Ocular Tolerance Research Articles

Intraocular pressure-lowering effects of commonly used fixed combination drugs with timolol in the management of primary open angle glaucoma.

To evaluate intraocular pressure (IOP)-lowering effect and ocular tolerability of brimonidine/timolol, dorzolamide/timolol and latanoprost/timolol fixed combination therapies in the management of primary open angle glaucoma. Each drug was administered for two months, after which a circadian tonometric curve was recorded using a Goldmann applanation tonometer. Ocular discomfort (conjunctival hyperemia, burning or stinging, foreign body sensation, itching, ocular pain) of each eye was assessed by the subject on a standardized ocular discomfort scale. Among the three study groups, there were no significant differences in the mean baseline IOP measurements, mean 2(nd) mo IOP measurements, and mean (%) change of IOPs from baseline. Among the three study groups, there were no significant differences in the mean IOP measurements obtained at circadian tonometric curves at baseline and at two months controls. In sum brimonidine/timolol, dorzolamide/timolol and latanoprost/timolol fixed combination therapies showed similar effects on IOP levels. Brimonidine/timolol, dorzolamide/timolol and latanoprost/timolol fixed combination therapies showed similar lowering efficaties on IOP levels whereas there was no any difference between each other.

Recent patents on ophthalmic nanoformulations and therapeutic implications.

Nanoformulations (NF) are widely explored as potential alternatives for traditional ophthalmic formulation approaches. The effective treatment of ocular diseases using conventional eye drops is often hampered by factors such as: physiological barriers, rapid elimination, protein binding, and enzymatic drug degradation. Combined, these factors are known to contribute to reduced ocular residence time and poor bioavailability. Recent research studies demonstrated that NF can significantly enhance the therapeutic efficacy and bioavailability of ocular drugs, compared to the established ophthalmic drug delivery strategies. The research studies resulted in a number of patent inventions, reporting a significant increase in therapeutic efficacy for various chronic ocular disease states of both the anterior and posterior ocular segments. This article reviews these patent disclosures in detail and emphasizes the therapeutic advantages conferred by the following nanoformulation approaches: Calcium Phosphate (CaP) nanoparticles, Liposomes, Nanoemulsions, Nanomicelles, and Hydrogels. The nanoformulation approaches were shown to enhance the ocular bioavailability by reducing the drugprotein binding, increasing the corneal resident time, enhancing the drug permeability and providing a sustained drug release. Further, the article discusses United States Food and Drug Administration (USFDA) approved ocular drugs employing nanotechnology and future developments. It should be noted that, despite the potential therapeutic promise demonstrated by nanotechnology for ocular drug delivery, the bench to bed transition from patent inventions to marketed drug products has been insignificant. Majority of the discussed technologies are still in development and testing phase for commercial viability. Further, studies are in progress to assess ocular tolerance and nanotoxicity for prolonged use of NF.

Preclinical pharmacology, ocular tolerability and ocular hypotensive efficacy of a novel non-peptide bradykinin mimetic small molecule

We sought to characterize the ocular pharmacology, tolerability and intraocular pressure (IOP)-lowering efficacy of FR-190997, a non-peptidic bradykinin (BK) B2-receptor agonist. FR-190997 possessed a relatively high receptor binding affinity (Ki = 27 nM) and a high in vitro potency (EC50 = 18.3 ± 4.4 nM) for inositol-1-phosphate generation via human cloned B2-receptors expressed in host cells with mimimal activity at B1-receptors. It also mobilized intracellular Ca2+ in isolated human trabecular meshwork (h-TM), ciliary muscle (h-CM), and in immortalized non-pigmented ciliary epithelial (h-iNPE) cells (EC50s = 167–384 nM; Emax = 32–86% of BK-induced response). HOE-140, a selective B2-receptor antagonist, potently blocked the latter effects of FR-190997 (e.g. IC50 = 7.3 ± 0.6 nM in h-CM cells). FR-190997 also stimulated the release of prostaglandins (PGs) from h-TM and h-CM cells (EC50s = 60–84 nM; Emax = 29–44% relative to max. BK-induced effects). FR-190997 (0.3–300 μg t.o.) did not activate cat corneal polymodal nociceptors and did not cause ocular discomfort in Dutch-Belted rabbits, but it was not well tolerated in New Zealand albino rabbits and Hartley guinea pigs. A single topical ocular (t.o.) dose of 1% FR-190997 in Dutch-Belted rabbits and mixed breed cats did not lower IOP. However, FR-190997 efficaciously lowered IOP of conscious ocular hypertensive cynomolgus monkey eyes (e.g. 34.5 ± 7.5% decrease; 6 h post-dose of 30 μg t.o.; n = 8). Thus, FR-190997 is an unexampled efficacious ocular hypotensive B2-receptor non-peptide BK agonist that activates multiple signaling pathways to cause IOP reduction.

