Aqueous, oil, and ointment formulations of ketorolac: efficacy against prostaglandin E2-induced ocular inflammation and safety: A technical note

The efficacy of aqueous, oil, and ointment formulations of ketorolac against PGE₂-induced ocular inflammation in rabbits was evaluated, with monitoring of blinking rate and PMN and protein migration in tear fluid, following topical PGE₂ instillation. Ketorolac ophthalmic formulations protected the eye against inflammatory insult. Chronic topical administration of formulations for 10 days into rats' eyes did not lead to any appreciable gastrointestinal ulceration, which indicates that the formulations are safe for long-term use.     

Inhibition of the ocular effects of sodium arachidonate by anti-inflammatory compounds

Topical administration of aqueous solutions of sodium arachidonate to the eyes of rabbits increases intraocular pressure, constricts the pupil and increases both the protein and prostaglandin content of aqueous humor. Arachidonic acid itself dissolved in arachis oil is less effective than sodium arachidonate, although addition of polysorbate mono-oleate greatly increases the effects produced by arachidonic acid. Pretreatment with topically applied non-steroidal anti-inflammatory agents prevents the ocular effects of sodium arachidonate, indomethacin being 2–4 times as potent as either indoxole or pirprofen. Dexamethasone was without effect in these experiments. The results suggested that non-steroidal anti-inflammatory agents deserve serious consideration for topical use in the treatment of ocular inflammation.     

Effect of preservative,antioxidant and viscolizing agents on in vitro transcorneal permeation of ketorolac tromethamine

The influence of formulation additives, e.g. preservative, antioxidant and viscolizing agents on in vitro transcorneal permeation of ketorolac tromethamine from 0.5%(w/v) aqueous drop was studied using goat cornea. Permeation characteristics of drug, from selected formulations, through excised rabbit cornea were also evaluated. Aqueous solution of ketorolac tromethamine (0.5% w/v), pH 6.5 or 7.0 having ionic strength 0.2, was prepared. To this solution perservatives either alone or in combination with other additives were added to have drops of various composition. Permeation studies with goat cornea showed maximum permeation of ketorolac tromethamine from formulation containing benzalkonium chloride and disodium edetate. Increase in viscosity of drop resulted in decreased permeation of drug. Formulation containing benzalkonium chloride and disodium edetate also increased permeation of drug through rabbit cornea. Cumulative permeation of drug through rabbit cornea was found to be 2.3-2.4 fold higher than that observed with goat cornea.     

Parasite-specific antibody profile in the aqueous humor of rabbits with ocular toxocariasis

Human ocular toxocariasis is diagnosed using ophthalmologic and immunologic examinations. Many researchers have suggested that intraocular parasite-specific antibody levels are indicative of ocular toxocariasis, but little is known about the time course of the changes in these levels. We therefore investigated the anti-Toxocara canis antibody profile in the aqueous humor in an animal model of ocular toxocariasis. We intravitreally injected T. canis larvae into the right eye of 4 rabbits; 2 rabbits were orally administered T. canis eggs. We collected serum, aqueous humor, and tear samples weekly and determined the serum and aqueous humor levels of anti-T. canis immunoglobulin (Ig)G, IgA, IgM, and IgE antibodies and the tear IgG antibody level by enzyme-linked immunosorbent assay (ELISA). The severity of vitreous opacity and the aqueous humor IgG levels (measured using optical density [OD]) changed concordantly in the larvae-injected eyes; the OD exceeded 0.1 from 2–4 weeks after infection and remained elevated during active intraocular inflammation. However, the aqueous humor IgG levels were also elevated in 6 out of 8 eyes without intraocular larvae in both groups, and were low in 1 eye with live intravitreal larvae. In contrast, the serum IgG and IgM levels and the tear IgG levels increased in all rabbits, regardless of the presence of intraocular inflammation. Vitreous opacity occurred in all intravitreally infected eyes, but significant histopathological evidence of retinal damage was not detected. Thus, besides the presence of intraocular larvae, some other factors in the host may be required for the development of retinal lesions.     

