Steroidal nanoformulations for the treatment of uveitis: potential, promises and future perspectives

BACKGROUND

Intraocular inflammation, commonly referred to as uveitis, is a prevalent ocular disease. The categorization of uveitis may be based on the prevailing anatomical site, which includes anterior, intermediate, and posterior uveitis. There exists a significant body of evidence indicating that T cells play a pivotal role in the pathogenesis of autoimmune uveitis. In addition to the presence of T cells, an elevation in levels of inflammatory cytokines and a reduction in regulatory cytokines were also noted. The primary pharmacological interventions for uveitis comprise of corticosteroids, methotrexate, anti-vascular endothelial growth factor (VEGF) agents, anti-tumor necrosis factor-alpha (TNF-α) antibodies, and sirolimus. These medications offer prompt alleviation for inflammation. Nevertheless, prolonged administration of corticosteroids invariably leads to unfavorable adverse reactions. The traditional topical corticosteroids exhibit certain limitations, including inadequate transcorneal permeation and low corneal retention, leading to reduced ocular bioavailability. Consequently, there is a growing inclination towards the creation of innovative steroid drug delivery systems with the aim of reducing the potential for adverse effects, while simultaneously enhancing the drug's corneal permeation and retention.

CONCLUSION

This review is an attempt to compile all the research work done so far in this field and provides a brief overview of the global efforts to develop innovative nanocarrier-based systems for corticosteroids.

Controlled release, chitosan-tethered luteolin phytocubosomes; Formulation optimization to in-vivo antiglaucoma and anti-inflammatory ocular evaluation

A chitosan-coated luteolin-loaded phytocubosomal system was prepared to improve the pharmacodynamic performance of luteolin in the treatment of glaucoma and ocular inflammation after topical ocular administration. Luteolin, a potent anti-oxidant herbal drug with poor aqueous solubility, was complexed with phospholipid. The prepared phytocubosomes were coated with chitosan, producing homogenously distributed nanosized particles (258 ± 9.05 nm) with a positive charge (+49 ± 6.09 mV), improved EE% (96 %), and increased concentration of encapsulated drug to 288 μg/ml. Polarized light microscopy revealed a cubic phase. Chitosan-coated phytocubosomes showed a sustained drug release profile (38 % over 24 h) and improved anti-oxidant activity (IC50 of 32 μg/ml). Ex vivo transcorneal permeation was higher by 3.60 folds compared to luteolin suspension. Irritancy tests confirmed their safety in ocular tissues after single and multiple administrations. The pharmacodynamic studies on glaucomatous rabbit eyes demonstrated 6.46-, 3.88-, and 1.89-fold reductions in IOP of chitosan-coated phytocubosomes compared to luteolin suspension, cubosomes, and phytocubosomes, respectively. Pharmacodynamic anti-inflammatory studies revealed faster recovery capabilities of chitosan-coated phytocubosomes over other formulations. Thus, chitosan-coated phytocubosomes could be a promising ocular hybrid system for delivering herbal lipophilic drugs such as luteolin.

Quality of dorzolamide hydrochloride and timolol maleate containing eye drops distributed online

Patient safety risks associated with the online purchase of medications, especially in case of ophthalmic preparations, are significant. Our study aimed to carry out quality assessment of dorzolamide hydrochloride (DZA) and timolol maleate (TIM) eye drops preserved with benzalkonium chloride (BAC) via online test purchases. Three samples were purchased online, while control preparations were acquired through authorized national drug supply chain. Our method was based on the International Pharmaceutical Federation (FIP) Inspection Checklist and integrated the evaluation of packaging and labelling. Sterility was established according to the European Pharmacopoeia (Ph. Eur.), while qualitative and quantitative quality was assessed with high-performance liquid chromatographic (HPLC) analysis. Several signs of falsification were recognized upon visual inspection of the online samples. All the products were clear, colourless, slightly viscous solutions. They were free from visible contaminants. The samples were sterile as no evidence of microbial growth was found. A quick and inexpensive HPLC analysis, optimized by the authors showed that active ingredients and the preservative deviated significantly (p < 0,05) with more than 10% from the values stated on the labels for at least one component (DZA: 99.3-113.1%, TIM: 112.8-139.2%, BAC: 82.4-97.7%). Development of comprehensive and reliable quality assessment methods are vital to increase public safety of pharmaceutical products sold online. A complex approach, integrating visual inspection, labelling assessment, microbiological analysis coupled with qualitative and quantitative methods provide a most reliable method. Due to its limited feasibility and cost-effectiveness, raising public awareness and limiting illegal online sellers should be the primary approaches to protect patients from substandard and falsified medicinal products sold via the internet. Particularly important for health professionals to understand this market and its public health concern, and to raise patient awareness of the risks associated with uncontrolled online purchase of medication.

