Safety comparison of additives in antiglaucoma prostaglandin (PG) analog ophthalmic formulations

Preventative Effect of Topical Rebamipide Against Corneal Epithelium Disorders Caused by Diclofenac Sodium

Purpose: This study aimed to investigate the relationship between diclofenac sodium ophthalmic solution (DFNa) and corneal epithelial cell damage and to evaluate the preventive effect of rebamipide (RBM) on it. Methods: DFNa, DFNa/preservative-free (PF), or 0.5% chlorobutanol (CB) solution was instilled into the conjunctival sac of a normal rabbit eye, and corneal resistance measurement (using a corneal resistance device [CRD]) was performed 120 min after the end of instillation. Then, fluorescent staining (FL), corneal tissue staining (hematoxylin and eosin [H&E]), and immunostaining (zona occlusion-1) were performed (RBM-untreated group). However, RBM was instilled into the eyes of another group of normal rabbits, followed by each of the solutions; 120 min after the end of instillation, all evaluations were performed for this group (RBM treatment group). Results: Using the CRD method, in the RBM-untreated group, corneal resistance (CR; %) was found to be significantly reduced in DFNa (79.9 ± 19.4%), DFNa/PF (89.1 ± 17.3%), and 0.5% CB (83.8 ± 10.6%). In addition, DFNa and 0.5% CB solutions showed positive staining in the FL staining method. In the H&E staining method, some clear voids were observed in the outermost layer of the cornea using DFNa and 0.5% CB solutions. However, corneal epithelial damage was suppressed in the RBM treatment group. ZO-1 immunostaining in DFNa and 0.5% CB solutions revealed discontinuous localization of ZO-1 at the cell periphery. Conclusions: RBM eye drops were effective in preventing corneal epithelial damage caused by DFNa eye drops, and CB was considered to be the main causative agent of this damage.

From Eye Care to Hair Growth: Bimatoprost

BACKGROUND

Bimatoprost has emerged as a significant medication in the field of medicine over the past several decades, with diverse applications in ophthalmology, dermatology, and beyond. Originally developed as an ocular hypotensive agent, it has proven highly effective in treating glaucoma and ocular hypertension. Its ability to reduce intraocular pressure has established it as a first-line treatment option, improving management and preventing vision loss. In dermatology, bimatoprost has shown promising results in the promotion of hair growth, particularly in the treatment of alopecia and hypotrichosis. Its mechanism of action, stimulating the hair cycle and prolonging the growth phase, has led to the development of bimatoprost-containing solutions for enhancing eyelash growth.

AIM

The aim of our review is to provide a brief description, overview, and studies in the current literature regarding the versatile clinical use of bimatoprost in recent years. This can help clinicians determine the most suitable individualized therapy to meet the needs of each patient.

METHODS

Our methods involve a comprehensive review of the latest advancements reported in the literature in bimatoprost formulations, which range from traditional eye drops to sustained-release implants. These innovations offer extended drug delivery, enhance patient compliance, and minimize side effects.

RESULTS

The vast literature published on PubMed has confirmed the clinical usefulness of bimatoprost in lowering intraocular pressure and in managing patients with glaucoma. Numerous studies have shown promising results in dermatology and esthetics in promoting hair growth, particularly in treating alopecia and hypotrichosis. Its mechanism of action involves stimulating the hair cycle and prolonging the growth phase, leading to the development of solutions that enhance eyelash growth. The global use of bimatoprost has expanded significantly, with applications growing beyond its initial indications. Ongoing research is exploring its potential in glaucoma surgery, neuroprotection, and cosmetic procedures.

CONCLUSIONS

Bimatoprost has shown immense potential for addressing a wide range of therapeutic needs through various formulations and advancements. Promising future perspectives include the exploration of novel delivery systems such as contact lenses and microneedles to further enhance drug efficacy and patient comfort. Ongoing research and future perspectives continue to shape its role in medicine, promising further advancements and improved patient outcomes.