SARI prevents ocular angiogenesis and inflammation in mice

SARI (Suppressor of AP-1, regulated by IFN-β) is known to play an important role in some systemic disease processes such an inflammatory conditions and cancer. We hypothesize that SARI may also play a role in ocular diseases involving inflammation and neovascularization. To explore our hypothesis, further, we investigated an endotoxin-induced uveitis (EIU) and experimental argon laser-induced choroidal neovascularization (CNV) model in SARI wild-type (SARI^WT) and SARI-deficient (SARI^−/−) mice. Through imaging, morphological and immunohistochemical (IHC) studies, we found that SARI deficiency exacerbated the growth of CNV. More VEGF-positive cells were presented in the retina of SARI^−/− mice with CNV. Compared to SARI^WT mice, more inflammatory cells infiltrated the ocular anterior segment and posterior segments in SARI^−/− mice with EIU. Collectively, the results point to a potential dual functional role of SARI in inflammatory ocular diseases, suggesting that SARI could be a potential therapy target for ocular inflammation and neovascularization.     

Simultaneous quantification of cefotaxime, desacetylcefotaxime, ofloxacine and ciprofloxacine in ocular aqueous humor and in plasma by high-performance liquid chromatography

Cefotaxime, given intravenously, is currently used as a broad-spectrum antibiotic for prophylaxis of intra- and postoperative infections in ocular lens surgery. A proposed therapeutic and economic alternative is the use of orally active fluoroquinolone ofloxacine as prophylactic agent. A HPLC method was developed for determination of both antibiotics in ocular aqueous humor and plasma in order to optimize dosage for safe surpassing minimal inhibitory concentration in the humor compartment. For plasma determinations a solid-phase extraction procedure was used with ciprofloxacine as internal standard. Detection limits for direct HPLC-analysis of ocular aqueous humor was 0.08 μg/ml for all compounds, whereas in plasma 0.31 μg/ml could be determined after solid-phase extraction.     

Control of Transdermal Permeation of Hydrocortisone Acetate from Hydrophilic and Lipophilic Formulations

The purpose of this research was the preparation of four formulations containing hydrocortisone acetate (HCA) for topical application, including two aqueous systems (hydrophilic microemulsion and aqueous gel) and two systems with dominant hydrophobicity (hydrophobic microemulsion and ointment). The formulations were tested for the release and permeation of HCA across an animal membrane. The release of HCA was found comparable for the four systems. The two microemulsions promote permeation across an ex-vivo membrane, examined by means of a Franz cell. Hydrophobic microemulsion guarantees the highest solubility (2,370 μg/ml) and flux (133 μg/cm².h) of the drug, since it contains almost 40% Transcutol, a permeation enhancer. Gel and ointment provide lower solubility and flux, being the values, related to the ointment, the lowest ones (562 μg/ml and 0.4 μg/cm².h). Experimental results allow the conclusion that gel and ointment can be suitable when it is desirable to minimize absorption of topically applied HCA as to keep the drug restricted to the diseased area and prevent side effects of the systemic presence of HCA.     

Aquaporins in the eye: Expression,function, and roles in ocular disease

Background

All thirteen known mammalian aquaporins have been detected in the eye. Moreover, aquaporins have been identified as playing essential roles in ocular functions ranging from maintenance of lens and corneal transparency to production of aqueous humor to maintenance of cellular homeostasis and regulation of signal transduction in the retina.

Scope of review

This review summarizes the expression and known functions of ocular aquaporins and discusses their known and potential roles in ocular diseases.

Major conclusions

Aquaporins play essential roles in all ocular tissues. Remarkably, not all aquaporin function as a water permeable channel and the functions of many aquaporins in ocular tissues remain unknown. Given their vital roles in maintaining ocular function and their roles in disease, aquaporins represent potential targets for future therapeutic development.

General significance

Since aquaporins play key roles in ocular physiology, an understanding of these functions is important to improving ocular health and treating diseases of the eye. It is likely that future therapies for ocular diseases will rely on modulation of aquaporin expression and/or function. This article is part of a Special Issue entitled Aquaporins.     

Light-dark variations in ocular timolol concentrations following topical solution instillation in the pigmented rabbit.