Oxygen-Carrying Capacity of Perfluorohexyloctane, a Novel Eye Drop for Dry Eye Disease

Objective

One-hundred percent perfluorohexyloctane (PFHO) is a water-free, preservative-free eye drop approved by the Food and Drug Administration in the United States for the treatment of dry eye disease. PFHO has shown relief of dry eye signs and symptoms in clinical trials and has potent antievaporative action in vitro. The objective of this study was to measure the level of oxygen in PFHO.

Methods

T1 relaxation times (time taken for proton spins to translate from a random alignment to an alignment with the main magnetic field) for fluorine-19 in perfluorohexyloctane were measured using fluorine-19 nuclear magnetic resonance spectroscopy. The level of oxygen was interpolated from published data.

Results

The hydrogen-1 and fluorine-19 nuclear magnetic resonance spectra of PFHO were well resolved and the resonance assignments and intensities were as expected. The T1 values calculated for the CF₃ group resonance in the current study was 0.901 seconds and 1.12 seconds at 25 °C and 37 °C, respectively. The T1 values for the CF₂ group resonances increased by 17% to 24% with an increase in temperature from 25 °C to 37 °C. The mean (SD) partial pressure of oxygen in PFHO was calculated to be 257 (36) mm Hg and 270 (38) mm Hg at 25 °C and 37 °C, respectively.

Conclusions

The current study confirms that PFHO contains a significant amount of oxygen, more so than that calculated for tears in equilibrium with air. Once instilled on the eye, PFHO is not expected to be a barrier to the oxygen necessary for a healthy cornea and may in fact deliver nonreactive oxygen to the cornea to facilitate healing in patients with dry eye disease.

Optic Pathway Gliomas: The Trends of Basic Research to Reduce the Impact of the Disease on Visual Function

Pediatric optic pathway gliomas (OPG) are low-grade brain tumors characterized by slow progression and invalidating visual loss. Common therapeutic strategies include surgery, radiotherapy, chemotherapy, and combinations of these modalities, but despite the different treatment strategies, no actual treatment exists to prevent or revert visual impairment. Nowadays, several reports of the literature show promising results regarding NGF eye drop instillation and improvement of visual outcome. Such results seem to be related with the NGF-linked prevention in caspase activation, which reduces retinal ganglion cell loss.Reducing retinal ganglion cell loss results clinically in visual field improvement as well as visual electric potential and optical coherence tomography gain. Nonetheless, visual acuity fails to show significant changes.Visual impairment represents nowadays one of the major issues in dealing with OPGs. Secondary to the interesting results offered by NGF eye drop administration, further studies are warranted to better comprehend potential treatment strategies.

Assessment of eye drop instillation techniques among patients with primary open angle glaucoma in a Nigerian tertiary hospital

PURPOSE

To assess the technique of eye drop instillation and its determinants among patients with primary open angle glaucoma (POAG) attending a Nigerian tertiary hospital.

METHODS

This study was a cross-sectional observational study conducted among 130 participants. Systematic sampling technique was used. Inclusion criteria were the presence of POAG, in individuals ≥ 18 years, and self-instilling their ocular hypotensive medications for at least 6 months. Demographic data and clinical characteristics were obtained using an interviewer-administered questionnaire and clinical examination. All participants underwent eye drop instillation of sterile water. Administration techniques were observed and graded using a comprehensive grading scheme. Patients with poor techniques were educated. Determinants of poor eye drop administration technique were also explored.

RESULTS

One hundred and thirty patients with POAG were studied. The mean age was 57.13 ± 13.20 years, and 63% percent of the participants had poor eye drop administration technique. On multivariate analysis, previous eye drop instillation education significantly influenced eye drop instillation technique (p = 0.02; OR = 3.230; 95% CI = 1.173-8.896). Among the participants, 47 (36%) touched the globe, 128 (98.5%) did not wash their hands, and 126 (97%) did not occlude the punctum. Sequel to the training, mean score of subjects improved from 2.8 ± 1.1 to 4.1 ± 1.3 (p value < 0.001).

CONCLUSION

This study demonstrated that a high proportion of POAG patients had poor eye drop instillation technique despite long-term self-use of topical medication. Thus, this aspect of therapy deserves periodic scrutiny by the clinician.

