Lucy Zhao, manager of the Skin Lab at CPL has over 15 years of experience in GMP laboratories with extensive experience in development and validation for IVRT and IVPT testing. Lucy has assisted numerous clients in various stages of their topical product, including generic product development, scale-up process and achieving successful FDA post–approval changes and ANDA bioequivalent submissions.
 
Contract Pharma: Can you tell us what IVRT testing is?

Lucy Zhao: IVRT stands for in-vitro Release Testing. It measures the release rate and cumulative amount of an active pharmaceutical ingredient (API) from a topical dosage form into a suitable medium under specific experimental conditions.   
CP: How is IVRT used in generic product development?
 
Zhao: First, IVRT can support scale-up development for generic drugs. Second, IVRT can optimize the generic topical drug formulation. By testing different formulation variables (such as excipients, particle size distribution or manufacturing processes), drug developers can identify the formulation that achieves the desired release profile, ensuring effective drug delivery and bioavailability. Third, IVRT can predict how a generic product will behave in-vivo based on its in-vitro release profile. This predictive tool can avoid expenditure of unnecessary resources in further development of unsuitable formulations.  
CP: What is the role of IVRT in FDA SUPAC-SS guidance?
 
Zhao: SUPAC-SS stands for non-sterile semi-solid product scale-up or post-approval changes. This guidance provides recommendations to pharmaceutical companies that intend to scale-up or scale-down manufacture, change the components or composition, change the manufacturing process or equipment, and change the site of manufacture of a semi-solid formulation, either an NDA or ANDA product, during the post-approval period. IVRT plays a key role in this guidance as it is often used to assure that product quality and performance are maintained in the presence of change. It is a useful test to assess product sameness between pre-change and post-change products.
 
CP: Why is IVRT testing important for ANDA submission?
 
Zhao: In the FDA/EMA guidelines, IVRT study combines with pivotal IVPT study to provide the bioequivalence assessment of generic product against its reference release drug. A Pivotal IVRT study includes five key study phases during ANDA submission process: Analytical Method Development, Analytical Method Validation, IVRT method development, IVRT method validation and Pivotal IVRT comparison. Pivotal IVRT study combines with Pivotal IVPT study to provide a bioequivalent assessment of generic product against Reference Listed Drug.
 
CP: What services does CPL Skin Lab offer?

Zhao: We offer a wide range of IVRT services, including the early to late stage of generic product development, analytical method development and validation, IVRT method development and validation, scale-up or other post-approval changes, pivotal IVRT studies for bioequivalence evaluation—all in compliance with FDA or EMA guidelines.  
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