Acute corneal toxicity of latanoprost with different preservatives

Purpose: To investigate the corneal toxicity of Xalatan and three latanoprost generics using transepithelial electrical resistance (TER) and scanning electron microscopy (SEM).

Methods: Corneal TER changes after a 60-s exposure to Xalatan (latanoprost 0.005% preserved with 0.02% BAC), and latanoprost generics (Latanoprost PF BAC free, Latanoprost Nitten SB containing sodium benzoate and Latanoprost Towa containing 0.01% BAC with sodium chloride polysorbate 80 as additive) were measured in living rabbits. Corneal damage was also examined by SEM. Hank’s balanced salt solution (HBSS) was used as a control.

Results: There was a significant decrease in the corneal TER after exposure of the cornea to Xalatan (p?<?0.01) and all latanoprost generics (p?<?0.01: Latanoprost PF, p?<?0.05: Latanoprost Nitten SB, Latanoprost Towa) as compared to HBSS. All latanoprost generics showed less TER decrease in the corneal TER as compared to Xalatan (p?<?0.01). SEM revealed that superficial cells of Xalatan-treated corneas were damaged and exhibited degenerated microvilli. Conversely, the superficial cells of corneas exposed to HBSS or all latanoprost generics appeared normal and had normal microvilli under SEM examinations.

Conclusion: The corneal toxicity of Xalatan is greater than that of latanoprost generics. Xalatan contains 0.02% BAC, which may be responsible for the corneal toxicity.     

Preservative-free versus preserved brimonidine %0.15 preparations in the treatment of glaucoma and ocular hypertension: short term evaluation of efficacy,safety, and potential advantages

Abstract

Purpose: To compare the efficacy, safety, and potential advantages of the preservative-free versus preserved brimonidine %0.15 preparations in patients with primer open-angle glaucoma (POAG) or ocular hypertension (OHT).

Methods: Forty-two eyes of the 21 treatment-naive patients with POAG or OHT were enrolled in this study. Eyes were randomly assigned to receive brimonidine-purite 0.15% or preservative-free brimonidine 0.15% two times daily. Efficacy of the two eye drops was assessed by measuring the intraocular pressure (IOP) at 9–10 am at baseline and week 4. Safety and potential advantages of the drops were evaluated at weeks 4 in terms of ocular symptoms and tear parameters. Ocular symptom values of the patients were evaluated with a scale of 0–4 (0?=?no discomfort and 4?=?severe discomfort).

Results: Both of the brimonidine tartrate formulations resulted in statistically similar IOP reduction (preserved formulation; ?5.2?mmHg [22.9% reduction] preservative-free formulation; ?5.7?mmHg [24.1% reduction], p?=?0.37). It was found that brimonidine tartrate formulations with and without topical preservatives did not produce a statistically significant difference in pain, stinging, and blurred vision at the upon instillation (p?>?0.05). However, the burning sensation was significantly higher in the preservative-free formulation at the first instillation compared to the preserved formulation (p?=?0.01). Also, there was no statistically significant difference between the two formulations in terms of symptoms (itching, burning, tearing, stinging, and photophobia) and tear parameters during the day (p?>?0.05).

Conclusions: Although topical preservative-free brimonidine tartrate treated eyes had a more burning sensation at the first drop, the two formulations were similar in terms of ocular tolerability in the short term period. Also, both formulations were found to reduce IOP at a similar rate.     

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; AUC_0–30 and C_max were lower and t_max 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.     

Castor oil and mineral oil nanoemulsion: development and compatibility with a soft contact lens

Abstract

Context: The non-invasive ophthalmic therapy has a drawback: low residence time in the eye socket. Nanoparticles and contact lenses have been studied as promising ocular drug delivery systems.

Objective: To develop a nanoemulsion and evaluate its compatibility with a soft contact lens as a potential strategy for ocular delivery.