A non-invasive nanoparticle-based sustained dual-drug delivery system as an eyedrop for endophthalmitis

Endophthalmitis is an infectious disease that affects the entire eye spreading to the internal retinal layers and the vitreous and causes severe sight-threatening conditions. Current treatment strategies rely on intraocular injections of antibiotics that are invasive, may lead to procedural complications and, ultimately, blindness. In this study, we developed a non-invasive strategy as an eyedrop containing nanoparticle-based dual-drug delivery system in which the hydrophobic poly-L-lactide core was loaded with azithromycin or triamcinolone acetonide, and the hydrophilic shell was made of chitosan. The developed nanoparticles were ~200-250 nm in size, spherical in shape, moderately hydrophilic, lysozyme tolerant, cytocompatible, and hemocompatible. Application of these chitosan-coated nanoparticles as eye drops to C57BL/6 mice showed higher bioavailability in choroid and retina when compared to the uncoated nanoparticles. The delivery system showed sustained release of drug for 300 h and exhibited antimicrobial effects against Gram-positive and Gram-negative bacteria and anti-inflammatory effects on activated microglial cells. Interestingly, the combination of the nanoparticles loaded with azithromycin and the nanoparticles loaded with triamcinolone acetonide acted synergistically as compared to either of the nanoparticles/drugs alone. Overall, the developed dual-drug delivery system is non-invasive, has antimicrobial and anti-inflammatory effects, and shows potential as an eye drop formulation against endophthalmitis.

Synthetic high-density lipoprotein nanoparticles: Good things in small packages

Medicine has been a great beneficiary of the nanotechnology revolution. Nanotechnology involves the synthesis of functional materials with at least one size dimension between 1 and 100 nm. Advances in the field have enabled the synthesis of bio-nanoparticles that can interface with physiological systems to modulate fundamental cellular processes. One example of a diverse acting nanoparticle-based therapeutic is synthetic high-density lipoprotein (HDL) nanoparticles (NP), which have great potential for treating diseases of the ocular surface. Our group has developed a spherical HDL NP using a gold nanoparticle core. HDL NPs: (i) closely mimic the physical and chemical features of natural HDLs; (ii) contain apoA-I; (iii) bind with high-affinity to SR-B1, which is the major receptor through which HDL modulates cell cholesterol metabolism and controls the selective uptake of HDL cargo into cells; (iv) are non-toxic to cells and tissues; and (v) can be chemically engineered to display nearly any surface or core composition desired. With respect to the ocular surface, topical application of HDL NPs accelerates re-epithelization of the cornea following wounding, attenuates inflammation resulting from chemical burns and/or other stresses, and effectively delivers microRNAs with biological activity to corneal cells and tissues. HDL NPs will be the foundation of a new class of topical eye drops with great translational potential and exemplify the impact that nanoparticles can have in medicine.

Efficacy and safety of 0.01% atropine for prevention of childhood myopia in a 2-year randomized placebo-controlled study

PURPOSE

Atropine eye drops prevent the progression of myopia, but their use has not been tested in the Japanese schoolchildren population. Here, we evaluate the efficacy and safety of 0.01% atropine eye drops for myopia control in Japanese children.

STUDY DESIGN

Multicenter (7 university hospitals), randomized, double-masked, placebo-controlled trial.

METHODS

Participants were 171 Japanese schoolchildren aged 6 to 12 years, with progressive myopia, spherical equivalence (SE) of -1.00 to -6.00 diopters (D), and astigmatism of ≤1.5 D. They were randomized to receive either 0.01% atropine (n=85) or placebo (n=86) eye drops once nightly OU for 24 months. Primary and secondary efficacy endpoints were changes in SE and axial length (AL), respectively, from baseline to month 24.

RESULTS

Data from 168 subjects were analyzed. At month 24, compliance was similar in both groups (atropine: 83.3%; placebo: 85.7%). The least squares mean change in SE and AL from baseline were, respectively, -1.26 D (95% confidence interval [CI]: -1.35, -1.17) and 0.63 mm (0.59, 0.67) for atropine and -1.48 D (- 1.57, -1.39) and 0.77 mm (0.73, 0.81) for placebo. Inter-group differences were 0.22 D (95% CI: 0.09, 0.35; P < 0.001) for SE and - 0.14 mm (-0.20, -0.08; P < 0.001) for AL. Three patients experienced mild allergic conjunctivitis side effects, with no inter-group difference in incidence (atropine: 2.4%; 2/84 patients; placebo: 1.4%; 1/84 patients).

