Assessment oftheprecorneal residence ofan ophthalmic ointment inhealthy subjects

1 Theprecorneal residence ofan ophthalmic ointment radiolabelled byinclusion of technetium-99m tincolloid was assessed inseven volunteer subjects usingthe technique ofgamma scintigraphy andcompared with asolution of0.3 % w/vhydroxypropylmethylcellulose (HPMC)radiolabelled by inclusion oftechnetium-99m diethylenetriaminepentaacetic acid inthesame subjects. 2 Themean half-times (±s.d.) ofcorneal residence were6490 ± 5404 s(108 min)forthe ointment and13± 24sforthe0.3%w/vHPMC solution (P< 0.01). 3 Thearea-under-curve value (AUC(0,540 s)), which reflects thetotal residence timeof thepreparation on theocular surface, wascalculated foreachvehicle ineachsubject. Themean (±s.d.) AUC(0,540 s)value fortheointment was 42170 (±5032)% sand forthe0.3%w/vHPMC solution itwas 8394(±4641) % s(P< 0.01).