Materials and methods: The formulations were developed by spontaneous emulsification and fully characterized. Two drops of nanoemulsion were instilled on the surface of a commercial contact lens and its transparency was measured using a UV-Vis spectrophotometer. Before and after the instillation of the drops, the morphology (scanning electron microscopy – SEM) and ion permeability of the lenses were analyzed.

Results: The formulations had a mean particle size of 234?nm, polydispersity below 0.16, zeta potential of ?8.56?±?3.49?mV, slightly acid pH, viscosity ≈1.2?mPa?s^?1 and spherical-shaped particles. Nanoemulsion was non-irritant (hen’s egg test-chorioallantoic membrane), which was confirmed by the cytotoxicity studies in the SIRC cell cultures. After instillation, SEM analysis showed nanodroplets inside and on the surface of the lenses, although their transparency remained near 100%. No significant differences were found between lens ion permeability coefficients before and after instillation.

Conclusions: Formulations presented appropriate physicochemical characteristics and suitability for ocular application. The contact lens remained transparent and ion-permeable after association with the formulation.     

Brimonidine purite 0.1% versus brinzolamide 1% as adjunctive therapy to latanoprost in patients with glaucoma or ocular hypertension

ABSTRACT

Objective: To evaluate the efficacy and tolerability of brimonidine purite 0.1% in comparison to brinzolamide 1% when used as adjunctive therapy to latanoprost 0.005% in patients with glaucoma or ocular hypertension.

Methods: Randomized, single-center, investigator-masked, parallel-group clinical study. Patients with IOP?≥?18?mmHg while on once-daily latanoprost were randomized to adjunctive treatment with brimonidine purite TID (n?=?20) or brinzolamide TID (n?=?20) for 3 months. Intraocular pressure (IOP) was measured at 8 a.m., 10 a.m., and 4 p.m. at latanoprost-treated baseline and after 1 and 3 months of latanoprost and adjunctive therapy. A patient questionnaire was administered to evaluate the tolerability of eye drop instillation.

Results: Baseline mean diurnal IOP (± standard deviation, mmHg) on latanoprost was comparable between groups (brimonidine purite: 19.6?±?2.94; brinzolamide: 19.8?±?3.25; p = 0.846). Mean diurnal IOP at Month 3 was 16.3?±?2.63?mmHg with brimonidine purite and 17.8?±?2.19?mmHg with brinzolamide (?p = 0.028). Adjunctive use of brimonidine purite provided greater IOP lowering than brinzolamide at 10 a.m. (?p < 0.001) and 4 p.m. (?p = 0.050) and equivalent IOP lowering to brinzolamide at 8 a.m. (?p = 0.716). Blurred vision at Month 1 and bitter taste at Months 1 and 3 were more common upon instillation of brinzolamide eye drops.

Conclusion: Brimonidine purite 0.1% provided significantly lower IOP compared with brinzolamide 1% when used as adjunctive therapy to latanoprost. Both adjunctive therapies were well tolerated. Limitations of this study include the use of a single site and the sample size. Additional studies are needed to further evaluate these drugs as adjunctive therapy to prostaglandin analogs.     

Calculation of AQCmax: comparison of five ophthalmic fluoroquinolone solutions

ABSTRACT

Objective: Ocular tissue penetration of five different ophthalmic fluoroquinolone solutions in the rabbit eye was measured and evaluated by an index of the maximum aqueous concentration (AQCmax).

Methods: Moxifloxacin 0.5% (MFLX), levofloxacin 0.5% (LVFX), gatifloxacin 0.3% (GFLX), ofloxacin 0.3% (OFLX), or tosufloxacin tosilate 0.3% (TFLX) were instilled into the eyes of white rabbits every 15?min for a total of three doses. Aqueous humor, cornea, iris/ciliary body and vitreous body were collected 10 to 240?min after instillation and drug concentrations were measured by high-performance liquid chromatography.

