FORMATION OF POROUS MEMBRANES FOR DRUG DELIVERY SYSTEMS

Highly crystalline porous hollow poly (L-lactide) (PLLA) fibres suitab le for the delivery of various drugs were obtained using a dry-wet spi nning process. The pore structure of the fibres could be regulated by changing the spinning systems and spinning conditions. Using the spinn ing system PLLA-dioxane-water, fibres with a dense toplayer and a spon gy sublayer were obtained. The spinning system PLLA-chloroform/toluene -methanol yielded fibres with a very open porous structure. The membra ne formation of the former system probably occurs by liquid-liquid dem ixing followed by crystallization of the polymer rich phase. In the me mbrane formation process of the spinning system, PLLA-chloroform/tolue ne-methanol crystallization probably plays a dominant role. The membra ne formation process will be related to basic principles of phase sepa ration. The fibres are suitable for the long term zero order delivery of the contraceptive 3-ketodesogestrel and the short term zero order d elivery of the cytostatic agent, cisplatin. The drugs are released by dissolution of the drug crystals in the fibre core followed by diffusi on through the membrane structure. Short term release of adriamycin co uld be obtained through an adsorption-desorption mechanism. The pore s tructures of the fibres have a large influence on the release rates of the drugs investigated. When fibres with dense toplayers were used. l ow release rates of drugs were observed whereas fibres with well inter connected pore structures over the fibre wall showed very high release rates.