Autoradiographic imaging of the distribution of 5-fluorouracil through cervical tissue following in vitro surface application of a bioadhesive cervical patch.

The distribution of 5-fluorouracil through cervical tissue has been assessed following the in vitro application of a bioadhesive patch to excised human cervix. The bioadhesive matrix contained a total of 20 mg of 5-fluorouracil spiked with 5-fluorouracil-6-3H and was applied for fixed periods of either 4 or 24 hours. Tissue slices were sectioned perpendicular to the plane of the applied patch and the autoradiographic image developed by placing a frozen tissue slice on Hyperfilm with subsequent instant thawing and refreezing, the resulting bilayer being maintained at -18 degrees C for 24 hours. The developed image was analysed by scanning densitometry and raster scans were visualised with three-dimensional contouring software. The autoradiograms showed darker areas surrounding tissue ducts, suggesting that 5-FU was spilling from the lumen into the surrounding stroma. Transport of 5FU via aqueous channels may thus make an important contribution to the rapid penetration of the drug through the cervical stroma. Three-dimensional autoradiographic images showed that, for a 4-hour patch application, there were areas of relatively low drug concentration within the upper 5 mm of tissue, where CIN lesions can exist in the glandular tissue or cervical crypts. However, extending the application time to 24 hours produced areas of high drug concentration extending throughout this region.