Results: The concentration of MFLX was the highest in each tissue, with maximum concentrations of MFLX in the aqueous humor (10.16?±?1.59?µg/mL) at 30?min after instillation, cornea (156.07?±?95.97?µg/g) and iris/ciliary body (11.92?±?4.00?µg/g) at 10?min after instillation, and vitreous body (0.099?±?0.033?µg/mL) at 30?min after instillation. The concentration of TFLX was the lowest in each tissue, with LVFX, GFLX, and OFLX sharing the mid-ranks. AQCmax?:?MIC₉₀ ratio for S.?aureus was 150.67 for MFLX, 10.6 for LVFX, 9.69 for GFLX, 3.48 for OFLX, and could not be determined for TFLX.

Conclusion: AQCmax is a useful pharmacokinetic parameter for determining the therapeutic efficacy of an ophthalmic antibiotic, especially when combined with MIC₉₀ values for intraocular pathogens. C_max of MFLX ophthalmic solution was superior in all tissues (cornea, aqueous humor, iris/ciliary body and vitreous body) among the five ophthalmic solutions studied, exceeding the MIC₉₀ of S.?aureus in all tissues, and MIC₉₀s of S.?epidermidis, B.?cereus, and P.?acnes in aqueous humor, cornea, and iris/ciliary body. AQCmax was approximately proportional to C_max in iris/ciliary body and vitreous, and may be used in combination with MIC₉₀s as an index to predict the most appropriate dose and frequency of ophthalmic antibiotics in conjunction with other PK/PD parameters. This study may provide the groundwork for calculation of AQCmax in humans.     

Safety of sodium hyaluronate eye drop with C12-benzalkonium chloride

Purpose: In this study, we investigated the effects of commercially available multi-dose sodium hyaluronate 0.1% (Hyalein^®; Santen, Osaka, Japan) containing 0.003% C12-benzalkonium chloride (BAC) on the Corneal epithelium and its degree of safety.

Methods: Japanese white male rabbits were divided into four groups. The corneas of each group exposed to one of the following solutions: sodium hyaluronate 0.1%, C12-BAC, C12, 14, 16-BAC Mixture, and Hank’s Balanced Salt Solution (HBSS) (as control), respectively. Corneal transepithelial electrical resistance (TER) changes after 60?s of exposure to the above solutions were measured in living rabbits. TER reflects the barrier function of the epithelium. In addition, scanning electron microscopy was used to examine the acute effects of the above solutions on the integrity of the corneal epithelium of four groups.

Results: There was no significant decrease in the corneal TER after exposure of the cornea to Hyalein^® eye drops as compared to HBSS control eyes. Also, BAC mixture solution and C12-BAC did not produce any significant decrease in the corneal TER as compared to HBSS control eyes. All the corneal epithelium exposed to Hyalein^®, 0.003% C12-BAC and 0.003% BAC mixture exhibited a regular appearance of the superficial cells with a high density of microvilli.

Conclusion: This study confirms that Hyalein^® has no acute hazardous effect on corneal epithelium.     

Sustained ophthalmic in situ gel of ketorolac tromethamine: rheology and in vivo studies

Most ocular diseases are treated with topical eye drops. The poor bioavailability and therapeutic response exhibited by these conventional eye drops due to rapid precorneal elimination of the drug may be overcome by the use of in situ gelling systems that are instilled as drops into the eye and undergo a sol‐to‐gel transition in the cul‐de‐sac. The present work describes the formulation and evaluation of an ophthalmic delivery system of the nonsteroidal anti‐inflammatory drug (NSAID), ketorolac tromethamine, based on the concept of pH‐triggered in situ gelation. Polyacrylic acid (Carbopol^® 934) was used as the gelling agent in combination with hydroxypropylmethylcellulose (Methocel E15LV), which acted as a viscosity enhancer. The prepared formulations were characterized for clarity, pH, drug content, rheology, and in vivo drug release. Clarity, pH, and drug content of the developed formulations were found to be satisfactory. The developed formulation showed pseudo‐plastic rheology. The formulation with benzalkonium chloride and edetate disodium improved the rate of corneal absorption but not the extent. The developed formulation is a viable alternative to conventional eye drops by virtue of its ability to enhance bioavailability through its longer precorneal residence time and ability to sustain drug release. Also importantly is the ease of instillation afforded and decreased frequency of instillation resulting in better patient acceptance. Drug Dev Res, 2009. © 2009 Wiley‐Liss, Inc.     

