Off-Label Antibiotic Preparation

An Exploratory Study of a New Vancomycin Eye Drops Formulation for Extemporaneous Compounding

Purpose

Compounded eye drop solutions of vancomycin hydrochloride have important clinical applications, such as postoperative antimicrobial prophylaxis and bacterial keratitis. There exists a plethora of data to support the use of various liquid vehicles to compound vancomycin hydrochloride eye drops. However, there are a number of limitations for implementation, especially the frequent shortage or discontinuation of the vehicle products. This study was designed to investigate the use of an OTC eye wash product as the evergreen vehicle and to evaluate the physical and chemical stability of the new formulation.

Methods

The Advance Eye Relief^® eye wash and vancomycin hydrochloride for injection vials were used to prepare 10 and 50 mg/mL vancomycin eye drop solutions. The solutions were packaged in Steri-Droppers^® bottles and stored in a freezer for 14 days followed by 28 days in refrigeration. The 14-day period of freezing was included to allow time for sterility testing. At pre-determined stability time points, samples were taken for visual inspection, pH and osmolality measurement, and analysis by a stability-indicating high performance liquid chromatography (HPLC) method.

Results

Freshly prepared vancomycin eye drops were clear, colorless, and free of particulates. The pH readings were 7.03 and 6.28 for the 10 and 50 mg/mL solutions, respectively. The osmolality of both solutions were within the range of 300-330 mOsmol/kg and considered isotonic. Initial drug concentrations of all samples were confirmed by HPLC to be within 100%-103% of the label claims. Throughout the stability study period, there were no significant changes in the appearance, pH, or osmolality of any samples. The HPLC results also confirmed that the drug concentrations in all stability samples were within 98%-101% of the initial time zero values and no significant degradation product peaks were observed.

Conclusion

A new compounded vancomycin eye drop formulation was developed to mitigate vehicle sourcing issues. This eye drop formulation was easy to prepare, exhibited satisfactory properties for ophthalmic applications, and remained stable chemically and physically when stored for 14 days in freezer followed by 28 days in refrigerator.

Long-term potency, sterility, and stability of vancomycin, ceftazidime, and moxifloxacin for treatment of bacterial endophthalmitis

PURPOSE

To determine the long-term potency, sterility, and stability of vancomycin, ceftazidime, and moxifloxacin prepared in single-use polypropylene syringes for intravitreal injection.

METHODS

Experimental study. Vancomycin 1 mg/0.1 mL, ceftazidime 2 mg/0.1 mL, and moxifloxacin 160 μg/0.1 mL were compounded and prepared in 1-mL polypropylene syringes and stored at 4 °C, -20 °C, and -80 °C. Antibiotic potency, sterility, pH, osmolality, and concentration were tested at baseline and at 1, 2, 4, 8, 12, and 24 weeks after preparation.

RESULTS

Potency, sterility, and stability were preserved for all 3 antibiotics at all temperatures out to 24 weeks, although there was a trend toward reduced potency at Week 24 for vancomycin and ceftazidime stored at 4°C. The largest zones of inhibition for Staphylococcus epidermidis and S. aureus were consistently demonstrated by moxifloxacin.

CONCLUSION

Vancomycin, ceftazidime, and moxifloxacin prepared in single-use polypropylene syringes retain potency, sterility, and stability out to 24 weeks when stored at -20 °C or -80 °C. The results of this study may have important implications for the current management of endophthalmitis.