Stability of an ophthalmic micellar formulation of cyclosporine A in unopened multidose eyedroppers and in simulated use conditions

Imatinib@glycymicelles entrapped in hydrogel: preparation, characterization, and therapeutic effect on corneal alkali burn in mice

Imatinib (IMB) is a type of tyrosine kinase inhibitor with great application potential for inhibiting corneal neovascularization (CNV), but its poor water solubility limits its application in eye disease treatment. In this study, novel IMB@glycymicelles entrapped in hydrogel (called IMB@glycymicelle-hydrogel) were prepared, characterized, and evaluated for their therapeutic effects on corneal alkali burn in mice. Imatinib could be successfully loaded in glycymicelles using glycyrrhizin as a nanocarrier with an optimized weight ratio of IMB:nanocarrier. The apparent solubility of IMB was significantly improved from 61.69 ± 5.55 μg/mL to bare IMB to 359,967.62 ± 20,059.42 μg/mL to IMB@glycymicelles. Then, the IMB@glycymicelles were entrapped in hydrogel fabricated with hydroxypropyl methylcellulose and sodium hyaluronate (HA) to prolong retention time on the ocular surface. Rabbit eye tolerance tests showed that IMB@glycymicelle-hydrogel possessed good ocular safety profiles. In a mouse model of corneal alkali burns, the topical administration of IMB@glycymicelle-hydrogel showed strong efficacy by prompting corneal wound healing, recovering corneal sensitivity, relieving corneal opacities, and inhibiting CNV, and these efficacy evaluation parameters were better than those of the positive drug HA. Overall, these results demonstrated that IMB@glycymicelle-hydrogel may be a promising candidate for the effective treatment of alkali ocular damage.

Influence of filtering on the effective concentration and sterility of a 2% cyclosporine ophthalmic solution: a quality improvement perspective

BACKGROUND

Pharmaceutical companies do not sell formulations for all diseases; thus, healthcare workers have to treat some diseases by concocting in-hospital preparations. An example is the high-concentration 2% cyclosporine A (CyA) ophthalmic solution. Utilizing a filter in sterility operations is a general practice for concocting in-hospital preparations, as is the case for preparing a 2% CyA ophthalmic solution. However, whether filtering is appropriate concerning the active ingredient content and bacterial contamination according to the post-preparing quality control of a 2% CyA ophthalmic solution is yet to be verified.

METHODS

We conducted particle size, preparation concentration, and bacterial contamination studies to clarify aforementioned questions. First, we measured the particle size of CyA through a laser diffraction particle size distribution. Next, we measured the concentration after preparation with or without a 0.45-µm filter operation using an electrochemiluminescence immunoassay. Finally, bacterial contamination tests were conducted using an automated blood culture system to prepare a 2% CyA ophthalmic solution without a 0.45 μm filtering. Regarding the pore size of the filter in this study, it was set to 0.45 μm with reference to the book (the 6th edition) with recipes for the preparation of in-hospital preparations edited by the Japanese Society of Hospital Pharmacists.

RESULTS

CyA had various particle sizes; approximately 30% of the total particles exceeded 0.45 μm. The mean ± standard deviation of filtered and non-filtered CyA concentrations in ophthalmic solutions were 346.51 ± 170.76 and 499.74 ± 76.95ng/mL, respectively (p = 0.011). Regarding bacterial contamination tests, aerobes and anaerobes microorganisms were not detected in 14 days of culture.

CONCLUSIONS

Due to the results of this study, the concentration of CyA may be reduced by using a 0.45-µm filter during the preparation of CyA ophthalmic solutions, and furthermore that the use of a 0.45-µm filter may not contribute to sterility when preparing CyA ophthalmic solutions.

Stability of voriconazole 10 mg/mL ophthalmic solution during 90 days

Objectives

Fungal keratitis is a rare but severe cause of infectious keratitis and can lead to blindness. To cure fungal keratitis, antifungal like voriconazole eye drops must be immediately administered. As no brand is available on the market, voriconazole ophthalmic solution is compounded in hospital pharmacies using voriconazole powder for intravenous infusion. The aims of our study were to both assess the physico-chemical and microbiological stability of eye drop solutions stored at +2 to 8 °C. Two different High-Density-Polyethylene (HDPE) eye drop dispensing containers were assessed, one with a sterility preserving cap Novelia®(Nemera) and the other without sterility preserving cap both provided by CAT laboratory. In addition microbiological quality was assessed during 15 days simulated patient use.