Design of Nanosuspensions and Freeze-Dried PLGA Nanoparticles as a Novel Approach for Ophthalmic Delivery of Pranoprofen

Pranoprofen (PF)-loaded poly (lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) were optimized and characterized as a means of exploring novel formulations to improve the biopharmaceutical profile of this drug. These systems were prepared using the solvent displacement technique, with polyvinyl alcohol (PVA) as a stabilizer. A factorial design was applied to study the influence of several factors (the pH of the aqueous phase and the stabilizer, polymer and drug concentrations) on the physicochemical properties of the NPs. After optimization, the study was performed at two different aqueous phase pH values (4.50 and 5.50), two concentrations of PF (1.00 and 1.50 mg/mL), three of PVA (5, 10, and 25 mg/mL), and two of PLGA (9.00 and 9.50 mg/mL). These conditions produced NPs of a size appropriate particle size for ocular administration (around 350 nm) and high entrapment efficiency (80%). To improve their stability, the optimized NPs were lyophilized. X-ray, FTIR, and differential scanning calorimetry analysis confirmed the drug was dispersed inside the particles. The release profiles of PF from the primary nanosuspensions and rehydrated freeze-dried NPs were similar and exhibited a sustained drug delivery pattern. The ocular tolerance was assessed by an HET-CAM test. No signs of ocular irritancy were detected (score 0).

English

PURPOSE: To compare IOP(intraocular pressure) lowering efficacy and ocular tolerability of dorzolamide 2% thrice daily and brinzolamide 1% twice daily, for three months, in a North-Indian population. METHODS: A prospective, randomized comparison in which 100 eyes of 50 subjects received dorzolamide 2% thrice daily or brinzolamide 1% twice daily for 3 months. Intraocular pressure diurnal variation, visual analogue pain/discomfort score, central corneal thickness and ocular and systemic symptom queries were completed at baseline, 3 weeks, and 3 months. RESULTS: Both agents produced clinically and statistically significant (P <.001) decreases in IOP. Mean intraocular pressure changes after brinzolamide 1% twice daily (-3.4 to -5.8 mm Hg reduction of mean IOPs by time of day) were statistically equivalent (confidence limit <1.5 mm Hg) to dorzolamide 2% three times a day (-3.9 to -5.6 mm Hg reduction of mean IOPs by time of day). The incidence of chronic ocular discomfort (burning and stinging) on instillation of brinzolamide was 8% compared to 28% on treatment with dorzolamide. Immediate visual analogue scores were also significantly higher (P <0.005) among patients receiving dorzolamide compared to brinzolamide. CONCLUSIONS: Both Brinzolamide 1.0% twice daily and Dorzolamide 2% thrice daily produced clinically relevant and statistically significant IOP reductions, and were statistically equivalent when compared. Brinzolamide produced significantly less ocular discomfort (burning and stinging) both immediately on instillation and on chronic use compared to Dorzolamide. This, combined with the twice daily dosing, can help improve compliance among patients.

Ocular tolerability and efficacy of a cationic emulsion in patients with mild to moderate dry eye disease – A randomised comparative study

