[In vitro diffusion of 5-fluorourcil and tegafur through excized pig cornea]

Permeability kinetics of 5-fluorouracil (5-FU), tegafur (TGF) and ftorafur (FT) through synthetic, lipophilic membranes and the pig excised cornea were studied. During the dialysis process, the drugs were dissolved in Ringer's solutions of either pH 6.89 or 7.98 and the drug concentrations were measured vs time by UV spectrophotometry at 37 degrees C. The diffusion processes of 5-FU, TGF and FT through the synthetic membranes were pH dependent and could be interpreted according to pseudo-first-order kinetics. However, the drug diffusion through the pig excised cornea was a zero-order process. The permeability rate of FT (TGF) across the pig cornea was greater if compared to that of 5-FU, whose partition coefficient (ko/w) was higher than those of the former drugs.