Novel Topical Ophthalmic Formulations for Management of Glaucoma

Purpose

Preparation of topical ophthalmic formulations containing brimonidine-loaded nanoparticles prepared from various biodegradable polymers—PCL, PLA and PLGA—for sustained release of brimonidine as a once daily regimen for management of glaucoma.

Methods

Nanoparticles were prepared using spontaneous emulsification solvent diffusion method then characterized regarding their particle size, zeta potential, morphology and drug contents. Brimonidine-loaded nanoparticles were incorporated into eye drops, temperature-triggered in situ gelling system and preformed gel and characterized regarding their pH, viscosity, uniformity of drug contents, in vitro release study, in vitro cytotoxicity and in vivo intraocular pressure (IOP) lowering effects.

Results

The results of optimized brimonidine-loaded PCL-, PLGA- and PLA-NPs respectively, are: particle sizes of 117.33?±?4.58 nm, 125.67?±?5.15 nm and 131.67?±?3.79 nm; zeta potentials of ?18.5?±?2.87 mV, ?21.82?±?2.7 mV and ?28.11?±?2.21 mV; and encapsulation efficiencies of 77.97?±?1.38%, 68.65?±?3.35% and 73.52?±?2.92%. TEM analyses revealed that all NPs have spherical shapes with dense core and distinct coat. In vitro release data showed a sustained release without any burst effect with Higuchi non-Fickian diffusion mechanism. Cytotoxicity studies revealed that all formulations are non-toxic. Also all formulations possessed a sustained IOP lowering effect compared to Alphagan® P eye drops.

Conclusions

Our formulations showed prolonged management of glaucoma that should meet with better patient compliance as a once-daily formulation.     

N-hydroxymethylglycinate with EDTA is an efficient eye drop preservative with very low toxicity: an in vitro comparative study

Purpose: Preservatives are used in multi-dose ophthalmic topical medications in order to prevent contamination by bacteria and fungi. However, prolonged use of preserved eye drops, as it may happen in dry eye or glaucoma, may damage cells of the ocular surface. Therefore, an important goal is to find preservatives with low toxicity which are mild to host cells, still able to prevent drug contamination so to maintain their sterility and efficacy. Hence, aim of this study has been to compare the relative toxicity on a rabbit corneal cell line of a new preservative, made by the association of N-hydroxy-methyl-glycinate (NIG) with disodium-ethylene diamine tetra-acetate (EDTA), with other known and widely used eye-drops preservatives.

Materials and methods: Rabbit corneal cells (SIRC) were tested either in 96-well plates or in suspension culture. Treatments with preservatives (used at known bacteriostatic concentrations) included: benzalkonium chloride (BAK), polyquaternium-1 (PQ-1), sodium perborate (SP: NaBO_{3 *} H₂O), and NIG?±?EDTA at different concentrations (0.001% and 0.002%), and different treatment times (from 30?minutes to 120?hours). At the end of treatment, cell survival was evaluated by a specific spectrophotometric method through the metabolic conversion of MTT [3-(4,5-dimethylthiazol-2-yl) 2, 5-diphenyltetrazolium bromide] into formazan crystals.

Results: Almost no cell toxicity was evident for NIG and SP at either concentration (0.001% or 0.002%), while a low toxicity was observed for PQ-1 (62% at the highest dose at 120?hours). BAK, as expected, showed the highest toxicity (60–80% at 30?minutes, and over 90% from eight hours onward). EDTA 0.1% alone or in combination with NIG 0.002%, showed no toxicity at 24?hours, and even resulted in cell growth promotion (46% and 38%, respectively), after 48?hours of treatment.