CONCLUSION

With good compliance, 0.01% atropine is effective and safe for preventing the progression of childhood myopia.

Imprinted β-ketoenamine-linked covalent organic frameworks as dispersive sorbents for the fluorometric determination of timolol

Timolol accompanied the formation of fluorescent β-ketoenamine-linked covalent organic frameworks (COFs) via the Sc(Tof)₃-catalyzed condensation of derivated carbaldehyde and hydrazide in a 1,4-dioxane/mesitylene porogen to construct timolol-imprinted COFs (TICOFs). With high imprinting factors, the synthesis-optimized TICOFs were characterized by fluorescence, UV-Vis spectrometry, X-ray diffraction, N₂ adsorption/desorption analyses, scanning electron microscopy, and FTIR spectrometry. The TICOF fluorescence measured at 390 nm/510 nm is dynamically quenched by timolol and was thus utilized to quantify timolol in a linear range of 25-500 nM with a LOD of 8 nM. The TICOF recovered 99.4% of 0.5% timolol maleate in a commercial eye drop (RSD = 1.1%, n = 5). In addition, TICOF was used as a dispersive sorbent to recover 95% of 2.0 nM timolol from 20 mg of TICOF in 25 mL phosphate buffer. Dilution factors of 25 and 75 were the maximum tolerated proportions of the urine and serum matrix spiked with 2.0 nM timolol to reach recoveries of 92.4% and 90.3%, respectively.

Topical ocular pharmacokinetics and bioavailability for a cocktail of atenolol, timolol and betaxolol in rabbits

Ocular bioavailability after eye drops administration is an important, but rarely determined, pharmacokinetic parameter. In this study, we measured the pharmacokinetics of a cocktail of three beta blockers after their topical administration into the albino rabbit eye. Samples from aqueous humour were analysed with LC-MS/MS. The pharmacokinetic parameters were estimated using compartmental and non-compartmental analyses. The ocular bioavailability was covering broad range of values: atenolol (0.07 %), timolol (1.22%, 1.51%) and betaxolol (3.82%, 4.31%). Absolute ocular bioavailability presented a positive trend with lipophilicity and the values showed approximately 60-fold range. The generated data enhances our understanding for ocular pharmacokinetics of drugs and may be utilized in pharmacokinetic model building in ophthalmic drug development.

Distribution of 14C-Latanoprost Following a Single Intracameral Administration Versus Repeated Topical Administration

Purpose

To qualitatively evaluate the ocular and periocular distribution of ¹⁴C-latanoprost following a single intracameral administration or repeated topical ocular administration in beagle dogs and cynomolgus monkeys.

Methods

In the dog study, three animals received an intracameral dose of ¹⁴C-latanoprost bilaterally and were euthanized at 1, 2, and 4 h post dose; three control animals received topical ¹⁴C-latanoprost bilaterally once daily for 5 days and were euthanized at 1, 4, and 24 h post final dose. Sagittal 40-µm sections of eyes with surrounding tissues were collected and processed for autoradiography. Methods in the monkey study were similar; two animals received a unilateral intracameral dose of ¹⁴C-latanoprost.

Results

After intracameral dosing in dogs, radioactivity was concentrated in the cornea, iris, ciliary body, and anterior chamber with no radioactivity detected in the eyelids or other periorbital tissues. After topical dosing, radioactivity was distributed in the bulbar conjunctiva, cornea, anterior chamber, iris, ciliary body, upper and lower eyelids, and periorbital tissues (fat/muscle). After intracameral dosing in monkeys, radioactivity was concentrated in the anterior chamber, cornea, iris, ciliary body, and posteriorly along the uveoscleral outflow pathway; there was no radioactivity in the eyelids or periorbital tissues aside from signal in the nasolacrimal duct, likely from reflux of ¹⁴C-latanoprost into the tear film.

Conclusions

Intracameral delivery resulted in more selective target tissue drug exposure. Intracameral drug delivery has potential to reduce ocular surface and periocular adverse effects associated with topical administration of prostaglandin analogues, such as eyelash growth and periorbital fat atrophy.

Electronic supplementary material

The online version of this article (10.1007/s40123-020-00285-3) contains supplementary material, which is available to authorized users.

