Ocular tolerance in rabbits after intracameral administration of a fixed combination of tropicamide, phenylephrine, and lidocaine with and without rinsing.

PURPOSE: To evaluate the safety and tolerability of a single intracameral administration of a combined mydriatic (tropicamide and phenylephrine) and anesthetic (lidocaine) formulation (Mydrane) with or without rinsing. SETTING: Iris Pharma, La Gaude, France. DESIGN: Experimental study. METHODS: Sixty pigmented rabbits received 100 µL or 200 µL of the combination product or a placebo (sodium chloride 0.9%) by intracameral injection. For the combination product, separate groups were included with and without rinsing after administration. From day 1 day to day 7, assessments included general clinical and ocular observations, pupil diameter measurements, corneal assessments, confocal microscopy, and electroretinography (ERG). Necropsy examinations were performed at study completion at day 8. RESULTS: Rapid mydriasis, stable 24 minutes after injection and returning to baseline levels by day 1, was induced in all groups that received the combination mydriatic and anesthetic drug. Rinsing had no effect. The combination product induced no adverse effects on the anterior or posterior segment of the eye (ie, no increased corneal thickness and endothelial cell loss, no abnormalities in ERG). Slitlamp examination showed slightly increased anterior chamber inflammation with rinsing in both the study group and placebo group. This observation was not confirmed by aqueous flare examination. No toxic effects of the products were found on histological evaluation. CONCLUSION: The combination mydriatic and anesthetic drug administered to pigmented rabbits as a single intracameral injection at volumes of 100 µL and 200 µL was well tolerated with no ocular adverse effects and no effect on the corneal endothelium.

Norbixin Protects Retinal Pigmented Epithelium Cells and Photoreceptors against A2E-Mediated Phototoxicity In Vitro and In Vivo.

The accumulation of N-retinylidene-N-retinylethanolamine (A2E, a toxic by-product of the visual pigment cycle) in the retinal pigment epithelium (RPE) is a major cause of visual impairment in the elderly. Photooxidation of A2E results in retinal pigment epithelium degeneration followed by that of associated photoreceptors. Present treatments rely on nutrient supplementation with antioxidants. 9'-cis-Norbixin (a natural diapocarotenoid, 97% purity) was prepared from Bixa orellana seeds. It was first evaluated in primary cultures of porcine retinal pigment epithelium cells challenged with A2E and illuminated with blue light, and it provided an improved photo-protection as compared with lutein or zeaxanthin. In Abca4-/- Rdh8-/- mice (a model of dry AMD), intravitreally-injected norbixin maintained the electroretinogram and protected photoreceptors against light damage. In a standard rat blue-light model of photodamage, norbixin was at least equally as active as phenyl-N-tert-butylnitrone, a free radical spin-trap. Chronic experiments performed with Abca4-/- Rdh8-/- mice treated orally for 3 months with norbixin showed a reduced A2E accumulation in the retina. Norbixin appears promising for developing an oral treatment of macular degeneration. A drug candidate (BIO201) with 9'-cis-norbixin as the active principle ingredient is under development, and its potential will be assessed in a forthcoming clinical trial.

Comparison of the Anti-Inflammatory Effects of Artificial Tears in a Rat Model of Corneal Scraping.

PURPOSE: Artificial tears (ATs) are used routinely to alleviate the symptoms of mild to moderate dry eye. Preservative-free cationic emulsions (eg, Cationorm(®)) are an innovative approach for the management of signs and symptoms of dry eye. The aim of the present exploratory experiment was to evaluate the efficacy of this cetalkonium chloride (CKC)-containing cationic emulsion on debrided cornea and to characterize its effects on scraping-induced inflammation. METHODS: Four ATs were assessed in a rat model of corneal scraping. The upper part of the corneal epithelium was scraped before a 5-day treatment, followed by clinical evaluations and fluorescein staining to evaluate cornea recovery. The anti-inflammatory efficacy of the ATs was assessed in vivo and in vitro. RESULTS: In vivo confocal microscopy (IVCM) revealed a trend toward better corneal clinical signs (lower IVCM scores) for the animals treated with the unpreserved ATs. Benzalkonium chloride treatment decreased goblet cell count by 37.5%. While the soft-preserved Systane Balance(®) and Optive(®) and the preservative-free Vismed(®) had no effect on the goblet cell count, Cationorm increased this count by almost 40%. Interestingly, inflammatory cell infiltration in the stroma was at its lowest following treatment with the preservative-free Cationorm. Cationorm is also the only AT decreasing IL6- and IL8-stimulated secretion by 59% and 74%, respectively. CONCLUSION: By restoring an adequately hydrated ocular surface environment, the different ATs promote corneal epithelium healing. These data position Cationorm as a promising AT for the management of signs and symptoms of dry eye in patients with mild to moderate dry eye disease presenting chronic subclinical levels of ocular inflammation.

Designing dendrimers for ocular drug delivery.

New series of phosphorus-containing dendrimers, having one quaternary ammonium salt as core and carboxylic acid terminal groups have been synthesized from generation 0 (3 carboxylic acid terminal groups) to generation 2 (12 carboxylic acid terminal groups). These dendrimers react with the neutral form of carteolol (an ocular anti-hypertensive drug used to treat glaucoma) to afford ion pair (saline) species. The solubility in water of these charged dendrimers depends on the generation considered: generation 0 (3 carteolol) is well soluble, whereas generation 1 (6 carteolol) and generation 2 (12 carteolol) are poorly soluble. These dendrimers have been tested in vivo, as vehicle for ocular drug delivery of carteolol to rabbits.