Conclusions: These data show that the new preservative NIG/EDTA, at doses known to have effective antimicrobial properties, has a very low toxicity on corneal cells, and so it can be safely used in multi-dose eye drops.     

Effect of mydriasis induced by topical 0.5% tropicamide instillation on the corneal biomechanical properties in healthy individuals measured by ocular response analyzer

Purpose: This observational study aims to investigate the effects of tropicamide (0.5%) on corneal biomechanical properties, with the ocular response analyzer (ORA), in healthy individuals.

Methods: Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) measurements of 38 (21 female and 17 male) healthy individuals, before and after 30?min of 0.5% tropicamide instillation, were performed by using the ORA.

Results: The mean CH, CRF, IOPg and IOPcc measurements of the eyes were 10.2?±?1.9?mmHg, 10.3?±?2.1?mmHg, 15.7?±?3.4?mmHg, 16.4?±?3.3?mmHg pre-tropicamide, and 10.4?±?1.7?mmHg, 10.3?±?2.1?mmHg, 15.3?±?3.4?mmHg, 15.8?±?2.7?mmHg post-tropicamide, respectively. The differences between the pre- and post-tropicamide measurements of the eyes were insignificant (p?=?0.184, p?=?0.659, p?=?0.294, p?=?0.150, respectively; paired t-test).

Conclusions: A tropicamide instillation does not lead to significant changes in the corneal biomechanical properties. Therefore, it can be used safely in disease, i.e. in the diagnosis and follow-up ORA as it does not cause any change.     

Latanoprost: new preparation. Antiglaucoma eye drops that can change the colour of the iris

(1) Latanoprost, a prostaglandin F2 alpha analogue, is an antiglaucoma drug. (2) The clinical file is fairly thorough. (3) Dose-finding studies show that the optimal daily dose is a single drop of 0.005% solution, preferably in the evening. Two drops a day are less effective than one drop a day. (4) The local hypotensive action of latanoprost persists in the long term (current follow-up one year). (5) Four double-blind trials have compared 0.005% latanoprost eye drops and 0.5% timolol eye drops. In three trials the effect of latanoprost on intraocular pressure was statistically stronger than that of timolol. However, the difference in mean intraocular pressure was less than 2 mm Hg between the two treatments, and the clinical relevance of such a difference is not known. (6) Latanoprost has not been compared with the other available antiglaucoma eye drops. (7) Various trials have shown that intraocular pressure is statistically lower when latanoprost is combined with another antiglaucoma eye drop preparation (timolol, pilocarpine or dipivefrine) than during monotherapy. The additive action of latanoprost eye drops when combined with oral acetazolamide has been established more soundly in a comparative double-blind trial. (8) In approximately 30% of cases (especially patients with non homogeneous eye colour), latanoprost eye drops can cause permanent darkening of the iris. Patients must be warned of this risk before beginning treatment.     

BCOP法评价滴眼液的角膜渗透性

目的 采用牛角膜混浊和渗透性试验（bovine corneal opacity and permeability,BCOP）方法对滴眼液的角膜渗透性进行评价。方法 利用BCOP法,以无酚红MEM培养液为介质,前室加滴眼液样品,于不同时间点后室取样,用紫外-可见分光光度法测定其苄达赖氨酸的含量,比较不同滴眼液样品的角膜渗透性。结果 不同厂家样品表现出不同的角膜渗透性,包括角膜累积渗透量、透过速率、表观渗透系数和稳态渗透速率均不同。结论 可用BCOP法进行眼用制剂的角膜渗透性研究。     

Intraoperative corneal thickness measurements during corneal collagen cross-linking with isotonic riboflavin solution without dextran in corneal ectasia

Objective: To monitor the changes in corneal thickness during the corneal collagen cross-linking procedure by using isotonic riboflavin solution without dextran in ectatic corneal diseases.

Materials and Methods: The corneal thickness measurements were obtained before epithelial removal, after epithelial removal, following the instillation of isotonic riboflavin solution without dextran for 30?min, and after 10?min of ultraviolet A irradiation.