Methods

Multiple batches of voriconazole 10 mg/mL eye drops were prepared and stored at +2 to 8 °C to study their stability over 90 days. All analyses were performed in triplicate. Physical stability was determined, pH determination, osmolarity measurement, and a particle count test was also performed. A high performance liquid chromatography (HPLC-UV) stability indicating method was used to determine chemical stability of the ophthalmic solution over 90 days of storage. For microbiological stability, a sterility test was performed using closed membrane filtration method (Steritest®, Merck Millipore) at D0, D90 and D90+15 days after simulated administration of eye drops (D90+15).

Results

For both containers, no variation of visual aspect, pH, osmolality, particle count and final concentration were observed. No microbiological growth was observed after 90 days of storage. At the end of the simulated administration period (D+15), unconstant microbiological growth was only observed in HDPE vials without sterility preserving cap, whereas HDPE vials with a sterility preserving cap Novelia®(Nemera) remained sterile.

Conclusions

Voriconazole 10 mg/mL ophtalmic solution was stable during 90 days at +2 to 8 °C in lightproof HDPE vials without sterility preserving cap and HDPE vials with a sterility preserving cap Novelia®(Nemera). However, vials with classical cap which are not airtight systems, may microbiologically contaminated during patient’s use than vials with Novelia® cap thanks to their innovative valve system.

Physicochemical Stability of a Novel Tacrolimus Ophthalmic Formulation for the Treatment of Ophthalmic Inflammatory Diseases

Tacrolimus is an immunosuppressant used to treat a large variety of inflammatory or immunity-mediated ophthalmic diseases. However, there are currently no commercial industrial forms available that can provide relief to patients. Various ophthalmic formulations have been reported in the literature, but their stability has only been tested over short periods. The objective of this study was to evaluate the physicochemical stability of a preservative-free tacrolimus formulation (0.2 and 1 mg/mL) at three storage temperatures (5 °C, 25 °C and 35 °C) for up to nine months in a multidose eyedropper. Analyses performed were the following: visual inspection and chromaticity, turbidity, viscosity, size of micelles, osmolality and pH measurements, tacrolimus quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. In an in-use study, tacrolimus quantification was also performed on the drops emitted from the eyedroppers. All tested parameters remained stable during the nine month period when the eyedrops were stored at 5 °C. However, during storage at 25 °C and 35 °C, several signs of chemical instability were detected. Furthermore, a leachable compound originating from a silicone part of the eyedropper was detected during the in-use assay. Overall, the 0.2 mg/mL and 1 mg/mL tacrolimus ophthalmic solutions were physicochemically stable for up to nine months when stored at 5 °C.

Topical preservative-free ophthalmic treatments: an unmet clinical need

Introduction: The main role of preservatives in eyedrops is to ensure sterility and microbiological integrity of the drug, and to facilitate the penetration of active compounds into the eye. However, several studies documented significant toxic effects induced by preservatives, especially on the ocular surface. Consequently, most of the ophthalmic medications became progressively available in preservative-free (PF) formulations.Areas covered: We analyzed pre-clinical and clinical studies on PF eyedrops with particular attention to common chronic diseases such as dry eye and glaucoma. We discussed about the pros and cons of using PF eyedrops, in terms of efficacy, safety, and social-economic aspects.Expert opinion: There are still unresolved issues that make hard for PF medications to definitively conquer the drug market. Despite robust pre-clinical evidences of less toxicity, the low number of randomized clinical trials does not permit to state that PF eyedrops have, in clinical practice, a similar efficacy or a higher safety compared to preserved forms. These aspects limit their use to chronic diseases requiring long-term therapies with multiple daily instillations, especially in the presence of concomitant ophthalmic diseases that expose to a risk of ocular surface worsening.