The purpose of this study was to compare the safety and efficacy of a new cationic emulsion (CE) with a formulation of polyvinyl alcohol and povidone (PVA-P) for the treatment of mild to moderate dry eye disease. This was a multicenter, open-label, comparative study. Patients were randomised to receive CE (Cationorm) or PVA-P (Refresh) (1:1). The following objective criteria were assessed to compare the two eye drops: tear Break-up Time (TBUT), Schirmer's test, lissamine green staining (Van Bijsterveld score), corneal fluorescein staining (Oxford scale) and oculopalpebral examination, on D7 and D28 (end of study). At these visits, ocular symptoms and safety were also assessed. Seventy-nine patients were randomised: CE: 44 patients; PVA-P: 35 patients. At D28, improvement was significantly better for TBUT [CE: 1.7 ± 2.4 s; PVA-P: 0.6 ± 1.8 s; P=0.015] and for the Van Bijsterveld score [CE: -1.4 ± 1.2; PVA-P: -0.9 ± 1.2; P=0.046] in the CE group. The same applied for the palpebral erythema score (P=0.023), overall efficacy assessed by the investigators (P<0.001), and symptoms not related to eye drop instillation (P=0.021). Improvement was observed from D7. No difference was observed between the two treatments with regard to ocular safety. These results suggest that in patients with mild to moderate dry eye, Cationorm, in addition to its moisturizing and lubricating properties, also helps stabilize the tear film due to its oily component. This study demonstrates the benefit of this new pharmaceutical form for the treatment of mild to moderate dry eye disease.

Functional Tumor Necrosis Factor Alpha Polymorphisms and Haplotype Analysis in High-Risk Corneal Transplantation

BackgroundTumor necrosis factor alpha (TNF-α) plays a critical role in diverse cellular processes including ocular immune tolerance, inflammation, and allograft rejection. The ubiquitous transcription factor nuclear factor kappa B (NF-κB) regulates expression of numerous genes. Induction of the TNF-α pathway is involved in the inflammatory response and loss of transplant tolerance. ObjectivesWe investigated functional single nucleotide polymorphisms (SNPs) in the promoter region of TNF-α and an insertion/deletion (indel) polymorphism of NF-κB1 in corneal transplant recipients considered to be at increased risk of immunological rejection (ie, high-risk corneal transplantations) and looked for any associations with corneal transplantation outcome. Patients and MethodsThree hundred eighty-four full thickness corneal transplant recipients were followed for 3 years and episodes of reversible and irreversible allograft rejection were recorded. Using DNA obtained from these patients, 5 SNPs located in the promoter region −1031 T/C rs1799964, −863 C/A (rs1800630), −857 C/T (rs1799724), −308 G/A (rs1800629), and −238 G/A (rs361525), and one SNP upstream from the transcription start site (+489) rs1800610 of TNF-α were analyzed using induced heteroduplex generation. A functional NF-κB1 indel (−94) was also investigated. Haplotypes were inferred by PHASE and associations with rejection were determined by chi-square analysis. ResultsThe TNF-α haplotype TCTGGA was significantly associated with reduced risk of corneal graft rejection (Pc < .005) and TCTAGA was associated with increased risk of rejection (Pc < .005) in high-risk corneal transplants. There was no association with the NF-κB1 indel (Pc > .05). ConclusionAccording to haplotype frequencies, our results suggest that the TCTGGA haplotype may confer additional protection against risk of immunological rejection whereas TCTAGA may increase risk of corneal allograft rejection in the high-risk setting. However, both haplotypes were relatively rare and thus would not warrant genotyping for individual patient selection for anti-TNF therapy.

Influence of different surfactants on the technological properties and in vivo ocular tolerability of lipid nanoparticles.

Addition of one or more surfactant agents is often necessary for the production of nanostructured lipid and polymeric systems. The removal of residual surfactants is a required step for technological and toxicological reasons, especially for peculiar applications, such as the ophthalmic field. This study was planned to assess the technological properties of some surfactants, commonly used for the production of lipid nanoparticles, as well as their ocular safety profile. Stable and small-size solid lipid nanoparticles were obtained using Dynasan(®) 114 as the lipid matrix and all the tested surfactants. However, from a toxicological point of view, the nanocarriers produced using Kolliphor(®) P188 were the most valuable, showing no irritant effect on the ocular surface up to the highest tested surfactant concentration (0.4%, w/v). The SLN produced using Cremophor(®) A25 and Lipoid(®) S100 were tolerated up to a surfactant concentration of 0.2% by weight, while for Tween(®) 80 and Kolliphor(®) HS 15 a maximum concentration of 0.05% can be considered totally not-irritant.

