Capacity and tolerance of a new device for ocular drug delivery.

A new method to increase the drug-capacity of the OphthaCoil, a flexible and tubular device for delivery of drugs to the tear film of the eye, was explored. Poly(2-hydroxyethyl methacrylate)- and poly(2-hydroxyethyl methacrylate-co-1-vinyl-2-pyrrolidone)-microspheres were prepared by suspension polymerization. The resultant particles were swollen in a highly concentrated solution of either the dye fluorescein sodium or the antibiotic chloramphenicol. The loaded particles were placed in the central cavity of the ocular device. In vitro release profiles showed a six-fold increase of the capacity for the dye fluorescein sodium, but not for the antibiotic chloramphenicol. Flexibility measurements revealed that by introducing microspheres in the central cavity of the device, flexibility did not decrease. Finally, a preliminary in vivo evaluation of the device (n=5) was done for a 2h-period to assess the tolerance of the device in the human eye. Ophthalmologic examinations and photographs of the eye indicated no signs of irritation. Volunteers reported that the presence of the device in the eye could be noticed, but no irritation was reported.