Neuroprotective effect of melatonin loaded in ethylcellulose nanoparticles applied topically in a retinal degeneration model in rabbits

We are reporting for the first time the synthesis and application of an innovative nanometric system for the controlled topic release of melatonin in the retina. The ethylcellulose nanocapsules were characterized by diverse physicochemical techniques (scanning electron microscopy, zeta potential, hydrodynamic diameters) and an in vitro release study was done. A complete ex vivo and in vivo trans-corneal permeation and an irritation study were carried out with the new formulations in albino rabbits, to which a retinal degenerative model was induced. The results obtained demonstrate that the in vitro release of melatonin (1 mg/mL and 2 mg/mL) transported by nanocapsules is slower when compared to a solution of melatonin. Greater penetration of melatonin through the cornea was demonstrated by ex vivo and in vivo tests. This can be attributable to an enhanced neuroprotective effect of melatonin on retinal ganglion cells when it is included in ethylcellulose nanocapsules compared to a solution of melatonin. These outstanding findings add promising new perspectives to current knowledge about administrations using nano-technological tools in the treatment of neurodegenerative diseases at the ocular level.

Do Ophthalmic Solutions of Amphotericin B Solubilised in 2-Hydroxypropyl-γ-Cyclodextrins Possess an Extended Physicochemical Stability?

Fungal keratitis is a sight-threatening disease for which amphotericin B eye drops is one of the front-line treatments. Unfortunately, there are currently no commercial forms available, and there is little data concerning the long-term stability of compounded formulations based on intravenous dosages forms. New formulations of amphotericin B ophthalmic solutions solubilised with γ-cyclodextrins have shown promising in-vitro results, but stability data is also lacking. The objective of this study was therefore to investigate the stability of a formulation of ready-to-use amphotericin B solubilised in 2-hydroxypropyl-γ-cyclodextrins (AB-HP-γ-CD), for 350 days. An amphotericin B deoxycholate (ABDC) formulation was used as a comparator. Analyses used were the following: visual inspection, turbidity, osmolality and pH measurements, amphotericin B quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. AB-HP-γ-CD formulation showed signs of chemical instability (loss of amphotericin B) after 28 and 56 days at 25 °C and 5 °C. Adding an antioxidant (ascorbic acid) to the formulation did not improve stability. ABDC formulation showed signs of physical instability (increased turbidy and amphotericin B precipitation) after 28 days and 168 days at 25 °C and 5 °C. As such, AB-HP-γ-CD formulation does not provide long-term stability for ophthalmic amphotericin B solutions.

Stability of Ophthalmic Atropine Solutions for Child Myopia Control

Myopia is an ophthalmic condition affecting more than 1/5th of the world population, especially children. Low-dose atropine eyedrops have been shown to limit myopia evolution during treatment. However, there are currently no commercial industrial forms available and there is little data published concerning the stability of medications prepared by compounding pharmacies. The objective of this study was to evaluate the stability of two 0.1 mg/mL atropine formulations (with and without antimicrobiobial preservatives) for 6 months in two different low-density polyethylene (LDPE) multidose eyedroppers. Analyses used were the following: visual inspection, turbidity, chromaticity measurements, osmolality and pH measurements, atropine quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. In an in-use study, atropine quantification was also performed on the drops emitted from the multidose eyedroppers. All tested parameters remained stable during the 6 months period, with atropine concentrations above 94.7% of initial concentration. A breakdown product (tropic acid) did increase slowly over time but remained well below usually admitted concentrations. Atropine concentrations remained stable during the in-use study. Both formulations of 0.1 mg/mL of atropine (with and without antimicrobial preservative) were proved to be physicochemically stable for 6 months at 25 °C when stored in LDPE bottles, with an identical microbial shelf-life.

