EFFECT OF PARTICLE-SIZE ON OCULAR PERMEABILITY OF PREDNISOLONE ACETATE IN RABBITS

The ocular permeability of two sieved fractions of prednisolone acetat e with a mean particle size of < 5-mu-m and 5-10-mu-m was studied in r abbits. The results show that there was not significant difference bet ween the corneal uptake of the two fractions of prednisolone acetate. Prednisolone acetate was rapidly taken up by the cornea where it is hy drolyzed rapidly to prednisolone. Only prednisolone was detected in th e aqueous humor showing that prednisolone acetate is completely hydrol yzed in the cornea. Both fractions produced similar concentrations of prednisolone in the aqueous humor. For prednisolone acetate, the perme ability rate rather than the dissolution rate seems to be the rate-lim iting step for corneal transport.