Impact of deep freezing on the stability of 25 mg/ml vancomycin ophthalmic solutions

Stability of 5% vancomycin ophthalmic solution prepared using balanced salt solution after freezing for 90 days

PURPOSE

To evaluate the stability of 5% vancomycin ophthalmic solution prepared using balanced salt solution (BSS) and stored at -20°C in polypropylene containers.

METHODS

Six batches of vancomycin 50 mg/mL eyedrops were aseptically prepared. One bottle of each batch was analyzed immediately after preparation, and the rest were stored at -20°C and analyzed using high-performance liquid chromatography (HPLC) at 30, 60, and 90 days to test their physicochemical stability and sterility. Thereafter, bottles were removed from the freezer and stored at 5°C for 30 days, with HPLC and other analyses repeated 105 and 120 days after preparation. All samples were analyzed in triplicate. Stability was defined as the absence of particles, color variation, or changes in pH and a remaining vancomycin concentration of 90% to 110% of the initial concentration. The sterility of the ophthalmic solution was evaluated by using soybean-casein digest broth with resins; samples were incubated for 7 days and checked daily for signs of microbial growth.

RESULTS

There was no particle formation or sign of precipitation in any of the solutions throughout the duration of the study, regardless of the storage conditions. No change in color or turbidity was observed. The pH and osmolarity remained unchanged during storage at -20°C and after thawing. The vancomycin concentration remained within 10% of the initial concentration during the 90-day period of storage at -20°C and the subsequent 30 days after thawing. Sterility was preserved in all samples.

CONCLUSION

A 5% solution of vancomycin prepared using BSS was physicochemically and microbiologically stable when stored at -20°C for 90 days. After thawing, this extemporaneous formulation remained stable when refrigerated at 5°C for 30 days.

Vancomycin Loaded Glycerol Monooleate Liquid Crystalline Phases Modified with Surfactants

The influence of two tuning agents, polyglycerol ester (PE) and triblock copolymer (TC), on the properties of glycerol monooleate (MO) liquid crystalline phase (LCP) was investigated to achieve the therapeutic concentration of vancomycin hydrochloride (VHCl) into the eye, topically during 60 min (1 h) and intravitreally during 2880 min (48 h). Different techniques were used to elucidate the impact of surfactants on the structure of the LCP: polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), and in vitro release tests I and II (simulating local and intravitreal application in the eye). The structure analysis by SAXS depicts that the inclusion of PE into the MO LCP provided partial transition of a hexagonal phase into a lamellar phase, and TC induced a partial transition of a hexagonal phase into an LCP which identification was difficult. The LCP modulated with PE and TC demonstrated different VHCl's release patterns and were evaluated by comparing our release data with the literature data. The comparison indicated that the LCP modulated with 30% w/w PE could be a promising VHCl delivery system intravitreally during 2880 min.

Terminalia arjuna gum/alginate in situ gel system with prolonged retention time for ophthalmic drug delivery

Poor availability is the major barrier to accept the new smart gel system as a preferred ophthalmic solution for various eye problems. Smart gel system especially derived from natural source allows the rapid transition of ocular solution into gel form upon contact to tear solution. The present experimental scheme was intended to prepare and characterize a pH triggered in situ gelling system using moxifloxacin HCl (MOX-HCl). Gum was extracted from Terminalia arjuna bark resin and used as gelling agent in blend with sodium alginate. Sterilized formulations were developed and characterized for their physicochemical attributes. These were further investigated for microbiological testing and eye irritation studies. Drug loaded in situ gel was appeared as clear sol that converted into gel phase in presence of tear solution. Optimized formulation was stable, therapeutically efficacious, non-irritant and has a sustained release of the drug for twelve hours period. Instillation of MOX-HCl loaded in situ gel did not cause any type of irritation symptoms like redness, inflammation and excessive tear production in rabbits as compared to control. MOX-HCl loaded in situ gel can be appraised as a substitute for conventional eye drops for extended precorneal retention, improved corneal permeability along with better ocular bioavailability.