Topical administration of rapamycin promotes retinal ganglion cell survival and reduces intraocular pressure in a rat glaucoma model

Glaucoma is a progressive optic neuropathy that has become the most common cause of irreversible blindness worldwide. Studies have shown that the protein mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a central role in regulating numerous functions, such as growth, proliferation, cytoskeletal organization, metabolism, and autophagy. Clinical trials have shown that Rho-associated protein kinase (ROCK) inhibitors reduced intraocular pressure (IOP) in patients with glaucoma and ocular hypertension (OHT). In this study, we explored whether rapamycin (RAPA) eye drops can reduce IOP and protect retinal ganglion cells (RGCs). Our results indicated that in rats treated with RAPA, the drug was detected in the aqueous humor (AH), and the IOP was reduced. This may be related to the inhibition of RhoA protein activation by RAPA and regulation of the actin cytoskeleton in trabecular meshwork (TM) cells. In addition, the retinal thickness and the survival rate of RGCs were significantly reduced in the OHT group compared with the control group. These changes in the OHT group were significantly improved after treatment with RAPA. This may be because RAPA inhibited the activation of glial cells and the release of proinflammatory factors, thereby attenuating further damage to the retina and RGCs. Taken together, the results of this study demonstrated that RAPA not only reduced IOP but also protected RGCs, suggesting that RAPA is likely to be an effective strategy for the treatment of glaucoma.

Advances and limitations of drug delivery systems formulated as eye drops

Topical instillation of eye drops remains the most common and easiest route of ocular drug administration, representing the treatment of choice for many ocular diseases. Nevertheless, low ocular bioavailability of topically applied drug molecules can considerably limit their efficacy. Over the last several decades, numerous drug delivery systems (DDS) have been developed in order to improve drug bioavailability on the ocular surfaces. This review systematically covers the most recent advances of DDS applicable by topical instillation, that have shown better performance in in vivo models compared to standard eye drop formulations. These delivery systems are based on in situ forming gels, nanoparticles and combinations of both. Most of the DDS have been developed using natural or synthetic polymers. Polymers offer many advantageous properties for designing advanced DDS including biocompatibility, gelation properties and/or mucoadhesiveness. However, despite the high number of studies published over the last decade, there are several limitations for clinical translation of DDS. This review article focuses on the recent advances for the development of ocular drug delivery systems. In addtion, the potential challenges for commercialization of new DDS are presented.

A case of drug induced lung injury caused by levofloxacin eye drops

A 78 year-old man, who received levofloxacin eye drops as a perioperative prophylactic antibacterial agent for cataract surgery, developed pyrexia and dyspnea, followed by respiratory failure. He was diagnosed as drug-induced lung injury due to levofloxacin, and the symptoms improved after the administration of corticosteroids and discontinuation of levofloxacin eye drops. The incidence of levofloxacin-induced lung injury is rare for its frequent prescription. Moreover, eye drops of it has never been reported to cause lung injury. We should be aware of eye drops as a causative dosage forms of drug-induced lung injury.

Cell penetrating peptides in ocular drug delivery: State of the art

Despite the increasing number of effective therapeutics for eye diseases, their treatment is still challenging due to the presence of effective barriers protecting eye tissues. Cell Penetrating Peptides (CPPs), synthetic and natural short amino acid sequences able to cross cellular membrane thanks to a transduction domain, have been proposed as possible enhancing strategies for ophthalmic delivery. In this review, a general description of CPPs classes, design approaches and proposed cellular uptake mechanisms will be provided to the reader as an introduction to ocular CPPs application, together with an overview of the main problems related to ocular administration. The results obtained with CPPs for the treatment of anterior and posterior segment eye diseases will be then introduced, with a focus on non-invasive or minimally invasive administration, shifting from CPPs capability to obtain intracellular delivery to their ability to cross biological barriers. The problems related to in vitro, ex vivo and in vivo models used to investigate CPPs mediated ocular delivery will be also addressed together with potential ocular toxicity issues.

Eyelid skin as a potential site for drug delivery to conjunctiva and ocular tissues

