sodium-pertechnetate-tc-99m and hydroxyethylcellulose

Studies of the rate of clearance of a gellan gum formulation (Gelrite) radiolabelled by the inclusion of technetium-99m labelled diethylenetriaminepentaacetic acid were carried out in volunteer subjects and in rabbits. Disposition was followed by gamma scintigraphy and compared with 0.5% w/v hydroxyethylcellulose (HEC) solution and isotonic saline administered to the same subjects. Clearance of all solutions was found to follow bi-exponential kinetics with differences in clearance rates between the two species studied. A significant retention of the gellan gum formulation compared to HEC (p = 0.006) or saline (p = 0.009) was noted in man, but not in the rabbit. In this latter species the HEC showed greater retention compared to Gelrite. The species-specific differences in the precorneal residence of the formulations are attributed to the different physiological responses following instillation of solutions into the eye.

Topics: Analysis of Variance; Animals; Cellulose; Cornea; Female; Humans; Image Processing, Computer-Assisted; Male; Ophthalmic Solutions; Polysaccharides, Bacterial; Rabbits; Radionuclide Imaging; Random Allocation; Sodium Chloride; Sodium Pertechnetate Tc 99m