Quantification of intraoperative administration of mitomycin-C in filtering surgery with surgical sponge material

Purpose: To determine the absorption and release of mitomycin-C 0.4 and 0.2 mg/mL from sponge-like specimens of Spongostan film (Ferrosan, Copenhagen, Denmark) and the scleral and conjunctival impregnation in an experimental model of filtering surgery. Methods: The maximum amount of mitomycin per volume unit that Spongostan is able to absorb was determined physically as the difference between dry wei ght and soaked weight. Mitomycin-C activity in known volumes of Spongostan after mitomycin-Cr release in vitro also was determined at 0, 1, 10, and 30 seconds and 1, 3, 5, 10, 15, and 30 minutes. Antibiotic activity of the sp ecimens was evaluated by means of bioassay, Millimeters of inhibition of ba cterial growth were related to mu g of mitomycin activity according to a re ference curve obtained from known amounts of mitomycin-C. Finally, 10 eyes of 10 rabbits underwent filtering surgery with intraoperative application o f mitomycin by means of the Spongostan film. The Spongostan implants then w ere removed and tested for mitomycin activity. Scleral and conjunctival spe cimens were obtained fur bioassay. Results: The maximum capacity of 25 mm(2) x 0.5 mm thick Spongostan films s aturated in 0.4 and 0.2 mg/mL solutions of mitomycin-C were 8.49 mu g and 4 .23 mu g, respectively, Biologic activity (bioassay determination) was 8.24 mu g and 4.19 mu g of mitomycin-C, respectively. In vitro release of mitom ycin was gradual until 30 minutes. in viva mitomycin release from Spongosta n after 5 minutes was 6.91 mu g. Impregnation with the antimitotic was bett er in conjunctiva than sclera. Conclusion: Bioassay permits quantification of mitomycin-C activity. The re lease from sponge specimens is gradual, and impregnation was better in conj unctiva than sclera.