Results: Eleven eyes of eleven patients with progressive keratoconus (n?=?10) and iatrogenic corneal ectasia (n?=?1) were included in this study. The mean thinnest pachymetric measurements were 391.82?±?30.34?µm (320–434?µm) after de-epithelialization of the cornea, 435?±?21.17?µm (402–472?µm) following 30?min instillation of isotonic riboflavin solution without dextran and 431.73?±?20.64?µm (387–461?µm) following 10?min of ultraviolet A irradiation to the cornea.

Conclusion: Performing corneal cross-linking procedure with isotonic riboflavin solution without dextran might not induce corneal thinning but a little swelling throughout the procedure.     

Fabrication and evaluation of lipid nanoparticulates for ocular delivery of a COX-2 inhibitor

Context: The unique physiological limitations of the eye have been assigned as reason of low bioavailability by conventional drug delivery systems. There is need of such drug carriers, which ensure improved bioavailability as well as patient compliance upon instillation into the eye.

Objective: The present investigation deals with development of solid lipid nanoparticles (SLNs) containing celecoxib (CXB) for treatment of ophthalmic inflammations.

Materials and methods: The SLNs were formulated by melt-emulsion sonication and low temperature-solidification process and evaluated for particle size, surface morphology, physicochemical properties, percentage drug incorporation efficiency, in vitro drug release, in vitro trans-corneal permeation, in vivo efficacy in ocular inflammation, stability study and gamma scintigraphy study to assess the residence of solid lipid nanoparticles over ocular surfaces.

Results: The SLNs were spherical and the optimized formulation had particle size of 198.77?±?7.5?nm, which is quite suitable for ocular applications. The maximum entrapment efficiency of 92.46?±?0.07% was achieved for formulation SLN 20. The permeation across the cornea was also significantly better than aqueous suspension (8.21?±?0.67 versus 4.61?±?0.71) at p?<?0.05.

Discussion and conclusion: The SLN formulations demonstrated improved performance of entrapped CXB while mitigating the key parameters of ocular inflammation in rabbits. The particulate formulations have exhibited prolonged retention over ocular surfaces as evident from results of gamma scintigraphy using ^99mTc labeled SLNs.     

Comparison of morning versus evening dosing and 24-h post-dose efficacy of travoprost compared with latanoprost in patients with open-angle glaucoma

ABSTRACT

Objective: To compare the IOP-lowering efficacy of a.m.-dosed travoprost and latanoprost at 24-h post-dose.

Research design and methods: Open-angle glaucoma patients not naïve to prostaglandin therapy and currently controlled on p.m.-dosed (2100) latanoprost (n?=?21) or travoprost (n?=?30) had baseline IOPs measured at 0900. In a randomized, single-masked, crossover design, patients received travoprost (Travatan) or latanoprost (Xalatan) at 0900 for 4?weeks, then were crossed over to receive the second prostaglandin for another 4?weeks. Treatment IOP was measured at 0900 prior to morning dose at both 4 and 8?week visits. Patient dosing preference (a.m./p.m.) was surveyed on exit.

Main outcome measure: Intraocular pressure (IOP).

Results: The mean IOP in the first period when all patients were dosed in the evening was assessed 12?h after dosing at 09:00 and it was similar in the two treatment groups (mean?±?standard deviation: 17.9?±?2.7?mmHg for travoprost versus 17.7?±?2.5?mmHg for latanoprost, p?=?0.812). In the a.m.-dosing crossover comparison, the 24-h post-dose IOP was significantly lower (?p?<?0.001) on travoprost (16.9?±?3.1?mmHg) compared to latanoprost (18.6?±?3.3?mmHg). In the exit survey, 51% of patients preferred a.m.-dosing.

Conclusions: a.m.-dosed travoprost is superior to a.m.-dosed latanoprost by 1.7?mmHg at 24-h post-dose.     

