Pharmacokinetics and metabolism of 5-fluorouracil following subconjunctival versus intravenous administration.

Two groups of six rabbits each were given 6.25 mg/kg of 6-carbon-14-labelled 5-fluorouracil (5-FU) either subconjunctivally or intravenously. The levels of the drug in the serum, the urine and the ocular humours 0.5, 1, 2, 4, 8 and 12 hours later were measured by high-pressure liquid chromatography, which distinguished between 5-FU and its metabolites. The peak levels of the parent drug in the serum and the urine were similar with the two routes of administration; however, compared with intravenous injection, subconjunctival injection resulted in 125 and 380 times the peak concentration of 5-FU in the anterior chamber aqueous and the vitreous respectively.