New Preservative-Free Formulation for the Enhanced Ocular Bioavailability of Prostaglandin Analogues in Glaucoma

Glaucoma is a wide-spread eye disease caused by elevated intraocular pressure. Uncontrolled, this pressure may lead to damages to the optic nerve. Prostaglandin analogues, such as latanoprost and travoprost (which are water-insoluble active substances), are the most used class of active pharmaceutical ingredient. To administer them as eye drops, preservatives, such as benzalkonium chloride, are used as solubilizers. The latter is known to cause a local inflammation when used chronically and is not recommended for patients with ocular surface disorders. In this work, we sought to use polysorbate 80 (PS80) as a solubilizing agent simultaneously with sodium hyaluronate (NaHA) as a thickener and cytoprotective agent for the corneal surface. The first part of this study assessed the compatibility of the excipients with the active substance, using physicochemical methods such as spectra fluorescence and differential scanning calorimetry (DSC), as well as the solubilization mechanism of PS80 regarding prostaglandin analogues using nuclear magnetic resonance (NMR). The second part evaluated the stability of a formula candidate, its viscosity upon instillation, and its pharmacokinetic profile in rabbits as compared to the commercially approved medicine Travatan®. The results show that sodium hyaluronate is inert with respect to travoprost, while PS80 successfully solubilizes it, meaning that benzalkonium chloride is no longer required. Moreover, the pharmacokinetic profiles of the rabbits showed that the original formula described in the present study enhanced the ocular bioavailability of the drug, making it a promising product to control intraocular pressure with a potential reduced dosage of travoprost, therefore minimizing its related side effects.

Polyvinyl alcohol-iodine induced corneal epithelial injury in vivo and its protection by topical rebamipide treatment

Periocular povidone-iodine (PI) and polyvinyl alcohol-iodine (PAI) have had a major role in the prevention of endophthalmitis. The purpose of this study was to investigate the corneal epithelial toxicity of PAI in a rabbit eye model using corneal resistance (CR) measurement, which is a good indicator of cell barrier function. Rabbit eyes were administered PAI solution at 4-, 6-, 8-, or 16-fold dilution with physiological saline solution (saline) or saline alone (control), to the conjunctival sac with/without wash-out with saline. Corneal epithelial injury assessed by fluorescein staining and the CR ratio was measured at 10 minutes (min) to 96 hours (h) after the initial administration. Histological observation was performed in the eyes following the PAI or control administrations. At 120 min after administration of PAI solution, the CR ratio was decreased and superficial punctate keratopathy (SPK) was significantly increased in each of the PAI-administered groups compared to the control. Recovery of CR and SPK after administration of 6- or 8-fold dilution of PAI was significantly delayed in eyes that were not subsequently washed with saline compared with eyes that were. Pre- or post-instillation of 2% rebamipide ophthalmic suspension significantly reduced PAI induced-SPK and -decrease of CR ratio. The CR method was able to accurately and quantitatively evaluate fine corneal epithelial injury. It is suggested that eyes should be washed with saline solution after administration of PAI solution or the instillation of rebamipide to prevent or reduce corneal epithelial injury.

A Novel Method to Eliminate Preservatives in Eye Drops

PURPOSE

Multiuse eye drops must maintain sterility and typically accomplish this by added preservatives. However, preservatives often cause harmful side effects. A gauze barrier dressing ("BIOGUARD^®") recently cleared by the FDA has an immobilized poly diallyldimethylammonium chloride (p-DADMAC) coating and is an effective antimicrobial with minimal compound release into solution. To implement use of this dressing as a replacement for preservatives in multidose eye drop bottles, its ability to maintain sterility without interacting with the active ingredient (AI) of the ophthalmic medication was tested.

METHODS

To determine immobilized p-DADMAC's microbicidal efficacy, it was added to eye drop bottles, then contaminated with Staphylococcus aureus (SA113) bacteria. To assess interference with AI in eye drops, high performance liquid chromatography was used to determine whether the AIs timolol and dorzolamide were affected after exposure to p-DADMAC. To further investigate effects on AI, the microbicidal activity of Vigamox^® (moxifoxacin) was assessed after p-DADMAC gauze exposure.

RESULTS

S. aureus bacteria were eliminated by p-DADMAC-treated gauze for all samples. The concentrations of both timolol and dorzolamide increased after exposure to p-DADMAC-treated gauze, but spectrometric analysis showed that this did not occur when the p-DADMAC-coated material was presoaked in deionized water. The microbicidial activity of moxifloxacin was unaffected by exposure to p-DADMAC-treated gauze.

