Local toxicity of benzalkonium chloride in ophthalmic solutions following repeated applications.

We performed repeated toxicity studies of benzalkonium chloride (BAK)-containing vehicles of ophthalmic solutions in monkeys and rabbits to assess the local toxicity of BAK after repeated applications on the ocular surface. Local toxicity of BAK was evaluated by toxicity studies in which a 0.01% BAK-containing vehicle was applied twice/day for 52 weeks, 4 times/day for 39 weeks, or 6 times/day for 13 weeks, or in which a 0.005% BAK-containing vehicle was applied 6 times/day for 52 weeks or twice/day for 4 weeks in monkeys. Local toxicity of BAK was also evaluated where a 0.01% BAK-containing vehicle was applied 6 times/day for 6 weeks, or a 0.005% BAK-containing vehicle was applied twice/day for 39 weeks or 8 times/day for 4 weeks in rabbits. These doses were chosen because BAK is generally used at concentrations up to 0.01% in ophthalmic solutions. The BAK-containing vehicle did not cause ophthalmological changes suggestive of irritation, allergy, or corneal damage. We also did not observe any histopathological changes in the eyeball, eyelid, lacrimal gland, and nasal cavity, with repeated applications of BAK for up to 52 weeks, up to 8 times/day, or at concentrations up to 0.01%, in monkeys and rabbits. Our results suggest that BAK in concentrations up to 0.01% in ophthalmic solution is non-toxic to the eyeball, its accessory organs, and the nasal cavity after long repeated applications.

Ocular toxicity of benzalkonium chloride homologs compared with their mixtures.

This study was performed to assess the in vivo ocular toxicity of benzalkonium chloride (BAK) homologs compared with commercially available BAK (BAK mixture) and to assess the ocular toxicity of BAK homolog after repeated ocular application. Rabbit eyes were examined by ophthalmology and scanning electron microscopy (SEM) after 10 applications of BAK homologs with C12 (C12-BAK) and C14 (C14-BAK) alkyl chain lengths and a BAK mixture at concentrations of 0.001% (w/v), 0.003% (w/v), 0.005% (w/v), 0.01% (w/v) and 0.03% (w/v). The ocular toxicity of C12-BAK to rabbit eyes was examined by ophthalmology and histopathology after repeated ocular application for 39 weeks. In addition, the antimicrobial activities of C12-BAK and C14-BAK against A. niger, S. aureus and P. aeruginosa were assessed. Ocular toxicity of C12-BAK was less than those of the BAK mixture and C14-BAK. No ocular toxicity was noted after ocular application of 0.01% C12-BAK to rabbits for 39 weeks. C12-BAK showed antimicrobial activities at a concentration of 0.003%. These results suggest that the use of C12-BAK to replace BAK mixture as a preservative in ophthalmic solutions should be considered in order to reduce the incidence of the corneal epithelial cell injury induced clinically by BAK.

TNF-alpha is crucial for the development of autoimmune arthritis in IL-1 receptor antagonist-deficient mice.

IL-1 receptor antagonist-deficient (IL-1Ra(-/-)) mice spontaneously develop autoimmune arthritis. We demonstrate here that T cells are required for the induction of arthritis; T cell-deficient IL-1Ra(-/-) mice did not develop arthritis, and transfer of IL-1Ra(-/-) T cells induced arthritis in nu/nu mice. Development of arthritis was also markedly suppressed by TNF-alpha deficiency. We found that TNF-alpha induced OX40 expression on T cells and blocking the interaction between either CD40 and its ligand or OX40 and its ligand suppressed development of arthritis. These findings suggest that IL-1 receptor antagonist deficiency in T cells disrupts homeostasis of the immune system and that TNF-alpha plays an important role in activating T cells through induction of OX40.

Effects of substance P and IGF-1 in corneal epithelial barrier function and wound healing in a rat model of neurotrophic keratopathy.

PURPOSE: To establish a rat model of neurotrophic keratopathy and to examine the effects of the combination of substance P (SP) and insulin-like growth factor (IGF)-1 on corneal epithelial barrier function and wound healing in this model. METHODS: Corneal denervation was achieved by thermocoagulation of the ophthalmic branch of the trigeminal nerve. A modified Schirmer test was performed without topical anesthesia. Corneal epithelial barrier function was assessed by measurement of fluorescein permeability with an anterior fluorophotometer. Epithelial wound healing was evaluated by measurement of the area of the defect at various times after removal of the entire epithelium. Eye drops containing both 1 mM SP and IGF-1 (1 micro g/mL) were administered six times daily. RESULTS: The Schirmer test result in eyes subjected to trigeminal denervation was lower than that in control eyes. The fluorescein permeability of the corneal epithelium of denervated eyes was increased relative to that of control eyes. Furthermore, trigeminal denervation induced a delay in corneal epithelial wound healing. Application of eye drops containing SP and IGF-1 to denervated corneas restored the fluorescein permeability of the corneal epithelium to control levels and abolished the delay in epithelial wound healing. CONCLUSIONS: A rat model of neurotrophic keratopathy, characterized by reduced tear secretion, loss of corneal sensation, impaired epithelial barrier function, and delayed epithelial wound healing, was established by trigeminal denervation. Treatment with both SP and IGF-1 improved corneal epithelial barrier function and stimulated corneal epithelial wound healing in this model.

Differential effects between marimastat, a TNF-alpha converting enzyme inhibitor, and anti-TNF-alpha antibody on murine models for sepsis and arthritis.

We investigated the effects of marimastat, an inhibitor of TNF-alpha converting enzyme and matrix metalloproteinases, and anti-TNF-alpha antibodies on a murine model for sepsis, and on arthritis in human TNF-alpha transgenic mice. Marimastat (25-200 mg/kg) inhibited lipopolysaccharide (LPS)-induced soluble TNF-alpha production in mice in a dose-dependent manner. At an oral dose of 200 mg/kg, marimastat almost completely inhibited LPS-induced soluble TNF-alpha production, but only slightly delayed LPS lethality. On the other hand, anti-TNF-alpha antibodies completely abolished LPS-induced morbidity. In addition, anti-TNF-alpha antibodies, but not marimastat (200 mg/kg/day), inhibited the development of arthritis in human TNF-alpha transgenic mice. These results suggest that cell surface TNF-alpha may be important in the pathogenesis of murine models for sepsis and arthritis.