The feasibility of topical application onto the (lower) eyelid skin to deliver hydrophilic and lipophilic compounds into the conjunctiva and ocular tissues was evaluated by comparing with conventional eye drop application. Skin permeation and the concentration of several model compounds, and skin impedance were determined utilizing eyelid skin from hairless rats, as well as abdominal skin in the same animals for comparison. In vitro static diffusion cells were used to assess the skin permeation in order to provide key insights into the relationship between the skin sites and drugs. The obtained results revealed that drug permeation through the eyelid skin was much higher than that through abdominal skin regardless of the drug lipophilicity. Specifically, diclofenac sodium salt and tranilast exhibited approximately 6-fold and 11-fold higher permeability coefficients, respectively, through eyelid skin compared with abdominal skin. Histomorphological evaluation and in vivo distribution of model fluorescent dyes were also examined in the conjunctiva and skin after eyelid administration by conventional microscope and confocal laser scanning microscope analyses. The result revealed that eyelid skin has a thinner stratum corneum, thereby showing lower impedance, which could be the reason for the higher drug permeation through eyelid skin. Comparative evaluation of lipophilic and hydrophilic model compounds administered via the eyelid skin over 8h revealed stronger fluorescence intensity in the skin and surrounding tissues compared with eye drop administration. These results suggested that the (lower) eyelid skin is valuable as a prospective site for ophthalmic medicines.

Short-term Analysis of the Residual Volume of an Eye Drop Following 23-Gauge Microincision Vitrectomy Surgery

Purpose

To evaluate the change of residual volume of eye drop after instillation in patients with 23-gauge microincision vitrectomy surgery (MIVS).

Methods

Patient who were treated 23-gauge MIVS from November 2014 to July 2015 were included. The residual volume was defined as the amount of remnant eye drop in patient's eyes after instillation, calculated as the difference between instillation volume and spilled volume of eye drop. Calculation of residual volume of eye drop was performed one day before surgery, and daily from postoperative day 1 to day 5.

Results

Forty consecutive patients were included. The residual volume of eye drop decreased from 30.3 ± 1.4 µL at baseline to 13.0 ± 1.5 µL at day 1, 18.3 ± 1.6 µL at day 2, 24.7 ± 1.5 µL at day 3, and 27.9 ± 1.4 µL in day 4, postoperatively (p < 0.001, respectively). The volume at postoperative day 5 was 29.4 ± 1.3 µL, but it was not different from the volume at baseline (p = 0.105). The change of residual volume was significantly correlated with postoperative chemosis (r = 0.672, p < 0.001) and effected by the number of quadrant with postoperative chemosis (p < 0.05).

Conclusions

This study shows that postoperative residual volume of eye drop after instillation decreased until postoperative day 4, and postoperative chemosis affects the change of residual volume. Thus, checking proper use of eye drops and teaching about instillation technique by physician is necessary for patients with 23-gauge MIVS.

Determination of phosphate concentration in glaucoma eye drops commercially available in Spain

OBJECTIVES

To identify and analyze the phosphate concentration in glaucoma eye drops available in Spain.

MATERIAL AND METHODS

Glaucoma medications containing phosphates were identified according to the 2013 Vademecum and the website of the Spanish Agency for Medicines and Medical Devices. Phosphate concentration was determined in these eye drops using ultraviolet molecular absorption spectrophotometry, and pH was determined using scan image analysis algorithms of pH strips.

RESULTS

A total of 37 phosphate containing glaucoma eye drops were identified. The mean phosphate concentration was 97.72±75.52mM. The group with higher concentration of active substance was timolol (204.85±42.38mM) followed by brimonidine/timolol (200.9mM). No statistically significant difference was found between brand name (95.65±71.11mM) and generic eye drops (99.14±80mM, P=.892). Although no statistically significant difference was found between products containing preservatives (99.24±76.78mM) and those without preservatives (85.17±72.86mM) (P=.730), a lower phosphate concentration was observed in the preservative-free Timolol and Latanoprost. Single dose samples showed a lower phosphate concentration than multi-dose ones (102.04±75.39 vs. 22.24±2.98mM, P<.001). The mean pH was 7.13±0.63. No statistical correlation was found between phosphate concentration and pH (r: 0.07).

CONCLUSION

The phosphate concentration in glaucoma eye drops exceeded the tear film physiological level (1.45mM). No difference was observed between brand names and generic eye drops. Lower phosphate concentration was observed in preservative-free single dose eye drops.

Preservative-free versus preserved latanoprost eye drops in patients with open-angle glaucoma or ocular hypertension

OBJECTIVE

This study compared the efficacy, safety, and pharmacokinetics of a preservative-free latanoprost formulation to an established, benzalkonium chloride (BAK) containing formulation for the treatment of open-angle glaucoma or ocular hypertension.