Preserving the Efficacy of Glycopeptide Antibiotics during Nanoencapsulation in Liposomes

Liposome nanovesicles are attractive vehicles for encapsulation and localized delivery of antibiotics. Most liposomal batch preparation processes involve numerous freeze-thaw cycles and heating or sonication steps, all of which can potentially deactivate or degrade antibiotics. We investigated the extent of antibiotic deactivation during various liposomal preparation methods using two glycopeptide antibiotics clinically administered for Staphylococcus infections, namely, vancomycin hydrochloride and teicoplanin. Both antibiotics, in the nonencapsulated state, were found to be highly sensitive to the freeze-thaw/sonication; vancomycin completely lost efficacy after only three cycles of freeze-thaw, and teicoplanin lost efficacy after 20 min of sonication. When the antibiotics were encapsulated in liposomes, vancomycin retained full potency against bacterial cultures of Staphylococcus aureus but encapsulated teicoplanin suffered a decrease in activity. Differential scanning calorimetry and mass spectrometry suggest that liposomes have a protective effect on the encapsulated antibiotic, the extent of which was found to differ on the basis of the processing conditions.

Stability of a 50 mg/mL Ceftazidime Eye-Drops Formulation

Background

Microbial keratitis are severe infectionsgenerally linked to risk factors. High-doses antibiotic eye-drops could be required to avoid severe complications. In such cases, hospital pharmacists are in charge of their production given the lack of such formulations on the market. The stability of these antibiotic eye-drops is generally limited to a couple of days and publications generally do not describe addition of microbial preservatives even though it is a European Pharmacopeia requirement. The aim of this study was to describe a new ceftazidime eye-drops formulation at 50 mg/mL with a antimicrobial additive, benzalkonium chloride at 0.04 mg/mL.

Methods

Physico-chemical studies of this new formulation were performed by a stability indicating HPLC-UV method validated according to ICH standards, osmolality measurements, pH monitoring and visual examinations. Antimicrobial preservative efficacy was evaluated according to the method from the European Pharmacopeia.

Results

After 75 days at −20 °C followed by 7 days at 4 °C, or after 7 days at 4 °C, the eye-drops were stable. A degradation trend was finally observed at day 14 at 4 °C.

Conclusions

A new ceftazidime eye-drops formulation is proposed with a stability of 7 days. Outpatients do not need to return to the hospital pharmacy for repeat dispensing, thus possibly improving treatment compliance.

The Risk of Microbial Contamination in Multiple-Dose Preservative-Free Ophthalmic Preparations

Multiple-dose ophthalmic preparations that do not contain preservatives carry high risks of microbial contamination. However, there are various types of hospital preparations, with different physicochemical properties. In the present study, we evaluated the association between physicochemical properties and microbial contamination in ophthalmic preparations. The investigated hospital preparations included ophthalmic preparations of physiological saline, 0.2% fluconazole, 0.5% vancomycin hydrochloride, and 2% cyclosporine. We investigated the microbial dynamics of each ophthalmic preparation and microbial contamination in ophthalmic preparations used by patients. Remarkable growth of Pseudomonas aeruginosa, Burkholderia cepacia, and Serratia marcescens was observed in ophthalmic preparations of physiological saline and 0.2% fluconazole. All tested microorganisms displayed decreased counts after inoculation in 0.5% vancomycin hydrochloride. In 2% cyclosporine, all investigated microorganisms were below the limit of detection after inoculation for 6 h. The microbial contamination rates of ophthalmic preparations used by patients were 16.7% (3/18 samples) for 0.5% vancomycin hydrochloride and 0% (0/30 samples) for 2% cyclosporine. All detected contaminants in 0.5% vancomycin hydrochloride were Candida spp., one of which was present at a level of 1×10⁴ colony-forming units/mL. The storage method for in-use ophthalmic preparations should be considered on the basis of their physicochemical properties.

Nanoparticles laden in situ gelling system for ocular drug targeting

Designing an ophthalmic drug delivery system is one of the most difficult challenges for the researchers. The anatomy and physiology of eye create barriers like blinking which leads to the poor retention time and penetration of drug moiety. Some conventional ocular drug delivery systems show shortcomings such as enhanced pre-corneal elimination, high variability in efficiency, and blurred vision. To overcome these problems, several novel drug delivery systems such as liposomes, nanoparticles, hydrogels, and in situ gels have been developed. In situ-forming hydrogels are liquid upon instillation and undergo phase transition in the ocular cul-de-sac to form viscoelastic gel and this provides a response to environmental changes. In the past few years, an impressive number of novel temperature, pH, and ion-induced in situ-forming systems have been reported for sustain ophthalmic drug delivery. Each system has its own advantages and drawbacks. Thus, a combination of two drug delivery systems, i.e., nanoparticles and in situ gel, has been developed which is known as nanoparticle laden in situ gel. This review describes every aspects of this novel formulation, which present the readers an exhaustive detail and might contribute to research and development.