The ocular surface side effects of an anti-psychotic drug,clozapine

Purpose: The purpose of this study is to investigate the effects of long-term clozapine usage on tear film stability and corneal topographic parameters.

Material and methods: The study was conducted between March 2014 and November 2014. Thirty patients who were diagnosed of schizophrenia and have been under clozapine treatment for 2.73?±?0.73 years (range 2–4 years) were involved in this study (group 1). Thirty healthy subjects (group 2) who have statistically similar demographic features compared with the group 1, were involved as a control group. Full ophthalmologic examination with biomicroscopy and indirect ophthalmoscopy was applied. Corneal topographic parameters were measured using the Pentacam HR and Schirmer test was done. Statistical analysis of the subjects was evaluated by using SPSS (for Windows version 16.0; SPSS Inc., Chicago, IL) program.

Results: K₁ value was measured as 43.39?±?0.17?D (43–43.50?D) and K₂ value was measured as 43.39?±?0.06?D (43.30–43.50?D) in groups 1 and 2, respectively. In groups 1 and 2, K₂ values were noted as 43.86?±?0.27?D (43.50–44.50?D) and 43.72?±?0.18?D (43.50–44.00?D), respectively. Central corneal thickness was found to be 523.93?±?15.66?µm (495–554?µm) and 550.13?±?1.03?µm (520–580?µm) in groups 1 and 2, respectively. Corneal apex thickness was 525.86?±?15.75?µm (497–556?µm) in group 1 and 551.60?±?14.99?µm (521–581?µm) in group 2. The corneal thickness of thinnest location was 520.93?±?15.60?µm (492–551?µm) and 548.06?±?15.17?µm (518–578?µm) in groups 1 and 2, respectively. Corneal volume was determined as 58.13?±?3.46?mm³ (52–64?mm³) in group 1 and 60.73?±?3.76?mm³ (54–66?mm³) in group 2. The Schirmer test showed thichkness of 3.33?±?0.72?mm (2–4?mm) and 13.60?±?1.59?mm (11–16?mm) in groups 1 and 2, respectively. The mean fluorescein break-up time was 5.40?±?1.50?s (3–8?s) and 12.46?±?1.40?s (10–14?s) in groups 1 and 2, respectively. There was a statistically significant difference in the Schirmer test, fluorescein break-up time, central corneal thickness, corneal apex, and the thinnest corneal location thickness between the two groups.

Conclusion: Clozapine may induce dry eye syndrome and thus may lead to morphological alterations in corneal parameters through its anticholinergic and antidopaminergic activities. Because of these corneal alterations, one should be aware of evaluating patients having diseases like glaucoma or preoperative selection of corneal refractive surgery candidates.     

Estimate of safe human exposure levels for lunar dust based on comparative benchmark dose modeling

Abstract

Brief exposures of Apollo astronauts to lunar dust occasionally elicited upper respiratory irritation; however, no limits were ever set for prolonged exposure to lunar dust. The United States and other space faring nations intend to return to the moon for extensive exploration within a few decades. In the meantime, habitats for that exploration, whether mobile or fixed, must be designed to limit human exposure to lunar dust to safe levels. Herein we estimate safe exposure limits for lunar dust collected during the Apollo 14 mission. We instilled three respirable-sized (～2 μ mass median diameter) lunar dusts (two ground and one unground) and two standard dusts of widely different toxicities (quartz and TiO₂) into the respiratory system of rats. Rats in groups of six were given 0, 1, 2.5 or 7.5?mg of the test dust in a saline-Survanta® vehicle, and biochemical and cellular biomarkers of toxicity in lung lavage fluid were assayed 1 week and one month after instillation. By comparing the dose--response curves of sensitive biomarkers, we estimated safe exposure levels for astronauts and concluded that unground lunar dust and dust ground by two different methods were not toxicologically distinguishable. The safe exposure estimates were 1.3?±?0.4?mg/m³ (jet-milled dust), 1.0?±?0.5?mg/m³ (ball-milled dust) and 0.9?±?0.3?mg/m³ (unground, natural dust). We estimate that 0.5–1?mg/m³ of lunar dust is safe for periodic human exposures during long stays in habitats on the lunar surface.     