Aqueous carboxymethyl gum kondagogu as vehicle for ocular delivery

Aqueous solutions of carboxymethyl gum kondagogu (CMGK), an anionic bioadhesive polymer were evaluated as vehicles for ophthalmic delivery using tropicamide as a model drug. Aqueous ophthalmic solution of tropicamide (1 %, w/v) in CMGK (5 %, w/v) dispersions were formulated. The aqueous CMGK vehicle, formulated tropicamide eye drops and commercial tropicamide formulations were assessed comparatively for ex vivo ocular tolerance using hen’s egg chorioallantoic membrane assay. The results indicated ocular tolerability of aqueous CMGK vehicle. The results of comparative ex vivo corneal permeation study of tropicamide from the aqueous CMGK vehicle (5 %, w/v) conducted across isolated goat cornea revealed a no significant difference in the corneal permeation of tropicamide from the CMGK vehicle based formulation as compared to the commercial formulation. Further, the results of in vivo mydriatic response study conducted in rabbits revealed a non significant difference in the mydriatic response of tropicamide from the aqueous CMGK vehicle and commercial formulations. In conclusion, CMGK can be used as an ocularly tolerable polymer for formulating ophthalmic dosage forms.

Chitosan nanoparticles amplify the ocular hypotensive effect of cateolol in rabbits

PurposeTo assess the potential of chitosan (CS) nanoparticles for ocular drug delivery by investigating their intraocular retention by γ-scintigraphy and intraocular pressure reduction. MethodsCarteolol (CRT) loaded CS-NPs were prepared by ionotropic gelation method. A four-factor three-level Box–Behnken design was employed to investigate the influence of independent variables on particle size, loading capacity and entrapment efficiency. Characterization was done for particle size, encapsulation efficiency, loading capacity and in vitro drug release and transcorneal permeation, histopathology and confocal microscopy, in vitro ocular tolerance. Intraocular retention was assessed by γ-scintigraphy, and intraocular pressure was measured by tonometer betamethasone induced glaucoma rabbits. Results and discussionThe optimized nanoparticles showed a particle size of 243nm (PDI – 0.304±0.04) and drug loading 49.21±2.73% with entrapment efficiency of 69.57±3.54%. In vitro release studies showed a sustained release for 24h as compared to drug solution. Ex vivo studies showed good permeation with non-significant changes in cornea anatomy indicating its safe nature. γ-Scintigraphy study showed good spread and retention (<0.05) in precorneal area as compared to the aqueous CRT solution and prolonged reduction in intraocular pressure (P<0.001). ConclusionThese results indicate that CS nanoparticles are promising vehicles of CRT for ocular drug delivery.

Preparation, characterization and evaluation of novel elastic nano-sized niosomes (ethoniosomes) for ocular delivery of prednisolone

Niosomes embodying ethanol and minimum amount of cholesterol (ethoniosomes) could be promising ocular delivery systems for water soluble and insoluble drugs. This manuscript reports on novel nano-sized elastic niosomes (ethoniosomes) composed of Span 60: cholesterol (7:3 mol/mol) and ethanol, for ocular delivery of prednisolone acetate (Pred A) and prednisolone sodium phosphate (Pred P). These ethoniosomes were prepared with the thin film hydration (TFH) and ethanol injection (EI) methods, characterized for percentage entrapment efficiency (% EE), size, zeta potential, morphology, elasticity, in vitro release and physical stability. Ocular irritation, bioavailability and anti-inflammatory effects were evaluated and compared with the conventional suspension and solution eye drops. The prepared ethoniosomal vesicles (EV) had a Z-average diameter of 267 nm, zeta potential of approximately −40 mV and % change in size after extrusion of 4%. They were physically stable for at least 2 months at 4 °C. The prepared EV showed good ocular tolerability using the modified Draize’s test and the estimated relative ocular bioavailability for Pred A EV and Pred P EV was 1.54 and 1.75 times greater than that for the suspension and solution eye drops, respectively. The time required for complete healing from the clove oil-induced severe ocular inflammation was reduced to half with Pred A and Pred P EV. More interestingly, the intraocular pressure (IOP) elevation side effect recorded for Pred A and Pred P EV was significantly less than that for the conventional suspension and solution eye drops.

Investigation of moxifloxacin loaded chitosan-dextran nanoparticles for topical instillation into eye: In-vitro and ex-vivo evaluation.