The objective of this study was to determine whether ocular absorption of topically applied timolol in the pigmented rabbit varied with the time of drop instillation. Twenty-five microliters of a 0.65% timolol maleate solution were instilled in the pigmented rabbit eye at 0600, 0900, 1200, 1500, 1800, 2100, 2400, or 0300 hr. Timolol concentrations in the conjunctiva, sclera, corneal epithelium, corneal stroma, aqueous humor, and iris-ciliary body at 15 and 30 min post-dosing were monitored using reversed phase HPLC. Ocular timolol concentrations were higher when the drug was administered during the light period (0900-1800 hr) than when it was administered during the dark period (1800-0600 hr). There exist, therefore, light-dark variations in the ocular absorption of topically applied timolol.     

Feline ocular chlamydiosis: clinical and microbiological effects of topical and systemic therapy

Conjunctival swabs taken from a two-month-old kitten showing ocular discharge were found to be positive for Chlamydophila felis by PCR and isolation. The cat was treated with topical 1% tetracycline ophthalmic ointment twice a day for 60 days. At the end of the treatment, the cat showed no ocular signs and conjunctival swabs resulted PCR and isolation negative for C. felis. Forty days later, the ocular discharge recurred and C. felis was isolated from conjunctival swabs taken from both the cat's eyes. Twenty days of doxycycline systemic treatment at 10 mg/kg once daily was started. The treatment resulted in a complete clinical recovery after a few days. C. felis was not isolated or amplified on the 10th day after beginning the treatment. The cat's conjunctival swabs were also PCR and isolation negative on the 10th, 30th, 60th, 90th, 120th and 240th days after the end of therapy.     

Changes in ocular tone, pH, ascorbic acid and lactic acid concentration in the aqueous humor of rabbits treated with aceclidine

The Authors state the results of their research on the modification of the aqueous humor caused by the instillation of the Clonidina to the concentrations of 0,I25% in a group of ten rabbits. The results of these studies illustrate the variations of pH, the ocular tone, the concentration of lactic and ascorbic acid. In all the rabbits examined Clonidina was instillated in the RE while in the LE distilled water was instillated for the control. For two hours from the beginning of the experiment, every IO minutes measurements of the ocular tone in both eyes were taken. At the end of the two hours a sample of aqueous humor was taken from the RE and LE; It was found that: I) The drugs produced a very quick and prolonged decrease of the ocular tone. 2) There are no significant variations in the pH or in the concentration of lactic acid. 3) There was a notable reduction of the concentration of ascorbic acid.     

Long non-coding RNAs: new players in ocular neovascularization

Pathological neovascularization are the most prevalent causes of moderate or severe vision loss. Long non-coding RNAs (lncRNAs) have emerged as a novel class of regulatory molecules involved in numerous biological processes and complicated diseases. However, the role of lncRNAs in ocular neovascularization is still unclear. Here, we constructed a murine model of ocular neovascularization, and determined lncRNA expression profiles using microarray analysis. We identified 326 or 51 lncRNAs that were significantly either up-regulated or down-regulated in the vaso-obliteration or neovascularization phase, respectively. Based on Pearson correlation analysis, lncRNAs/mRNAs co-expression networks were constructed. GO enrichment analysis of lncRNAs-co-expressed mRNAs indicated that the biological modules were correlated with chromosome organization, extracellular region and guanylate cyclase activator activity in the vaso-obliteration phase, and correlated with cell proliferation, extracellular region and guanylate cyclase regulator activity in the neovascularization phase. KEGG pathway analysis indicated that MAPK signaling was the most significantly enriched pathway in both phases. Importantly, Vax2os1 and Vax2os2 were not only dynamically expressed in the vaso-obliteration and neovascularization phases, but also significantly altered in the aqueous humor of patients with neovascular age-related macular degeneration (AMD), suggesting a potential role of lncRNAs in the regulation of ocular neovascularization. Taken together, this study provided novel insights into the molecular pathogenesis of ocular neovascularization. The intervention of dysregulated lncRNA could become a potential target for the prevention and treatment of ocular vascular diseases.     

