Water-soluble methochloride of RU 486 fails to reduce intraocular pressure in normal rabbits

RU 486 is a new water-insoluble drug which blocks peripheral glucocorticoid and progesterone receptors. As eye drops and by subconjunctival injection, it has been shown to lower normal rabbit intraocular pressure by a small amount. To try to improve the intraocular penetration, a water-soluble methochloride was prepared. In a series of 11 rabbits (initially 12: 1 died) treated in one eye at random with a 1% solution of the methochloride of RU 486 (vehicle drops to the fellow eye) no effect on intraocular pressure was found. The ionic nature of the methochloride may have prevented the drug becoming attached to, and blocking, the postulated glucocorticoid receptors in the rabbit outflow channels, although it may have penetrated the cornea more effectively.