Purpose:
To evaluate the amount of Mitomycin C (MMC) absorbed and delivered in different materials used in glaucoma surgery.
Methods:
For this in vitro study three types of transport materials were used: a) Polyvinyl alcohol triangle sponges (TS, two sizes); b) Polyvinyl alcohol fluid wicks (EFW) and c) Gelatin absorbable sponges (GAS, Spongostan-cutanplast, two sizes). Seven sponge pieces for each transport material and size were prepared and assessed. Two transversal stripes 4 mm-wide each were cut at 6 mm (TS6) and 8 mm (TS8) from the apex of the TS, and each strip was divided in 3 equal pieces. Four by four mm pieces of EFW were cut and, finally, 3x3 mm (GAS3) and 5x5 mm (GAS5) pieces of GAS were obtained. A filter paper was placed on the plate of a precision scale (0.01 mg). The 7 sponge pieces of each group were weighted 3 consecutive times in dry state and another 3 times in wet state after being submerged for 15 seconds in a 0.2 mg/ml MMC solution. To calculate the amount of MMC delivered from the sponge to the filter, filters were weighted at the end of each sequence of measurements and the differences between dry and wet sponges were calculated. ANOVA and Schéffé test analysis was performed to compare group and size differences in the percentage of MMC delivered. Coefficient of variation was used to evaluate the variability of MMC absorbed and delivered by each sponge type.
Results:
Dry sponges weight per group (mg) was: 2.62±0.55 for TS 6mm; 3.04±0.78 for TS 8mm; 1.68±0.14 for EFW; 0.90±0.31 for GAS 3x3, and 1.47±0.12 for GAS 5x5. The amount of MMC absorbed and delivered were as shown in the table. No statistical differences were found in the percentage of MMC delivered between sponges, but differences were found in the amount of MMC delivered.
*,+,&,$,#: p<0.05 between groups.
Conclusions:
Percentage of MMC delivered was similar for all materials but total MMC delivered is greater in larger sponges. Gelatin absorbable sponges of 5 mm seemed to deliver the most homogeneous amount of MMC.
Keywords: drug toxicity/drug effects