Introduction:Management of ocular surface disease by conventional formulation is limited by poor residence of drug at cul-de-sac of eye. To overcome this limitation, prolonged released mucoadhesive chitosan (CS)–dextran sulfate (DS) nanoparticles (NPs) were investigated for the prolonged topical ophthalmic delivery of moxifloxacin (Mox).Methods:Formulation was optimized by 3-factors (CS, DS, and Mox concentration), 3-levels (−1, 0, +1) Box-Behnken design. Optimized formulation was characterized for various in-vitro attributes, including particles size, zeta potential, shape and morphology, in-vitro release profile, corneal permeation, corneal retention, ocular tolerance test as well as antimicrobial activity.Results:Average hydrodynamic particle size of statistically optimized formulation was found to be 279.18 ± 15.63 nm with good polydispersity index, 0.367 ± 0.016 and positive zeta potential, +31.23 ± 1.32. NPs showed entrapment efficiency, 72.82 ± 3.6% and transmission electron microscopic analysis revealed a spherical shape of particles. Formulation exhibited biphasic release profile with an initial fast release (≈25% in 1st h) followed by sustained release (≈95% in next 24 h) following Korsmeyer–Peppas model with a nonFickian diffusion process. Mox loaded CS-DS NPs exhibited a significantly higher (P < 0.01), approximately 1.8-fold transcorneal permeation as well as significantly higher corneal retention (P < 0.01), around 4-5-fold when compared to free solution. Developed formulation exhibited safety profile comparable to normal saline, which was revealed by ocular tolerance test (Hen's egg test-chorioallantoic membrane). Mox-CS-DS NPs exhibited significantly high (P < 0.01) antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa.Conclusion:In-vitro and ex-vivo studies revealed that developed formulation could be a potential substitute for prolonged topical ocular delivery.

Phase I Clinical Trial of SYL040012, a Small Interfering RNA Targeting β-Adrenergic Receptor 2, for Lowering Intraocular Pressure

The objective of this study was to evaluate ocular tolerance, safety, and effect on intraocular pressure (IOP) of a topically administered small interfering RNA; SYL040012, on healthy volunteers. The study was an open-label, controlled, single-center study comprised of two intervals that enrolled 30 healthy subjects having IOP below 21 mmHg. SYL040012 was administered to one eye as a single dose to six subjects during interval 1. During interval 2 two different doses of SYL040012 were administered to one eye on a daily basis to two separate groups of 12 subjects each, over a period of 7 days. The contralateral eye was evaluated but not administered and served as control for the tolerance study. SYL040012 was well tolerated locally. No local or systemic adverse events related to the product developed in response to any of the doses studied. SYL040012 was not detected in plasma at any time point. Administration of SYL040012 over a period of 7 days reduced IOP values in 15 out of 24 healthy subjects regardless of the dose used. IOP decrease was statistically significant in response to one of the doses tested and responsiveness to SYL040012 seemed to be greater in individuals with higher baseline IOP.

Comparison of preservative-free ketotifen fumarate and preserved olopatadine hydrochloride eye drops in the treatment of moderate to severe seasonal allergic conjunctivitis

To compare preservative-free ketotifen 0.025% ophthalmic solution to olopatadine 0.1% ophthalmic solution in with the treatment of seasonal allergic conjunctivitis (SAC) in clinical practice. This was a comparative, randomised, investigator-masked, pilot clinical study in adult patients with documented history of SAC and presenting with moderate to severe itching and conjunctival hyperemia. Eligible patients initiated either ketotifen or olopatadine treatment at a dose of one drop twice daily for 28days. The resolution of ocular signs and symptoms was assessed on day 7 and day 28. Itching was also assessed within 15minutes following the first instillation (day 0). Conjunctival impression cytology was performed at each visit to assess the evolution of ICAM-1 expression (day 0, 7 and 28). Seventy-five patients were randomised (ketotifen: 38 patients; olopatadine: 37 patients). At day 28, the composite score for primary criteria (itching, tearing, and conjunctival hyperemia) improved from 6.8±1.2 to 0.9±1.0 in the Ketotifen group, without statistically significant difference between treatment groups (P=0.67). There was no relevant difference between treatment groups in other efficacy parameters, except a trend for a more rapid resolution of conjunctival hyperemia in the Ketotifen group. Both drugs were well tolerated, with a trend for a better tolerability reported by patients on ketotifen compared to those on olopatadine at day 7 (P=0.054). A rapid and comparable improvement in SAC was achieved after 28days of treatment with both preservative-free ketotifen and preserved olopatadine ophthalmic solutions, with a slightly better ocular tolerance with unpreserved ketotifen 0.025% eye drops.

