Concentrations of tritiated methotrexate in ocular compartments, serum and urine after subconjunctival and intravenous injection.

Forty-eight rabbits were given 6.25 mg/kg of tritiated methotrexate subconjunctivally or intravenously. Concentrations of the drug in ocular compartments, the serum and the urine were measured 0.5, 1, 2, 4, 8, 12, 24 and 48 hours after injection. Compared with intravenous administration subconjunctival injection resulted in 4.5 times more methotrexate in the anterior chamber, but the concentrations in the vitreous were the same with the two routes of administration. The serum levels of methotrexate, however, were nine times lower after subconjunctival injection.