CONCLUSIONS

Due to its lack of effect on eye drop AI and its microbicidal efficacy, p-DADMAC treatment would make an excellent candidate for replacing preservatives in eye drops.

In Vivo Measurement of Human Corneal Impedance Value

PURPOSE

To examine the validity of in vivo electrical corneal resistance (CR) measurements taken by a corneal resistance device (CRD).

METHODS

Eighty-two eyes (mean age ± SD, 50.1 ± 23.3; range, 22-87 years: 50 eyes of 33 males and 32 eyes of 17 females) of patients who had undergone cataract surgery and volunteers at the Kanazawa Medical University Hospital were enrolled. The CR was compared among gender; age; side, that is, left versus right eye; healthy (fluorescein-negative) versus epithelium-injured eyes (fluorescein-positive), corneal radius of curvature; corneal endothelial cell count; and corneal thickness.

RESULTS

The mean ± SD of the CR in the 82 eyes was 273.2 ± 78.2 Ω. By age group, the mean ± SD CR was 283.3 ± 87.4 Ω (30 eyes) in the 20s, 275.0 ± 50.0 Ω (4 eyes) in the 30s, 266.7 ± 70.7 Ω (9 eyes) in the 40s, 257.1 ± 53.5 Ω (7 eyes) in the 50s, 242.9 ± 78.7 Ω (7 eyes) in the 60s, 266.7 ± 84.0 Ω (18 eyes) in the 70s, and 300.0 ± 81.6 Ω (7 eyes) in the 80s, with no significant difference among the groups. By gender, the mean ± SD CR was 270.0 ± 83.0 Ω (50 eyes) in males and 278.0 ± 71.0 Ω (32 eyes) in females. By side, the CR values were 282.9 ± 83.4 Ω (44 eyes) in the right eye, 265.9 ± 71.3 Ω (41 eyes) in the left eye, with no significant difference among the groups. By status, the values were 280.0 ± 70.0 Ω (44 eyes) in healthy eyes and 200.0 ± 144.2 Ω (13 eyes) in injured eyes, with a significant between-group difference (P = 0.009). The mean ± SD corneal thickness (0.56 ± 0.03 mm) in 46 healthy eyes was slightly correlated with the CR.

CONCLUSIONS

The CRD quantitatively measured the CR in healthy eyes. The CR did not differ significantly by age, gender, or left versus right eye. The significant difference in CR between the healthy and injured eyes showed that the measurements have validity.

[Original preparations versus generics--latanoprost: how similar is different?]

BACKGROUND

To test the interchangeability of the commercially available (in Germany) latanoprost drugs and their generics respectively, the concentration of the active substance was tested. Guidelines of the European Medicines Agency postulate a sufficient bioequivalence, if the range of the agent is within 80-125% of the original drug.

METHODS

All compounds of latanoprost were procured registered. The concentration of latanoprost and benzalkoniumchloride was measured by high-performance liquid chromatography (HPLC) in a validated reference labroratory for 23 generics. In addition, the mean volume of drops and the pH of the formulation were measured. The packaging label and the readability of the enclosed information leaflet were checked.

RESULTS

All products contained less than 50 μg/ml latanoprost. The deviating reduction of the active substance (mean: - 7.39%, ± 2.8%) was accompanied by fluctions of the eyedrops' mass (mean: 0.03 g, ± 0.002 g). The concentration of benzalkonium chloride was mostly increased (median: 5.45%, min: - 2.5%, max: 11.5%). The pH of the original drug and the generics (median 6.78, min: 6.62, max: 6.81) was similar to the original drug, but was significantly different from an unpreserved formulation (pH 7.18). Due to type size, the packaging leaflet was illegible for humans with impaired vision.

CONCLUSIONS

Before prescribing generics in ophthalmology, different factors have to be considered, which might influence the amount of IOP lowering in effect. In the absence of healthcare research it is still unclear, how different bottle forms of eyedrops--such as appearance (e.g. Cyrillic characters) or pressure point (administration)--reduce the adherence of glaucoma patients.