Monolithic tetracycline-containing fibers for controlled delivery to periodontal pockets

For the purpose of developing controlled delivery devices for periodontal therapy which would release over several days, six fiber types made of tetracycline-loaded biocompatible polymers were manufactured and tested. Polyethylene, polypropylene, polycaprolactone, polyurethane and cellulose acetate propionate all released their drug load within 1 day. Ethylene vinyl acetate fibers, however, provided in vitro sustained release for periods up to 9 days. A bioassay was designed to measure levels of tetracycline achieved by local delivery which used growth inhibition of Bacillus cereus as a measure of the amount of tetracycline in measured volumes of gingival sulcus fluid on filter paper strips. By this assay, fibers made from 25% loaded ethylene vinyl acetate established initial concentrations of approximately 500 micrograms/ml. The measurement of tetracycline concentration resulting from the placement of these fibers into deep periodontal pockets as a packing material provided indication that concentrations of greater than 50 micrograms/ml could be maintained for months by weekly to monthly replacement. These studies indicate that monolithic fibers made of tetracycline-loaded ethylene vinyl acetate have characteristics which could prove useful as the basis of a tetracycline delivery system for the treatment of periodontal disease.