Intermittent vs continuous steroid administration. Efficacy in experimental conjunctivitis

The development of techniques for the continuous administration of drugs to the eye raises the question of whether a conjunctivitis can be controlled by continuous low rates of steroid release, or whether large, intermittent doses of steroid, as provided by eyedrops, are necessary. Efficacy of the two modes of drug administration was evaluated in a conjunctivitis model produced in immunized rabbits by daily topical ocular challenge with antigen. The acetates of hydrocortisone and prednisolone were released from a drug delivery system inserted in the cul-de-sac of the eye or were provided in eyedrops. The model was sufficiently sensitive to differentiate between the effectiveness of hydrocortisone and prednisolone. The continuous delivery of either steroid from the drug delivery system was as efficacious, or more so, than the corresponding steroid dose given as eyedrops.