Ciclosporin concentration in the rabbit aqueous humor and cornea following subconjunctival administration. Importance of anatomical site of injection.

The model compound lidocaine was used in the rabbit to investigate different sites of subconjunctival injection for the achievement of reproducible drug concentrations in the aqueous humor. Only epibulbar injections were satisfactory, but not parabulbar or injections under the lower fornix. After epibulbar administration of 0.8 ml 5% ciclosporin, median concentrations in the aqueous humor were 360, 700 and 200 ng/ml after 2, 8, and 24 h, respectively. Corresponding levels in the cornea were 32, 27, and 12 ng/ml. It appears that drug concentrations resulting from epibulbar injections may be therapeutically useful.