Surface Tensiometry Evaluation of Ex-Vivo Permeation Process of Active Substance Using Solid-Like Method

Davide Rossi, Elisa Vettorato and Nicola Realdon
Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy

Abstract

The Solid-like method (SLM) is capable to use a perfluoropoliether (PFPE) both as a solid substrate and a test liquid determining the contact angle between a liquid and the surface of a PFPE liquid film (PFPEf). The contact between liquid and PFPEf led to the formation of a meniscus without the application of external forces and the surface tension properties of the liquid. The dimension of the meniscus is called Rossi number (Rn) capable to characterize the deformation of the PFPEf. Our aim was the application of Rn on the permeation process of an active substance (a.s.) released from a test ointment across an ex vivo biological membrane. The quantitative analysis of a.s. was carried out by a HPLC apparatus equipped with an Evaporative Light Scattering detector. Rn was carried out by contact angle analysis of acceptor solutions collected from each of 5 Franz’s cells in 3÷12 hour range time. The results demonstrated the applicability of Rn on the analysis of the surface tension properties of liquid system because the high correlation degree between Rossi number and a.s. concentration in Franz cells A (R2=0.9967), B (R2=0.9794), C (R2=0.9671), D (R2=0.9678), and E (R2=0.9975). The analysis of the deformation of liquid film confirm the high capability of SLM to detect in non invasive and rapid way the variations of liquid systems in relation to the addition of a substance over the time. SLM also confirm to be a new tool for the characterization of the permeation process in pharmaceutical technological field.


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