A bioadhesive patch cervical drug delivery system for the administration of 5-fluorouracil to cervical tissue

Abstract A novel bioadhesive cervical patch drug delivery is described, containing 5-fluorouracil for the treatment of cervical intraepithelial neoplasia (CIN). The patch was of bilaminar design, with a drug-loaded bioadhesive film cast from a gel containing 2% (w/w) Carbopol® 981 plasticised with 1% (w/w) glycerin. The casting solvent was ethanol/water 30:70, chosen to give a non-fissuring film with an even particle size distribution. The film, which was mechanically stable on storage under ambient conditions, was bonded directly to a backing layer formed from thermally-cured polyvinyl chloride emulsion. Bioadhesive strength was independent of drug loading in the bioadhesive matrix over the range investigated but was influenced by both the plasticiser concentration in the casting gel and the thickness of the final film. Release of 5-fluorouracil from the bioadhesive layer into an aqueous sink was rapid but was controlled down to an undetectable level through the backing layer. The latter characteristic was desirable to prevent drug spill from the device onto vaginal epithelium in vivo. Despite the relatively hydrophilic nature of 5-fluorouracil, substantial drug release through human cervical tissue samples was observed over approximately 20 h. Drug release, which was clearly tissue rather than device dependent, may have been aided by a shunt diffusion route through aqueous pores in the tissue. The bioadhesive and drug release characteristics of the 5-fluorouracil cervical patch indicated that it would be suitable for further clinical investigation as a drug treatment for CIN.