Use Ano Stability of Liposomes in Dermatological Preparations

In recent years liposomes have gained an increased interest as ingredients for topic formulations, both for their hydratating-humectant properties and as carriers for (trans)dermal delivery of active ingredients that exert their function at cutaneous and/or subcutaneous leve!. In this paper we describe (a) some aspects of liposome use with special regard their to stability in topica! formulations and (b) the modalities of skin-Jiposomes interactions after topica! application. A crucial aspect of the cosmetic utilisation of liposomes concerns indeed the intrinsic stability of the macromolecular structure of this vehicle, especially when liposomes are incorporated in surfactant containing forms as in the case of creams. In these conditions Iiposomes can be rapidly solubilized by a large variety of surfactants through a multi step process. With the aim to overcome this problem, the use of structured vehicles constituted of hydrophilic polymers has been recently proposed. With respect to this latest point, a number of mild formulations that could represent optimal vehicles for Iiposome incorporation is presented. Moreover we discuss the effect of the polymer used on the properties of structured vehicles (i.e. viscosity) and on the release of liposome entrapped model drugs.