Bioavailability and Bioequivalence Assessment of Topical Drug Products Intended for Local Action

Dear Colleagues,

We are pleased to invite you to submit manuscripts for publication in a Special Issue of Pharmaceutics, entitled “Bioavailability and Bioequivalence Assessment of Topical Drug Products Intended for Local Action”. The market approval of a generic product requires the demonstration of bioequivalence (BE) against an innovator reference product in order to ensure safety and efficacy. Unlike extravascular dosage forms where well-established methods and regulatory guidelines are available for BE assessment, procedures or guidelines for the BE of topical dosage forms intended for local action, apart from the US FDA’s vasoconstrictor assay (VCA), are conspicuously absent. Most regulatory authorities usually require lengthy and expensive comparative clinical endpoint studies in patients. More recently, considerable efforts have been directed towards the development and validation of surrogate models to demonstrate the BE of topical products for local action and to facilitate the faster entry of generic products into the market. Requirements ensuring that such topical generic products are designed to match an approved reference product have been set out by regulatory authorities, where emphasis has been placed on specific quality properties such as qualitative (Q1), quantitative (Q2), and, particularly for semi-solid formulations, similarity in formulation microstructure (Q3). Currently, relatively few surrogate approaches to the assessment of the BE of topical dosage forms for local action have been explored. The more prominent methods include the vasoconstrictor assay (VCA), tape stripping, dermal microdialysis, open flow microperfusion and, more recently, the acceptance of biowaivers using in vitro release and permeation tests. In the latter instance, the US FDA has issued product-specific guidelines (PSGs) for topical products. In addition, the FDA published draft guidances in October 2022 on IVRT and IVPT studies, as well as on the physicochemical and structural (Q3) characterization of topical drug products submitted in ANDAs.

This Special Issue on the bioavailability (BA) and bioequivalence (BE) of topical formulations intended for local action will focus on research and review papers discussing applications of validated methods used to assess the BE of topical dosage forms not intended for absorption (i.e., excluding transdermal dosage forms) and will include both in vivo and in vitro methods.

We welcome articles dealing with all aspects of the BA/BE of topical dosage forms for local action, and invite researchers and drug developers to submit their original research or review articles with expert opinions and perspectives in this area.

Prof. Dr. Isadore Kanfer
Dr. Seeprarani Rath
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pharmaceutics is an international peer-reviewed open access monthly journal published by MDPI.

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.

• bioequivalence
• bioavailability
• biowaivers
• topical dosage forms for local action
• topical corticosteroids
• dermatopharmacokinetics
• in vitro release tests (IVRTs)/in vitro permeation tests (IVPTs)
• pharmaceutical equivalence
• semi-solid dosage forms
• human skin
• vasoconstrictor assay (VCA) in place of human skin