The possible effect of topically applied azithromycin and moxifloxacin on the alleviation of uveitis

PURPOSE

To investigate the inhibitory effect of topically administered azithromycin (AZM), and moxifloxacin (MXF) against tumor necrosis factor-α (TNF-α) production in a rat model of endotoxin-induced uveitis (EIU).

METHODS

Thirty-six Wistar albino rats were divided into 6 equal groups. Groups 1, 2 and 3 were determined as sham, control group for topical AZM application and control group for topical MXF application, respectively. Sterile saline, topical AZM 1.5%, and topical MXF 0.5% were instilled 5 times daily for totally 6 days on both eyes of the rats in Group 4, Group 5, and Group 6, before and after inducing EIU by intravitreal injections of lipopolysaccharide, respectively. At 24 h after intravitreal injections, aqueous humor was collected from both eyes of each rat for the assessment of TNF-α concentration. Also, density of nuclear factor kappa B (NF-κB) in ciliary body, and the number of cells infiltrating the posterior segment of EIU rat eyes was assessed in one eye of each rat.

RESULTS

There was a significant reduction in mean aqueous humor concentration of TNF-α in EIU rats pretreated with topical AZM in comparison with those pretreated with sterile saline (139 ± 38.6 in Group 4 vs. 72 ± 12.6 in Group 5, p = 0.006). There was also a marked decrease in mean aqueous humor concentration of TNF-α in EIU rats pretreated with topical MXF (139 ± 38.6 in Group 4 vs.86.1 ± 35.5 in Group 6, p = 0.025). Also, evident suppressions were determined in mean density of NF-κB, and in mean number of cells in EIU rats pretreated either with topical AZM, or topical MXF.

CONCLUSIONS

Topically applied AZM or MXF may be beneficial in the suppression of TNF-α production in aqueous humor.

Experimental Models, Induction Protocols, and Measured Parameters in Dry Eye Disease: Focusing on Practical Implications for Experimental Research

Dry eye disease (DED) is one of the major ophthalmological healthcare challenges worldwide. DED is a multifactorial disease characterized by a loss of homeostasis of the tear film, and its main pathogenesis is chronic ocular surface inflammation related with various cellular and molecular signaling cascades. The animal model is a reliable and effective tool for understanding the various pathological mechanisms and molecular cascades in DED. Considerable experimental research has focused on developing new strategies for the prevention and treatment of DED. Several experimental models of DED have been developed, and different animal species such as rats, mice, rabbits, dogs, and primates have been used for these models. Although the basic mechanisms of DED in animals are nearly identical to those in humans, proper knowledge about the induction of animal models is necessary to obtain better and more reliable results. Various experimental models (in vitro and in vivo DED models) were briefly discussed in this review, along with pathologic features, analytical approaches, and common measurements, which will help investigators to use the appropriate cell lines, animal, methods, and evaluation parameters depending on their study design.

Ocular Distribution of Papaverine Using Non-aqueous Vehicles

Papaverine, a poorly soluble opium alkaloid, has recently been shown to reduce retinal inflammation due to which it may have therapeutic application in the management of Leber's hereditary optic neuropathy. In this study, papaverine eyedrops based on medium chain triglycerides were prepared and the effect of diethyl glycol monoethyl ether (DGME) on their ocular distribution was evaluated using an ex vivo porcine eye model. The route of drug penetration was also studied by orienting the eye to expose either only the cornea or the sclera to the formulation. Furthermore, in vivo studies were performed to confirm ocular tolerability and evaluate ocular drug distribution. Our results showed increased papaverine concentrations in the cornea and sclera in the presence of DGME but with a slight reduction in the retina-choroid (RC) drug concentration when administered via the corneal route, suggesting that DGME enhances drug accumulation in the anterior ocular tissues but with little effect on posterior drug delivery. In vivo, the papaverine eyedrop with DGME showed good ocular tolerability with the highest drug concentration being observed in the cornea (1.53 ± 0.28 μg/g of tissue), followed by the conjunctiva (0.74 ± 0.18 μg/g) and sclera (0.25 ± 0.06 μg/g), respectively. However, no drug was detected in the RC, vitreous humor or plasma. Overall, this study highlighted that DGME influences ocular distribution and accumulation of papaverine. Moreover, results suggest that for hydrophobic drugs dissolved in hydrophobic non-aqueous vehicles, transcorneal penetration via the transuveal pathway may be the predominant route for drug penetration to posterior ocular tissues. Graphical abstract.

MALDI imaging mass spectrometry revealed atropine distribution in the ocular tissues and its transit from anterior to posterior regions in the whole-eye of rabbit after topical administration

It is essential to elucidate drug distribution in the ocular tissues and drug transit in the eye for ophthalmic pharmaceutical manufacturers. Atropine is a reversible muscarinic receptor used to treat various diseases. However, its distribution in ocular tissues is still incompletely understood. Matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) evaluates drug distribution in biological samples. However, there have been few investigations of drug distribution in ocular tissues, including whole-eye segments. In the present study, we explored the spatial distribution of atropine in the whole-eye segment by MALDI-IMS, and then evaluated the changes in atropine level along the anterior-posterior and superior-inferior axes. A 1% atropine solution was administered to a rabbit and after 30 min, its eye was enucleated, sectioned, and analyzed by MALDI-IMS. Atropine accumulated primarily in the tear menisci but was found at substantially lower concentrations in the tissue surrounding the conjunctival sacs. Relative differences in atropine levels between the anterior and posterior regions provided insights into the post-instillation behavior of atropine. Atropine signal intensities differed among corneal layers and between the superior and inferior eyeball regions. Differences in signal intensity among tissues indicated that the drug migrated to the posterior regions via a periocular-scleral route. Line scan analysis elucidated atropine transit from the anterior to the posterior region. This information is useful for atropine delivery in the ocular tissues and indicates that MALDI-IMS is effective for revealing drug distribution in whole-eye sections.