Evaluation of the Pharmacokinetics and Ocular Tolerance of a Microemulsion Containing Tacrolimus

Tacrolimus is a potent immunosuppressive agent with limited corneal penetration. Microemulsions can increase the drug solubility and enhance drug absorption in the eye. This work aimed to develop a tacrolimus microemulsion as well as to characterize and to evaluate its ocular tolerance and pharmacokinetics after topical application in rabbits. The microemulsion was prepared by the titration with the cosurfactant technique and its physical-chemical parameters and stability were determined. The cytotoxicity was evaluated using the corneal epithelium and conjunctiva cell lines. The ocular pharmacokinetic parameters in rabbits were determined and compared with that obtained after instillation of tacrolimus suspension. The microemulsion containing tacrolimus was successfully developed. It was nonirritating to rabbits' eyes and it was also not toxic to the corneal and conjunctival cells. When compared to the suspension, the microemulsion containing tacrolimus presented higher values of AUC (2,912.5±245.4 min.ng/mL vs. 1,669.8±93 min.ng/mL) and Cmax (26.8±2.3 ng/mL vs. 20.7±2.8 ng/mL). On the other hand, the Cl/F value was smaller when compared to the suspension that may decrease the number of applications of eye drops. The developed microemulsion could be an alternative to reduce the systemic adverse effects of tacrolimus and, consequently, increase the patient compliance to the treatment.

English

This study deals with ophthalmic gel of aceclofenac which is potent non-steroidal antiinflammatory drugs (NSAIDs) and was formulated using polymers hydroxy propyl methyl cellulose (HPMC) (15) cps with methyl cellulose (40) cps and HPMC (15) cps with Carbopol (940). The gels (HP with MC) and (HP with CB), were sterilized and assessed for various parameters like clarity, pH, physical appearance, physical stability, viscosity and uniformity of drug content. The release rate from the aforementioned formulation within a period of 9 h were almost HP with MC batch H4 (84.66%) and for HP with CB batch C1 (80.46%); both ophthalmic gels obeyed zero order kinetics for drug release. The ocular irritation was carried out on male albino rabbits and found no redness, no inflammation and no increases tear. Both formulations in gel were found to be more stable at ambient, refrigerator and incubated temperature. The stability of the gels was evidenced by the degradation rate constant. Ophthalmic gel formulated by HP with MC and HP with CB gels proves to be viable alternative to conventional eye drops as it offers longer precorneal residence time and excellent ocular tolerance. Key words:&nbsp;Carbopol 940 (CB), ophthalmic, gel, hydroxy propyl (HP), methyl cellulose (MC).

Gellan–thioglycolic acid conjugate: Synthesis, characterization and evaluation as mucoadhesive polymer

Gellan–thioglycollic acid conjugate was synthesized with the objective to improve its mucoadhesive properties. Synthesis of conjugate was confirmed by –SH stretch in the Fourier-transform infrared spectra at 2571cm−1. It was found to contain 13.92mM of thiol groups/g of the conjugate. Thiolation of gellan gum was found to slightly increase its degree of crystallinity and decrease its sensitivity to Ca2+-induced gelation. On screening of gellan–thioglycollic acid conjugate for ex-vivo ocular tolerance using hen's egg chorio-allantoic membrane test and for biocompatibility by resazurin assay on Vero-cells, it was found to be non-irritant and biocompatible. Metronidazole gels formulated using gellan thioglycollic acid conjugate as bioadhesive agent showed 1.82-fold higher mucoadhesive strength than the gels formulated using gellan gum. Further, the metronidazole gels containing gellan and gellan–thioglycollic conjugate released the drug following first-order and Higuchi's square-root release kinetics. In conclusion, gellan–thioglycollic acid conjugate is a promising bioadhesive excipient.

