A soluble sustained-release ophthalmic delivery unit.

Four studies carried out in normal volunteers assessed the characteristics and acceptability of the matrix of a soluble sustained-release delivery system. Fourteen volunteers in the first study received crossover single applications of a rod- and oval-shaped soluble unit at 8 AM. Fifteen normal volunteers in the second study received soluble units at 9 PM in the inferior cul-de-sac. During the crossover phase, the units were placed into the superior cul-de-sac rather than the inferior cul-de-sac. In the third study, 15 normal volunteers received a rod-shaped unit in one eye and an oval-shaped insert in the opposite eye nightly for five successive nights. In Study 4, 24 normal volunteers subdivided into four groups of 12 eyes received an 18-mg rod, 24-mg rod, 18 mg-oval, or 24-mg oval unit at 9 PM. We concluded that the disappearance rate of these soluble units from the conjunctival sac depended on the size rather than shape and was not influenced by sleep. The soluble units were well tolerated.