Modelling drug delivery mechanisms for microencapsulated substances applied on textile substracts

Abstract

Mathematical drug release modelling of biodegradable polymeric systems by microencapsulation technology in textiles has not progressed much yet, because it is generally too complex. The release of a therapeutic agent from a formulation applied to the skin surface and its transport to the systemic circulation has a multistep process. The transdermal drug released is a feasible administration route for powerful, low-molecular weight therapeutic agents, which has to be accurate in their control of drug distribution. Moreover, many drugs are difficult to handle because they must be delivered slowly over a prolonged period to have a beneficial effect. In the present work, several examples of practical applications of mathematical models, developed through experimental drug release data, are given. For those involved in the design and development of biodegradable drug delivery systems, it will be useful to choose the generic mathematical model for several specific drug release problems. This transport model is based on the appropriate solution to Fick's second law of diffusion and can be used to explain drug release kinetics into this complex biological membrane (skin). Microspheres containing active principles were prepared using a solvent evaporation procedure with poly(vinyl alcohol) as surfactant in the external aqueous phase. Several biodegradable microspheres of biocompatible polymers, taken as delivery systems for active agent, have been studied. Polymers were PLGA (Poly(lactide-co-glycolide)) and PCL (poly(e-caprolactone)). The active compounds chosen were cosmetics and drugs, such as gallic acid, caffeine and ibuprofen. The microspheres obtained were characterized by the measure of encapsulation efficiency. The surface morphology and chemical structure of the micro particles were investigated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Nanosizer was used for particle size distribution. The application of the microspheres in the fabrics was carried out using Pad-Dry technique, since it is a simple and efficient technology and its working conditions are harmless to the system. The drug release system was analyzed, through samples of the treated fibre (cotton, polyamide, acrylic and polyester) in order to study the drug delivery behaviour in different media, deionized water and physiological saline (T=37ºC). The skin penetration profile by in vitro technique for different active principles was determined using pigskin. The release experiments are performed resorting to the Franz Diffusion cells apparatus (Lara-Spiral, Courtenon, France) consisting of two thermostatic chambers, the upper donor and the lower receptor chamber, divided by a skin biopsy. The main objective of this study is to create smart textiles which allow a controlled drug release for any active compound/substance. Such objective will allow the control of the textiles drug release in such a way that the active compound is released in the right quantity, at the right time and at the right place. The present study has shown that the main objective has been successfully achieved. According to that, microencapsulation applied on fabrics can be considered as a good controlled release system. As a result, the project reached to a general kinetic model using smart textiles as a mass transport system through the skin.