METHODS

This was a phase II, randomized, cross-over, investigator-masked, multi-center, pilot study (NCT01494753). A total of 30 untreated adult patients (aged ≥18 years) with primary open angle glaucoma, pseudo-exfoliative glaucoma, pigmentary glaucoma, or ocular hypertension received either preservative-free or preserved latanoprost once daily in both eyes for 6 weeks, before crossing over to receive the other treatment. Efficacy (intraocular pressure [IOP] at 8 am, midday, 4 pm and 8 pm, and global efficacy assessment by investigator), safety (adverse events, ocular symptoms and global tolerance, slit lamp examination, funduscopy, visual field examination, visual acuity, and heart rate), and pharmacokinetics were assessed at Days 0, 42, and 84.

RESULTS

Both treatments resulted in a reduction in IOP that was similar for the preservative-free and the preserved formulation at all time points. Similarly, the overall diurnal reduction was similar in both groups (6.3 mmHg [27.9% reduction] and 6.4 mmHg [28.1% reduction] for preserved and preservative-free latanoprost, respectively). There were no differences in global efficacy assessment or in the safety and tolerance of each treatment. Systemic concentrations of latanoprost were very low; AUC0-30 and Cmax were lower and tmax was longer for preservative-free latanoprost.

CONCLUSIONS

Preservative-free latanoprost showed similar efficacy at all time points compared to BAK preservative containing formulation, with no difference in tolerance, allowing progression to phase III clinical development.

A novel rare sugar inhibitor of murine herpes simplex keratitis

Purpose

To determine the therapeutic efficacy of a novel rare sugar, L-psicose, for the treatment of HSV-1 induced herpetic stromal keratitis (HSK) in a mouse eye model.

Methods

One rare sugar L-psicose was assayed for HSV-1 inhibition of in vitro virus adsorption. The IC₅₀ and IC₉₀ values of L-psicose were determined using plaque reduction assay (PRA) in CV-1 cell. Female Balb/c mice were corneally infected with HSV-1, strain KOS-GFP; A topical eye drop treatment of L-psicose was started 24 h after infection and continued four times daily for ten consecutive days. The severity of HSK was monitored by slit lamp examination in a masked fashion and Infectious HSV-1 shedding was determined by PRA.

Results

L-psicose was found to have anti-viral activity in vitro at an IC₅₀ dose of 99.5 mM and an IC₉₀ dose of 160 mM. Topical eye drop treatment with 200 mM L-psicose in PBS solution significantly reduced the severity of HSK compared to the mock treatment group. The in vivo mouse ocular model results of L-psicose therapy correlated with accelerated clearance of virus from eye swabs.

Conclusion

The results suggest that topical treatment with rare sugar L-psicose has efficacy against HSK through inhibition of HSV-1.

Topical delivery of aqueous micellar resolvin E1 analog (RX-10045)

PURPOSE

The primary objective of this study were to optimize aqueous micellar solution of isopropyl ester prodrug of resolvin (RX-10045), study in vivo ocular compatibility and tissue distribution following topical administration.

METHODS

An optimized ratio of hydrogenated castor-oil and octoxynol-40 (1.0:0.05 wt%) was prepared to entrap RX-10045 in the hydrophobic core of micelles. RX-10045 aqueous micelles were subjected to characterization. In vitro stability studies were performed at 4 °C, 25 °C and 40 °C. In vivo studies were conducted in New Zealand albino rabbits following topical drop administration.

RESULTS

Aqueous RX-10045 micellar solutions were successfully prepared. Micelles had a mean diameter of ∼12 nm with low negative surface charge. RX-10045 demonstrated high stability in citrate buffer (0.0 1M) at 40 °C. Hackett-McDonald ocular irritation scores were extremely low comparable to negative control. No significant difference in intraocular pressure was noted. Electroretinography studies did not reveal any retinal damage after multiple dosing of RX-10045 micellar solution. Ocular tissue distribution studies demonstrated appreciable drug concentrations in anterior ocular tissues. Moreover, RX-10008 (active metabolite of RX-10045) was detected in retina/choroid upon topical drop instillation.

CONCLUSIONS

A clear, stable, aqueous 0.1% RX-10045 micellar formulation was successfully prepared. Micellar solution was well-tolerated and did not have any measurable tissue damage in rabbit ocular tissues. Micelles appear to follow conjunctival/scleral pathway to reach back-of-the-eye tissue (retina). Topical aqueous formulations may be employed to treat posterior ocular diseases. Such micellar topical formulations may be more patient acceptable over invasive routes of administrations such as intravitreal injection/implants.

