[Pharmacokinetics of subconjunctivally injected drugs in the anterior segment of rabbit eyes].

We injected 12.5, 25, 50 and 100 microliters portions of a combined solution of 2.5% sodium fluorescein (FL), 2.5% cefmenoxim hemihydrochloride (CMX), and 0. 25% chloramphenicol (CP) subconjunctivally into rabbit eyes by various methods. Drug levels were monitored in the tears and aqueous humor and measured via high performance liquid chromatography. In the tear fluid, the concentrations of CP decreased more rapidly with time than FL and CMX. The drugs penetrated the rabbit's eyes better when injected subconjunctivally than when administered by sub-Tenon's injection. After subconjunctival injection through the eyelid, the drug concentration in the tears decreased with time in almost the same way as for injection through the conjunctival membrane. There was little difference between the presence and absence of a puncture hole in the conjunctiva. When the whole cornea was sealed with cyanoacrylate glue to block transcorneal absorption, the FL concentration in the aqueous humor was 30% of that in the control and the CP concentration was less than 10% of that in the control. About 70% of FL penetrating the eyes was derived from the transcorneal route but most of the CP was derived from the transcorneal route. FL in 1% or 0. 25% sodium hyarulonate (HA) and saline was injected subconjunctivally, and the concentrations of FL in the cornea and vitreous humor were measured. FL in 0.25% HA penetrated rabbit eyes better than that in 1% HA. These findings suggest that by dissolving the drug in an adequate concentration of HA solution, better penetration of drugs into the eye can be obtained.