Comparative Ocular Histopathological Effects of Eye Drops Containing Purite(R) (Oxychloro Complex) or Benzalkonium Chloride Preservatives in Rabbits

Abstract

Abstract: : Purpose: New, non-irritating preservatives are especially needed for ophthalmic products when the treatment is chronic or when the ocular surface is compromised as in dry eye. The microscopic ocular effects of repeat dosing with eye drops containing a conventional preservative, benzalkonium chloride (BAK), or a new preservative, Purite^(R) (stabilized oxychloro complex), were compared. Methods: New Zealand white rabbits (3/group) received in the left eye, 2 drops (6 times/day for 7 days) of 150, 250, or 500 ppm Purite^(R) in 0.5% carboxymethylcellulose (CMC), 150 ppm Purite^(R) in phosphate buffer, or 100 ppm BAK in phosphate buffer. The right eye served as the untreated control. The parameters evaluated were ocular discomfort, gross ocular observations, slit lamp biomicroscopy, and ocular histopathology. Results: Treatment with 100 ppm BAK in phosphate buffer caused transient minimal ocular discomfort (43% frequency). The frequency of minimal ocular discomfort in the Purite^(R) groups was 0 - 5% (p<0.001 in comparison with BAK group). Treatment with BAK caused transient mild ocular hyperemia (14% frequency), whereas no hyperemia noted in the Purite^(R) treatment groups. Treatment with BAK caused minimal to mild degeneration of the corneal epithelium and minimal to mild goblet cell loss in the conjunctiva (100% incidence). By contrast, for all Purite^(R) treatment groups combined, the only histopathological lesion was minimal goblet cell loss (8% incidence, p<0.001). Conclusions: Eye drops containing Purite^(R) were better tolerated than those containing BAK as measured by ocular response and histology in the rabbit. Purite^(R) provides a non-irritating preservative that may be especially useful for ophthalmic products used chronically or with a compromised ocular surface.

Keywords: cornea: epithelium • conjunctiva • pathology: experimental