Betaxolol Hydrochloride Loaded Chitosan Nanoparticles for Ocular Delivery and their Anti-glaucoma Efficacy

Many effective anti-glaucoma drugs available for the treatment of ocular hypertension and open angle glaucoma are associated with rapid and extensive precorneal loss caused by the drainage and high tear fluid turnover. The present study involved design of mucoadhesive nanoparticulate carrier system containing betaxolol hydrochloride for ocular delivery to improve its corneal permeability and precorneal residence time. Nanoparticles were prepared by spontaneous emulsification method and had a particle size of 168-260 nm with zeta potential of 25.2-26.4 mV. The in vitro release studies in simulated tear fluid exhibited biphasic release pattern with an initial burst followed by sustained release upto 12 h. The sterility tests confirmed that formulation was free from viable microorganisms and suitable for ocular delivery. The ocular tolerance of nanoparticles was evaluated using Hen Egg-Chorion Allantoic Membrane (HE-CAM) method and was found to be non-irritant. Stability studies of nanoparticles revealed that there was no significant change in particle size and drug content after storage at 25 ± 2°C/60 ± 5% RH over a period of 3 months. In vivo pharmacodynamic studies were carried out in dexamethasone induced glaucoma model in rabbits. The developed nanoparticles showed significant decrease in intraocular pressure (IOP) compared to marketed formulation. Optimized formulation of BN3 showed gradual reduction of IOP reaching peak value of 9.9 ± 0.5mm Hg, equivalent to 36.39 ± 1.84% reduction in IOP compared to control at the end of 5 h which was significant (p < 0.05) compared to marketed formulation. Thus, our studies demonstrate that developed nanoparticles offer a promising delivery system for the management of glaucoma.

Ocular tolerability of preservative‐free prostaglandin eye drops

AbstractPurpose Taflotan® (tafluprost) and Monoprost® (latanoprost) are preservative‐free anti‐glaucoma eye drops. In order to compare the ocular irritation potential these preservative‐free prostaglandin products were instilled repeatedly on rabbit eyes. Cell viability in vitro was studied using immortalized human corneal epithelial (HCE) cells.Methods To study the in vitro cytotoxicity of Taflotan and Monoprost, HCE cells were exposed to the test solutions for 5 to 30 minutes, after which the cytotoxicity was evaluated by MTS assay. Secondly, to compare their in vivo ocular tolerance, Taflotan or Monoprost solution was instilled 10 times at 30‐minute intervals onto eyes of male albino rabbits. Left eyes were treated while right eyes remained as untreated controls. Besides scoring macroscopic findings using MacDonald‐Shadduck system, slit lamp examination and corneal fluorescein staining were performed after the last instillations.Results In MTS test, the 30 minutes treatment with Taflotan had no effect on the cell viability, whereas the cell viability was decreased by Monoprost treatment. After repeated instillations on rabbit eyes conjunctival redness and swelling were observed in both groups. Their irritation scores and occurring frequency were lower in Taflotan treated eyes than in those treated with Monoprost. In addition, discharge was observed only in Monoprost treated eyes from 30 minutes until 3 hours after the last instillation.Conclusion Under the conditions of this study, the ocular irritation potential of Taflotan was weaker than that of Monoprost. The results indicate that Taflotan eye drops may have a better ocular tolerability profile than Monoprost. Commercial interest

Ocular biocompatibility and tolerance study of biodegradable polymeric micelles in the rabbit eye

Polymeric nanoparticles have been developed to improve the bioavailability of drugs applied in ocular drug delivery. However, there are few information on ocular biocompatibility of polymeric nanoparticles applied topically onto the eye. In this paper, the ocular biocompatibility and tolerance of methoxy poly(ethylene glycol)–poly(ɛ-caprolactone) (MPEG–PCL) micelles (∼50nm) were investigated in rabbit eyes after a single intracameral and intravitreal injections. In vitro cytotoxicity assays showed that MPEG–PCL micelles had no apparent cytotoxicity against human corneal epithelial cells (HCEC), human lens epithelial cells (HLEC), and retinal pigment epithelial cells (RPE cells) at micelle concentrations of 0–2mg/mL. After a single intracameral injection of 0.2mL MPEG–PCL micelles (200mg/mL) into rabbit eyes, MPEG–PCL micelles were slowly removed from aqueous humor in a period of 14 days, while the intraocular pressure (IOP) was maintained at nearly the same level for 15 days. Three days after intracameral injection, dual staining of corneal endothelium showed that the endothelial cells were nearly regular hexagon-shape with well-defined organization, similar to normal endothelial cells. Hematoxylin and eosin staining indicated that there was absence of any obvious changes in microstructure of the corneal tissue and retina after a single intracameral and intravitreal injection of 0.2mL MPEG–PCL micelles (100mg/mL, 150mg/mL, and 200mg/mL). This study provides valuable information (safety and biocompatibility) for biomedical researchers to develop MPEG–PCL micelles as candidates for ocular drug delivery.