Clear,Aqueous Topical Drop of Triamcinolone Acetonide

The objective of this study was to develop a clear aqueous mixed nanomicellar formulation (NMF) of triamcinolone acetonide (TA) with a combination of nonionic surfactant hydrogenated castor oil 60 (HCO-60) and octoxynol-40 (Oc-40). In order to delineate the effects of drug-polymer interactions on entrapment efficiency (EE), loading efficiency (LE), and critical micellar concentration (CMC), a design of experiment (DOE) was performed to optimize the formulation. In this study, full-factorial design has been used with HCO-60 and OC-40 as independent variables. All formulations were prepared following solvent evaporation and film rehydration method, characterized with size, polydispersity, shape, morphology, EE, LE, and CMC. A specific blend of HCO-60 and Oc-40 at a particular wt% ratio (5:1.5) produced highest drug EE, LE, and smallest CMC (0.0216 wt%). Solubility of TA in NMF improved 20 times relative to normal aqueous solubility. Qualitative ¹H NMR studies confirmed the absence of free drug in the outer aqueous NMF medium. Moreover, TA-loaded NMF appeared to be highly stable and well tolerated on human corneal epithelial cells (HCEC) and human retinal pigment epithelial cells (D407 cells). Overall, these studies suggest that TA in NMF is safe and suitable for human topical ocular drop application.     

Development of Novel Microemulsion-Based Topical Formulations of Acyclovir for the Treatment of Cutaneous Herpetic Infections

The present investigation aims at developing microemulsion-based formulations for topical delivery of acyclovir. Various microemulsions were developed using isopropyl myristate/Captex 355/Labrafac as an oil phase, Tween 20 as surfactant, Span 20 as cosurfactant, and water/dimethylsulfoxide (1:3) as an aqueous phase. Transcutol, eucalyptus oil, and peppermint oil were used as permeation enhancers. In vitro permeation studies through laca mice skin were performed using Franz diffusion cells. The optimum formulation containing 2.5% Transcutol as the penetration enhancer showed 1.7-fold enhancement in flux and permeation coefficient as compared to marketed cream and ointment formulation. In vivo antiviral studies were performed in female Balb/c mice against induced herpes simplex virus I infection. A single application of microemulsion formulation containing 2.5% Transcutol given 24 h post-injection resulted in complete suppression of development of herpetic skin lesions.     

Nanomaterials for ocular drug delivery

Efficient drug delivery to the eye remains a challenging task for pharmaceutical scientists. Due to the various anatomical barriers and the clearance mechanisms prevailing in the eye, conventional drug delivery systems, such as eye drop solutions, suffer from low bioavailability. More invasive methods, such as intravitreal injections and implants, cause adverse effects in the eye. Recently, an increasing number of scientists have turned to nanomaterial-based drug delivery systems to address the challenges faced by conventional methods. This paper highlights recent applications of various nanomaterials, such as polymeric micelles, hydrogels, liposomes, niosomes, dendrimers, and cyclodextrins as ocular drug delivery systems to enhance the bioavailability of ocular therapeutic agents.     

Tear cytokine and ocular surface alterations following brief passive cigarette smoke exposure

Purpose: To prospectively investigate the effects of acute passive cigarette smoke exposure on the ocular surface and tear film in healthy non-smokers. Methods: Twelve right eyes of 12 subjects without any ocular diseases were examined before, 5 min, and 24 h after 5 min of passive cigarette smoke exposure in a controlled smoke chamber. Tear samples were obtained before, 5 min and 24 h after smoke exposure to detect tear hexanoyl-lysine (HEL), acrolein and inflammatory cytokine concentrations. Tear evaporation rate, DR-1 tear film lipid layer interferometry, tear film break-up time (TBUT), ocular surface fluorescein staining (FS) and Rose Bengal staining (RB), Schirmer I test were performed before, 5 min, and 24 h after smoke exposure. Conjunctival impression cytology (IC) and brush cytology (BC) were carried out before and 24 h after smoke exposure. Results: Tear evaporation rate, tear lipid spread time, tear film break-up time, and vital staining scores showed significant worsening with passive smoke exposure. Tear HEL and IL-6 concentrations increased significantly 24 h after smoke exposure. Tear acrolein level showed an insignificant increase at 5 min. IC and RT-PCR revealed a significant reduction in goblet cell density, a shift toward higher squamous metaplasia grades and a significant downregulation of MUC5AC mRNA expression at 24 h. Conclusion: Even brief passive exposure to cigarette smoke in healthy non-smoker subjects was associated with adverse effects on the ocular surface health as evidenced by an increase of tear inflammatory cytokines, tear lipid peroxidation products and decrease of mucosal defense resulting in tear instability and damage to the ocular surface epithelia.     

