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FAQ – Can I skip IVRT and IVPT trials?


The skin is the largest organ of the human body and the primary barrier between the body and the external environment.  Due to its direct exposure, the skin is susceptible to various influences such as the external environment, internal diseases, and genetic factors. it is susceptible to a wide range of dermatological conditions due to its direct interaction with these influences.

In vitro release testing (IVRT) and in vitro permeation testing (IVPT) are key pharmaceutical techniques for evaluating the pharmaceutical research of topical dermatological formulations.  These tests can help researchers understand the drug’s release and permeation characteristics on the skin, providing critical insights for the drug formulation and preparation. Are you still confused about IVRT and IVPT?  Let’s listen together to Xiaolei Yu, the project manager of the Formulation Department at Medicilon, shares the experience with us.

Pharmaceutical preparation

Medicilon's Preparation Department is committed to providing clients with one-stop and systematic preparation development service, and can undertake the whole process of preparation R&D innovation from project evaluation and approval, preparation process research, quality standard establishment and research, clinical sample production, application and filing, etc.

Q: At which stage of the research process should IVRT and IVPT be initiated?

Xiaolei Yu: In the development process of both new drugs and generic drugs, based on past experience, It is recommended to initiate In Vitro Release (IVRT) studies during the early stage of prescription screening. IVPT would typically follow after confirming the prescription, ensuring that process scale-up and stability are satisfactory..  Certainly, IVPT experiments can also be conducted during the prescription screening stage, by examining the residual levels of the active substance within the skin to perform prescription screening.

Q: Is it mandatory to perform In Vivo Rate of Absorption (IVRT) and In Vivo Pharmacokinetics (IVPT) studies for a new drug?

Xiaolei Yu:  We have encountered numerous inquiries from clients regarding whether they can bypass IVRT and IVPT and proceed directly to efficacy studies, as long as the sample’s effectiveness. The client’s consideration is not wrong, as indeed the efficacy of the formulation is an important prerequisite for application submission.    However, we believe that research needs to have a certain logical integrity and scientific rigor. IVRT and IVPT, as part of in vitro evaluations, are indispensable, especially for the new drug submissions at the clinical trial stage. There needs to be a coherent progression in the research. The risk of directly focusing on efficacy is significant. It’s advisable to obtain results from in vitro experiments first before proceeding to in vivo trials. In this way, IVRT and IVPT can bridge pharmaceutical research with non-clinical and pharmacodynamic studies.  Therefore, I think these two experiments are necessary.

Q: Is IVPT necessary for damaged skin?

Xiaolei Yu:  Taking tacrolimus ointment as an example, which treats atopic dermatitis , where skin damage may occur. Therefore, when conducting in vitro evaluations of such formulations, In Vitro Release Testing (IVRT) and In Vitro Penetration Testing (IVPT) are indispensable guiding principles. Furthermore, IVPT is an in vitro evaluation method for topical formulations, and it is not significantly related to the indications of the product. Of course, we can choose evaluation methods that are more closely aligned with the indications based on specific administration routes.  For ocular formulations, during the evaluation process, we can use rabbit corneas instead of pig skin for assessment. Similarly, for vaginal formulations, we can use animal vaginal mucosa instead of skin for evaluation.  For rectal administration, we can use rectal mucosa for in vitro evaluation.  Medicilon has abundant animal resources, enabling us to internally coordinate to provide clients with more realistic in vitro assessment methods according to their needs.

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