Keratan sulfate: an up-to-date review

Keratan sulfate (KS) is a glycosaminoglycan (GAG) type consisted of a sulfated poly-N-acetyl lactosamine chain. Besides acting as a constitutive molecule of the extracellular matrices, this GAG also plays a role as a hydrating and signaling agent in cornea and cartilage tissues. Inasmuch, KS is widely explored in the pharmaceutical industry. This review will cover the major achievements described in the literature of 2010-2014 concerning this GAG. Discussion about KS' roles in physiopathological conditions, as target or therapeutic molecule in diseases, methods of analysis and detection as well as KS-related enzymes, metabolism and developmental biology is properly provided.

Green nail syndrome treated with the application of tobramycin eye drop

Green nail syndrome (chromonychia) is a nail disorder characterized by onycholysis and green-black discoloration of the nail bed. This condition is often associated with chronic paronychia. Pseudomonas aeruginosa is the most commonly identified organism in cultures from the affected area. Despite the various treatment options available, removal of the nail is still necessary in many cases. A 35-year-old man presented with dark-greenish discoloration of the nail plate and onycholysis on the left thumbnail. He had been treated with oral antifungal and antibiotic agents for several months; however, the lesion showed no improvement. The diagnosis of green nail syndrome was established after a positive bacterial culture, and on the basis of the antibiotic sensitivity test result, tobramycin eye drop (Tobrex®) was then prescribed. Three weeks later, the nail discoloration almost vanished but the onycholysis remained. Herein, we recommend the application of tobramycin eye drop as an easy and safe treatment option for green nail syndrome.

Formulation and stability study of a pediatric 2% phenylephrine hydrochloride eye drop solution

INTRODUCTION

We present formulation and stability evaluation of a 2% (w/v) phenylephrine hydrochloride biocompatible eye drop solution, routinely prepared in hospital pharmacy under aseptic conditions, for retinal examination of neonates and premature infants.

MATERIALS AND METHODS

Eye drop solution was formulated by dissolution of phenylephrine hydrochloride and disodium hydrogen phosphate as buffering agent in sterile water for injection and sodium chloride for injection as isotonic agent. The previous solution was sterile filtered through under aseptic conditions, in an iso class 5 air quality clean room under horizontal laminar airflow hood. Physical stability (visual inspection, osmolality measurements), chemical stability (pH measurement, phenylephrine assay by liquid chromatography coupled with an ultra-high resolution and accurate mass) and sterility evaluation of phenylephrine eye drop solution stored at ambient temperature were studied during 60 days.

RESULTS AND DISCUSSION

The formulated eye drop solution had a pH of 6.90±0.05 and an osmolality of 285±2 mOsm/kg. Throughout the 60 days study the solutions remained clear without any precipitation or color modification, sterility was maintained, pH and osmolality were not significantly modified and no significant loss of product was detected using liquid chromatography coupled with an ultra-high resolution and accurate mass instrument suggesting the lack of degradation.

CONCLUSION

These results indicate that 2% phenylephrine hydrochloride eye drop solutions were physically, chemically and microbiologically stable for at least 60 days when stored in type I amber glass vials at room temperature, allowing the compounding of higher batch sizes.

Locomotor differences in Mongolian gerbils with the effects of midazolam administration in the form of eye drops

BACKGROUND

Midazolam is a sedative-hypnotic agent with amnestic and anticonvulsant properties that can be administrated to mammals through various routes, such as intravenous, intramuscular, oral, intrathecal, rectal, and buccal. Midazolam administration in the form of eye drops through the conjunctiva is not reported in the literature.

AIM

This study aims to demonstrate the possible central nervous system effects of midazolam administration as eyes drops in Mongolian gerbils.

MATERIALS AND METHODS

Fourteen gerbils were randomly assigned to one of two equal sized groups. The active arm received 2 ml of 10 mg midazolam as eye drops in both eyes. Control group received a total of 2 ml of physiological saline (0.9% NaCl). We subjected the gerbils to an adapted "Open Field" to determine the possible effects on central nervous system of midazolam. Gerbils were allowed to move freely in the open field. Before and after the drug administration, locomotor activities of each gerbil have been recorded. Frequency of loss of righting reflex was quantified.

RESULTS

Conjunctival midazolam administration resulted with the transient loss of righting reflex (p=0.017) and suppressed exploration motion (p=0.018) in the open field test compared to control subjects.

CONCLUSIONS

In the present study, administration of conjunctival midazolam as an eye drop may affect gerbil's locomotor activities and open field behaviors. We argue that, using a sedative and anticonvulsive drug such as midazolam via conjunctival route may be useful in some clinical situations. Therefore, it could be beneficial to develop a new conjunctival formulation of midazolam. Also, there is a need for trials in humans with pharmacokinetic studies.