Development and clinical evaluation of clotrimazole-β-cyclodextrin eyedrops for the treatment of fungal keratitis

Fungal keratitis is a serious corneal disease that may result in loss of vision. There are limited treatment options available in Iraqi eye hospitals which might be the main reason behind the poor prognosis of many cases. The purpose of this study was to prepare and pharmaceutically evaluate clotrimazole-β-cyclodextrin (CTZ-β-CD) eyedrops then clinically assess its therapeutic efficacy on fungal keratitis compared with extemporaneous amphotericin B eyedrops (0.5% w/v). A CTZ-β-CD ophthalmic solution was prepared and evaluated by various physicochemical, microbiological, and biological tests. The prepared formula was stable in 0.05 M phosphate buffer pH 7.0 at 40 ± 2°C and 75 ± 5% RH for a period of 6 months. Light has no significant effect on the formula's stability. The CTZ-β-CD eyedrops efficiently complied with the isotonicity, sterility, and antimicrobiological preservative effectiveness tests. Results of the clinical study revealed that 20 (80%) patients showed a favorable response to the CTZ-β-CD eyedrops, while 16 patients (64%) exhibited a favorable response to amphotericin B (P > 0.05). The mean course of treatment was significantly (P < 0.05) less in the CTZ treatment group than in the amphotericin group (21.5 ± 5.2 vs. 28.3 ± 6.4 days, respectively). The CTZ formulation was significantly (P < 0.05) more effective in the management of severe cases and also against Candida sp. than amphotericin B. There was no significant difference (P < 0.05) between both therapies against filamentous fungi. The CTZ-β-CD formulation can be used alternatively to other ophthalmic antimycotic treatment options in developing countries where stability, cost, or efficacy is a limiting factor.

[Fortified antibiotic (vancomycin, amikacin and ceftazidime) eye drop stability assessment at -20 degrees C]

INTRODUCTION

Fortified antibiotic ophthalmic solutions are regularly administered as an immediate treatment for bacterial keratitis. Fortified antibiotics used to be self-prepared by nurses. To solve this problem, pharmacy staff studied the stability of three 5% solutions of vancomycin, amikacin, and ceftazidime prepared in aseptic conditions from parenteral antibiotic solutions.

MATERIAL AND METHODS

Solutions were frozen at -20 degrees C. Each solution were examined before storage and over a 75-day period. Ceftazidime and amikacin were diluted in 0.9% sodium chloride and vancomycin in 5% dextrose. Over a 75-day period, physical and pharmacological (absorbance spectra) properties and the sterility of each stock solution were studied.

RESULTS

The pH of amikacin (6.51), ceftazidime (6.47), and vancomycin (3.77) remained stable during the 75-day period. Osmolarities also remained stable (367, 488, and 351 mOsm/L, respectively). There were no significant differences in the concentration, osmolarity, and pH of the three antibiotic solutions before storage and after 75 days of freezing. Over a 75-day period, the stability of amikacin, ceftazidime, and vancomycin remained constant; no contamination was detected before storage and after 75 days.

CONCLUSION

Topical fortified antibiotic solutions can be stored for 75 days at -20 degrees C (15 days quarantine). After this time, these eye-drops should be stored at 4 degrees C and should be discarded after 3 days.

Prescrire les collyres fortifiés

Fortified preparations of ophthalmic antibiotics are made with commercially available antibiotics (parenteral or lyophilized preparations). These fortified eyedrops have two main advantages: the increase in the antibiotic concentration in the corneal stroma and the wide choice of available antibiotics. Fortified ophthalmic solutions are used in severe keratitis (large diameter, stroma infiltration, inflammation of the anterior chamber, old patient). The following associations are recommended: ticarcillin+gentamicin+vancomycin or cephazolin+amikacin since they provide a broad-spectrum antibiotic activity against the wide range of bacteria that may cause keratitis. The main toxicity of these preparations is the retardation effect of the epithelial-healing rate (aminoglycosides, vancomycin) and the corneal and conjunctival toxic effects (aminoglycosides). However, fortified antibiotic drops remain the standard therapy for severe bacterial keratitis, given their corneal penetration and the possibility of the synergic and combined effect of an antibiotic association.