Iontophoresis of 5-fluorouracil into the conjunctiva and sclera

It was investigated in the rabbit eye whether the method of iontophoresis could introduce a sufficient amount of 5-fluorouracil (5-FU) to inhibit fibroblast proliferation into the conjunctiva and sclera, thus considerably reducing the total amount of 5-FU which must be given to the eye. Five-FU was introduced with a simple apparatus which was filled with 5% 5-FU solution and connected to the negative pole of a current source. When the apparatus was placed over the cornea, the 5-FU penetration into the cornea showed a correlation with strength of current (0-0.75 mA). When the apparatus was placed over the bulbar conjunctiva, a sufficient amount of 5-FU to inhibit fibroblast proliferation was introduced into the conjunctiva and sclera with a current of 0.5 mA passed for 30 seconds. Immediately after iontophoresis, mean 5-FU concentrations in the conjunctiva and sclera at the iontophoresis site were 480 and 168 micrograms/g, respectively. They decreased to 0.6 and 1.2 micrograms/g by 10 hr, but were still above the reported ID50 levels for the cultured conjunctival fibroblast. On the other hand, the total amount of 5-FU introduced into the eye averaged only 3.7 micrograms and the current used was much lower than that formerly applied to the patient's cornea.