Scintigraphic assessment of the precorneal residence of a new ophthalmic delivery system (NODS) in man

Abstract The release of 99m Tc-labeled sodium pertechnetate and sulphur colloid from polyvinyl alcohol films for ophthalmic administration (new ophthalmic delivery system — NODS) has been studied in vitro and in vivo. 99m Tc-labeled sulphur colloid was selected as the marker for incorporation into the device to monitor dissolution on the cornea by gamma scintigraphy, in both rabbit and man. Clearance of the device followed mono-exponential kinetics with a mean half-time (±SD) of precorneal residence in man of 9.2 ± 7.4 min, demonstrating the potential of the formulation for sustained drug delivery.