Ocular pharmacokinetic study following single and multiple azithromycin administrations in pigmented rabbits.

PURPOSE: The aim of this study was to investigate whether the ocular pharmacokinetic parameters observed following systemic administration are also seen following topical administration. METHODS: Azithromycin concentrations were measured by HPLC-MS in pigmented rabbits' tears, cornea, bulbar conjunctiva, and aqueous humor following single instillation and twice-daily instillations for three consecutive days of topical 1.50% azithromycin dihydrate solution. RESULTS: Following a single administration, azithromycin levels were higher than the MIC 4 microg/g breakpoint for susceptible germs for at least 4 hr in tears, 1 hr in conjunctiva, and 1 hr in cornea after instillation. Following multiple administrations, azithromycin levels were higher than the MIC 4 microg/g for at least 16 hr in tears, 24 hr in conjunctivae, and 1 week in cornea after the last instillation. CONCLUSIONS: Both dosage regimens resulted in adequate and long-lasting azithromycin levels in the conjunctiva, the ocular target tissue relative to the expected therapeutic indication in man (bacterial conjunctivitis), and also in the cornea and tears.

A new method for Intra Ocular Pressure in vivo measurement: first clinical trials.

Glaucoma is an ocular disease clinically manifested by an abnormal rise of the Intra Ocular Pressure (IOP) that causes lesions of the optic nerve and can lead to blindness. Ophthalmologists currently use applanation tonometers whose utilization induces multiple constraints. We propose an investigative method being at one and the same time atraumatic and ambulatory. This original device, taking profit of a physical relation between frequency of mechanical vibration of the ocular globe and IOP, involves vibrometry by laser interferometry and spectral analysis of a mechanical impulse using a temporal micro hammer. The laser energy delivered to the eye by the device was confirmed to be safe and in full agreement with the authorized security norms. After preliminary in vitro experiments performed using enucleated animal eyes, we made a clinical study on 25 volunteers to evaluate the innocuity and the reliability of this device and to quantify the reproducibility of measurements. All patients declared that discomfort is comparable with that felt during similar tests. Reliability is good and the intra individual reproducibility reveals a high value (R > or = 0.93). These works will be carried on to check the correlation between the variation of measured values (resonance frequency of the eye-ball) and the variation of reference (IOP) values.

In vivo and in vitro neurotoxicity of the human prion protein (PrP) fragment P118-135 independently of PrP expression.

We recently demonstrated that the 118-135 putative transmembrane domain of prion protein (PrP) exhibited membrane fusogenic properties and induced apoptotic neuronal cell death of rat cortical neurons, independently of its aggregation state. The aim of the present study was to analyze the in vivo neurotoxicity of the prion fragment P118-135 and to evaluate the potential role of the physiological isoform of PrP in the P118-135-induced cell death. Here, we demonstrate that the nonfibrillar P118-135 is cytotoxic to retinal neurons in vivo as monitored by intravitreal inoculation and recording of the electrical activity of retina and tissue examination. Moreover, knock-out PrP gene mice exhibit similar sensitivity to the nonfibrillar P118-135-induced cell death and electrical perturbations, strongly suggesting that cell death occurs independently of PrP expression. Interestingly, a variant nonfusogenic P118-135 peptide (termed P118-135theta) had no effects on in vivo neuronal viability, suggesting that the P118-135-induced cell death is mediated by its membrane destabilizing properties. These data have further been confirmed in vitro. We show that the fusogenic peptide P118-135 induces death of cultured neurons from both wild-type and knock-out PrP gene mice via an apoptotic-mediated pathway, involving early caspase activation and DNA fragmentation. Altogether these results emphasize the neurotoxicity of the fusogenic nonfibrillar PrP transmembrane domain and indicate that fibril formation and PrP expression are not obligatory requirements for neuronal cell death. The use of synthetic prion peptides could provide insights into the understanding of neuronal loss mechanisms that take place during the development of the various types of spongiform encephalopathies.

Timolol 0.1% gel (Nyogel 0.1% once daily versus conventional timolol 0.5% solution twice daily: a comparison of efficacy and safety.

In a prospective, randomised, double-masked, parallel-group, multi-centre study, 210 patients with primary open angle glaucoma or ocular hypertension were enrolled of whom 167 (timolol 0.1% gel 82, timolol 0.5% 85) completed the study as per protocol. The change in intraocular pressure between baseline and week 12 in the worse eye ('at trough') was 6.3 (SD 3.3) mm Hg on timolol 0.1% gel and 7.0 (2.9) mm Hg on timolol 0.5%; this difference was not statistically significant (p = 0.19). The difference between the two study groups in the change of intraocular pressure from baseline was 0.62 mm Hg; the 90% CI of -0.09 to +1.33 mm Hg was within the pre-specified limits of -1.5 to +1.5 mm Hg demonstrating equivalence between timolol 0.1% gel and timolol 0.5%. The plasma levels of timolol (ng/ml) at 12 weeks in the timolol 0.1% gel group were significantly less than that with timolol 0.5% both before instillation (mean 0.057, SD 0.131 and mean 0.470, SD 0.519 respectively, p = 0.025) and after instillation (mean 0.552, SD 0.992 and mean 2.473, SD 1.780 respectively, p = 0.008). Both treatments were well tolerated with no statistically significant difference between the groups in the occurrence of ocular or systemic adverse events.