Stability and Safety Traits of Novel Cyclosporine A and Tacrolimus Ophthalmic Galenic Formulations Involved in Vernal Keratoconjunctivitis Treatment by a High-Resolution Mass Spectrometry Approach

In this study, a sensitive quantitative method based on high performance liquid chromatography combined with high-resolution mass spectrometry, Q Exactive^TM-Orbitrap^® was set up and applied for the determination of the immunosuppressor agents cyclosporine A and tacrolimus in novel ethanol-free ophthalmic formulations for the treatment of Vernal keratoconjunctivitis. Different storage parameters in terms of storage temperatures and practical usage conditions were investigated to assess the stability of all formulations during shelf life simulating the real conditions as well to confirm the feasibility of use of ethanol-free products. The methodology was linear (r² = 0.995) over the concentration range 0–200 ng/mL, and its selectivity, precision, accuracy and recovery were all within the required limits. Under different conditions (storage period 0–90 days, 5–25 °C, unopened/usage simulated conditions), our results revealed that both active pharmaceutical ingredients (API) show satisfactory stability up to 30 days of storage/usage, with a significant and consistent concentration decline of cyclosporine A after this time point when its hydroalcoholic formulation was kept at 25 °C.

Solubilization of Cyclosporine in Topical Ophthalmic Formulations: Preformulation Risk Assessment on a New Solid Form

Owing to the discovery of a less soluble crystalline form (form 2) of cyclosporine (CsA), risks in solubility and physical stability of these formulations need to be revisited. This work focused on understanding the solubility behavior of various CsA forms in different media, including water, castor oil, and selected cosolvent micellar systems. In water, form 2 was approximately 8-9 times less soluble than form 1 (aka. tetragonal dihydrate). In neat nonaqueous solvent, for example, castor oil, form 3 (aka. orthorhombic hydrate) was found to have the lowest solubility and therefore the most stable form. In addition, the solubility-temperature relationship of CsA is complex and solvent-dependent. In aqueous vehicles, retrograde temperature dependence of solubility was observed in aqueous vehicles, that is, the solubility of CsA decreased with temperature, which was attributed to the effect of temperature on the strength of hydrogen bonding interactions; conversely, the solubility of CsA increased with temperature in nonaqueous solvents. In addition, the solubility of these CsA forms was very sensitive to temperature. Temperature-dependent form transformation was also observed in the media studied, with faster form conversion occurring at elevated temperatures. These studies provided key information to support the risk assessment for topical ophthalmic formulation development of CsA.

A Sorption Study between Ophthalmic Drugs and Multi Dose Eyedroppers in Simulated Use Conditions

Preservative free ophthalmic formulations need to be packaged either as single doses, or using specially designed sterility preserving multidose eyedroppers. Our objective was to evaluate potential sorption phenomena between a device with a silicone sterility preserving membrane and the delivered drops of several ophthalmic solutions. Cyclosporine, rifamycin, latanoprost, timolol and norfloxacin were used as model drugs. Quantification of the active substance in delivered drops (1 to 4 drops per day) from low density polyethylene (LDPE) bottles without any sterility preserving device and from LDPE bottles with a sterility preserving silicone membrane (LDPE-Si) was performed for 14 days (n≥3), using validated HPLC methods. For cyclosporine, mean concentrations did not vary by more than 10 % from reference concentrations for either LDPE or LDPE-Si eyedroppers, but for LDPE-Si, the concentrations of the 1 mg.ml-1 cyclosporine micellar solution were found to be significantly lower than for those from LDPE eyedroppers (p=0.0127). For LDPE-Si, rifamycin mean concentrations decreased by 11.2 % throughout the 14 day study period, but didn’t vary by more than 10 % for LDPE and glass eyedroppers. However, rifamycin concentrations from LDPE-Si were not significantly different from those from LDPE eyedroppers. For latanoprost, whilst mean concentrations did not vary by more than 10 % from reference concentration for LDPE eyedroppers, for LDPE-Si eyedroppers concentrations decreased by 76.4 % at their lowest concentration and never returned to their initial level. For timolol and norfloxacin, mean concentrations did not vary by more than 10 % for either LDPE or LDPE-Si eyedroppers and no significant difference was found between the 2 eyedroppers concentrations. Our results are in favor of an absence of significant sorption between LDPE-Si eyedroppers for timolol or norfloxacin ophthalmic solutions. Further studies should be performed on cyclosporine ophthalmic micellar solutions and rifamycin ophthalmic solutions before any definite conclusions can be made. Finally, our results show that latanoprost ophthalmic solutions shouldn’t be used with LDPE-Si eyedroppers as the loss of active substance would cause a sever under-dosing.