Circadian IOP-lowering efficacy of travoprost 0.004% ophthalmic solution compared to latanoprost 0.005%*

ABSTRACT

Purpose: The primary objective of this study was to determine the intraocular pressure- (IOP) lowering efficacy over two consecutive 24-h periods of travoprost 0.004% ophthalmic solution (Travatan^?) compared to latanoprost 0.005% (Xalatan^?) dosed once daily in patients with primary open-angle glaucoma or ocular hypertension.

Methods: This was a double-masked trial conducted at the Hospital Clínico San Carlos, Madrid, Spain. The primary objective of this study was to determine the IOP lowering efficacy of travoprost and latanoprost. During the eligibility visit, patients’ IOP was measured throughout two consecutive 24‐h periods every 4?h. Patients were then randomized to travoprost or latanoprost (one drop at 8 p.m. daily for 2 weeks). Sixty-two patients were randomized (travoprost n = 32; latanoprost n = 30). IOP was measured at week 2 every 4?h throughout two 24‐h periods. All measurements were taken in both supine and sitting positions with the aid of Perkins applanation tonometry. Limitations of the study include a small sample size (due to the difficulty in recruiting patients in a study of this type) which enrolled only Caucasian patients and a short study duration. However, with 25 subjects per group, there was at least 90% power to detect a mean IOP change from baseline of 2.9?mmHg and 80% power to detect a difference of 2.5?mmHg between treatments.

Results: Patients on travoprost therapy showed lower mean IOP levels than those on latanoprost. This difference was statistically significant (?p < 0.05) at 12, 16, 20, 24, 36, 40, and 48?h after the last dose for the supine position. The mean IOPs in the supine position throughout the first and the second 24‐h period of the week 2 visit as well as for the 48‐h visit were statistically lower (?p < 0.05) for the travoprost group. Adverse events were mild and included hyperemia and corneal staining. Travoprost and latanoprost were both well tolerated.

Conclusion: Mean IOP values were significantly lower for patients on travoprost for the majority of time points in the supine position.     

Effect of fluoroquinolones on the expression of matrix metalloproteinase in debrided cornea of rats

Matrix metalloproteinases (MMPs) are implicated in regenerative and healing processes in corneal injuries. Based upon reports that topical fluoroquinolones (FQs) may cause perforations during corneal healing by modulating MMPs, this study evaluated the comparative effects of commercially available FQs eye drops on the expression of MMP-2 and MMP-9 in the cornea after ethanol injury. Uniform corneal epithelial defects were created using 70% ethanol in the right eye of the rats (n?=?6). The groups studied were (I) sham, (II) normal saline with benzalkonium chloride (NS-BKC), (III) norfloxacin 0.3%, (IV) ciprofloxacin 0.3%, (V) lomefloxacin 0.3%, (VI) sparfloxacin 0.3%, (VII) gatifloxacin 0.3%, and (VIII) moxifloxacin 0.5%. Each treatment was instilled six times/day up to 48?h and rats were sacrificed using excess of anesthesia. The corneas were excised to study the expression of MMP-2 and MMP-9 using gelatin zymography and real-time PCR. All the FQs significantly increased the expression of MMP-2 and MMP-9 as compared to the sham and NS-BKC-treated group. NS-BKC did not show a significant effect on MMPs expression compared to the sham group. Among the studied FQs, ciprofloxacin was observed to exhibit maximal induction of MMP-2 and MMP-9, whereas lomefloxacin exhibited an equivocal effect on both MMP-2 and MMP-9 expression. Findings of the present study demonstrate that topical application of FQs may induce the expression of MMP-2 and MMP-9 in debrided corneal epithelium and, therefore, may delay corneal wound healing. Thus, it can be concluded that selecting a FQ for ophthalmic use having minimal effect on MMPs may impact wound healing in injured or vulnerable cornea.