalence (BE) assessment of LAI products. This report summerized presentations and panel discussions for topics including challenges and opportunities in development and assessment of generic LAI products, current status of utilizing MIE, recent research progress of utilizing MIE in generic LAI products, alternative designs for BE studies of LAI products, and model validation/verification strategies associated with different types of MIE approaches.

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This report summarizes the proceedings for day 2 sessions 1 and 3 of the 2-day public workshop entitled "Regulatory Utility of Mechanistic Modeling to Support Alternative Bioequivalence Approaches," a jointly sponsored workshop by the US Food and Drug Administration (FDA) and the Center for Research on Complex Generics (CRCG). The aims of this workshop were: (1) to discuss how mechanistic modeling, including physiologically-based pharmacokinetic (PBPK) modeling and simulation, can support product development, and regulatory submissions; (2) to share the current state of mechanistic modeling for bioequivalence (BE) assessment through case studies; (3) to establish a consensus on best practices for using PBPK modeling for BE assessment to help drive further investment by the generic drug industry into mechanistic modeling and simulation; and (4) to introduce the concept of a Model Master File to improve model-sharing. The theme of day 2 covered PBPK absorption model for oral products as an alternative BE approach and a tool for supporting risk assessment and biowaiver (session 1), oral PBPK for evaluating the impact of food on BE (session 2), successful cases, and challenges for oral PBPK (session 3).

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Patients with sickle cell disease (SCD) who undergo repeated blood transfusions often develop iron overload. Deferiprone (Ferriprox®) is an oral iron chelator indicated for the treatment of transfusional iron overload due to thalassemia syndromes and has been recently approved as a treatment for iron overload in adult and pediatric patients with SCD and other anemias. The present study aims to characterize the pharmacokinetic (PK) profile of deferiprone (DFP) in adult subjects with SCD.

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Background: Transfusion-dependent haemoglobinopathies require lifelong iron chelation therapy with one of the three iron chelators (deferiprone, deferasirox, or deferoxamine). Deferasirox and deferiprone are the only two oral chelators used in adult patients with transfusion-dependent haemoglobinopathies. To our knowledge, there are no randomised clinical trials comparing deferiprone, a less expensive iron chelator, with deferasirox in paediatric patients.

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Article Synopsis
  • Bioequivalence (BE) is crucial for the development and approval of new and generic drugs, but regulations differ across countries, leading to potential duplication of studies.
  • * Harmonizing BE regulations can reduce unnecessary drug exposure in humans and streamline the approval process.
  • * The Global Bioequivalence Harmonization Initiative (GBHI) was launched by EUFEPS/BABP to foster international collaboration and dialogue among pharmaceutical scientists and regulatory bodies on BE issues.
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This study evaluated whether deferiprone, an oral iron chelator, acts to prolong the QT interval. Fifty healthy volunteers received single doses of each of the following: therapeutic dose of deferiprone (33 mg/kg), supratherapeutic dose (50 mg/kg), placebo, or moxifloxacin, a positive control known to significantly prolong QT interval. Following each dose, subjects underwent cardiac monitoring, pharmacokinetics assessments, and safety assessments.

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Aims: In light of the growing recognition of renal disease in thalassemia, it is important to understand the impact of renal impairment on the pharmacokinetics of iron chelators. This study evaluated the pharmacokinetics and safety of the iron chelator deferiprone (DFP) in subjects with renal impairment in comparison with healthy volunteers (HVs).

Methods: Thirty-two subjects were categorized into four groups based on degree of renal impairment: none, mild, moderate or severe, as determined by estimated glomerular filtration rate (eGFR).

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The Biopharmaceutics Classification System (BCS), based on aqueous solubility and intestinal permeability, has enjoyed wide use since 1995 as a mechanism for waiving in vivo bioavailability and bioequivalence studies. In 2000, the US-FDA was the first regulatory agency to publish guidance for industry describing how to meet criteria for requesting a waiver of in vivo bioavailability and bioequivalence studies for highly soluble, highly permeable (BCS Class I) drugs. Subsequently, the World Health Organization (WHO) and European Medicines Agency (EMA) published guidelines recommending how to obtain BCS biowaivers for BCS Class III drugs (high solubility, low permeability), in addition to Class I drugs.

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Regulatory approaches for evaluating therapeutic equivalence of multisource (or generic) drug products vary among different countries and/or regions. Harmonization of these approaches may decrease the number of in vivo bioequivalence studies and avoid unnecessary drug exposure to humans. Global harmonization for regulatory requirements may be promoted by a better understanding of factors underlying product performance and expectations from different regulatory authorities.

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Regulatory approaches for evaluating therapeutic equivalence of multisource (or generic) drug products vary among different countries and/or regions. Harmonization of these approaches may decrease the number of in vivo bioequivalence studies and avoid unnecessary drug exposure to humans. Global harmonization for regulatory requirements may be promoted by a better understanding of factors underlying product performance and expectations from different regulatory authorities.

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