Modification of the conformational skin structure by treatment with liposomal formulations and its correlation to the penetration depth of aciclovir

• Published in: European journal of pharmaceutics and biopharmaceutics Vol. 79; no. 1; pp. 76 - 81
• Main Authors: Hasanovic, Amra, Winkler, Regina, Resch, Guenter P., Valenta, Claudia
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2011
• Subjects: Abdomen - physiology; Aciclovir; Acyclovir - administration & dosage; Acyclovir - chemistry; Acyclovir - metabolism; Animals; Antiviral Agents - administration & dosage; Antiviral Agents - chemistry; Antiviral Agents - metabolism; Biocompatible Materials - analysis; Biocompatible Materials - chemistry; Biocompatible Materials - metabolism; Chitosan - analysis; Chitosan - chemistry; Chitosan - metabolism; Cryo-TEM; DPPC liposomes; Drug Compounding; Drug Delivery Systems; Drug Evaluation, Preclinical; Ear - physiology; Epidermis - metabolism; FTIR; Humans; Lipids - analysis; Lipids - chemistry; Liposomes - chemistry; Liposomes - metabolism; Permeability; Skin - chemistry; Skin - metabolism; Skin Absorption; Spectroscopy, Fourier Transform Infrared; Swine; Tape stripping; Water Loss, Insensible - physiology; Tape stripping; Aciclovir; DPPC liposomes; Cryo-TEM; FTIR
• ISSN: 0939-6411; 1873-3441
• DOI: 10.1016/j.ejpb.2011.01.018

Cryo TEM micrographs of DPPC and Chitosan-DPPC liposomes. The stratum corneum (SC), top layer of the epidermis, is comprised mostly of lipids that are responsible for the permeability properties of the SC and which protect the body from external agents. Changes in these skin microconstituents can be understood by instrumental methods such as attenuated total reflectance Fourier-transform infrared (ATR–FTIR) spectroscopy. The present work shows that different types of analyzed skin, dermatomed abdominal porcine skin, pig ear skin, and human heat separated skin, influenced both the shape and the intensity of recorded spectra. The typical FTIR spectral bands of the conformation of the lipid aliphatic chains in the skin samples were altered after treatment with pure DPPC liposomes and chitosan (CS) coated DPPC liposomes, but not with aqueous CS-solution. The conformational change could be the reason for the variable permeability of the skin. This was confirmed by tape stripping on pig ear skin (imitating in vivo studies): the amount of aciclovir penetrating from polymer coated and polymer free liposomes was significantly higher under the skin surface in comparison with the aqueous CS-solution. Moreover, the addition of the polymer to liposomes induced a higher skin penetration than pure liposomes. One explanation might be the CS’s stronger adhesion to the skin.