d-Ibuprofen in ocular inflammation induced by paracentesis of the rabbit eye

The anti-inflammatory compound d-ibuprofen has been investigated for anti-inflammatory and cyclooxygenase inhibitory activity in ocular inflammation induced by paracentesis of eyes of living rabbits. d-Ibuprofen is the dextro-rotary isomer of ibuprofen, a potent non-steroidal anti-inflammatory agent. Eyes pretreated topically with d-ibuprofen 0.8% showed a significant inhibition of aqueous protein (73.0%) and prostaglandin E2 (96.4%) increase after paracentesis as compared to paracentesized untreated fellow eyes and control eyes. In aqueous humor no significant correlation between the increase in prostaglandin E2 and protein could be established after paracentesis. These results indicate that d-ibuprofen could be a useful ocular anti-inflammatory agent as cyclooxygenase inhibitor.     

Effect of intraocular silicone oil on ocular tissue

The aim of this study was to find out to which extent the instilled silicone oil affects the changes of lens, cornea, and the ocular pressure with regard to its time kept in the operated eye with a lens. The study was carried out on the sample of 40 patients, divided in three groups. The first group of patients with the silicone oil kept in the eye during 3 months, the second one during 3-6 months, and the third one during 6-9 months. Statistically important changes were observed in the progression of the lens opacification with the patients, progressively with the time of keeping the silicone oil in the eye. The followed cornea opacifications and increased ocular pressure were not statistically significantly linked with the length of keeping the silicone oil in the eye, so that it can be concluded that the silicone oil is the best substitute for the vitreous body but it should be removed from the eye, most frequently, in the period of 3-6 months from the date of its instillation, and after 3 weeks at the earliest.     

Microbiological analysis of conjunctival secretion in anophthalmic cavity,contralateral eye and ocular prosthesis of patients with maxillofacial abnormalities

The purpose of this study was to identify and analyse the micro‐organisms present in the conjunctival secretion in anophthalmic cavities of wearers of ocular prostheses, as well as on the prostheses used by them, correlating them with the microbiota of the contralateral eye. Nine patients with maxillofacial abnormalities, wearers of an acrylic resin ocular prosthesis participated in the study. Collections of conjunctival secretions and biofilm were performed on the prosthesis, anophthalmic cavity and contralateral eye for the mycological and bacterial analyses. The data were submitted to statistical analysis, performing a Kendall correlation test to identify the correlation between the collection site and the identified micro‐organism (P < 0·05). It was verified that the most prevalent micro‐organisms were the Staphylococcus aureus and Staphylococcus epidermidis, independent of the collection site, and that negative cultures for fungi were encountered in 85·2% of collections, independent of the region. It was not possible to establish a correlation among the types of micro‐organisms and the collection sites.

Significance and Impact of the Study

Some evidence suggests that the surface roughness of ocular prostheses can influence interactions with micro‐organisms, with greater prejudicial consequences, such as the establishment of biofilms, which could lead to infections. Thus, it becomes extremely important to identify the micro‐organisms present on the acrylic surfaces of ocular prostheses, as well as the microbiota of the anophthalmic cavity and contralateral eye of wearers of the same, so that subsequent control measures promote the homeostatic maintenance of the ocular region.     

Normal color variations of the canine ocular fundus, a retrospective study in Swedish dogs

Background  

A retrospective study was made to demonstrate normal variations of the color and size of the tapetal area and color of the nontapetal area in the ocular fundus in dogs, correlating them to breed, age and coat color.