Design and Comparative Evaluation of Vancomycin HCl-Loaded Rosin-Based In Situ Forming Gel and Microparticles

Vancomycin hydrochloride (HCl) is a glycopeptide antibiotic used to treat serious or life-threatening infections, and it reduces plaque scores and gingivitis in periodontal patients. In this study, vancomycin HCl was incorporated into rosin in situ forming gel (ISG) and rosin in situ forming microparticles (ISM) to generate a local drug delivery system to treat periodontal disease. The physical properties of the ISG and ISM were measured, including pH, viscosity, injectability, adhesion properties, in-vitro transformation, and drug release. Moreover, the effectiveness of antimicrobial activity was tested using the agar-cup diffusion method against Staphylococcus aureus, Streptococcus mutans, Porphyromonas gingivalis, and Escherichia coli. Vancomycin HCl-loaded rosin-based ISG and ISM had a pH value in the range of 5.02−6.48 and exhibited the ease of injection with an injection force of less than 20 N. Additionally, the lubricity effect of the external oil phase of ISM promoted less work of injection than ISG and 40−60% rosin-based ISM showed good emulsion stability. The droplet size of emulsions containing 40%, 50%, and 60% rosin was 98.48 ± 16.11, 125.55 ± 4.75, and 137.80 ± 16.8 µm, respectively. Their obtained microparticles were significantly smaller in diameter, 78.63 ± 12.97, 93.81 ± 10.53, and 118.32 ± 15.61 µm, respectively, because the particles shrank due to the solvent loss from solvent exchange. Moreover, increasing the concentration of rosin increased the size of microparticles. After phase transformation, all formulations had better plasticity properties than elasticity; therefore, they could easily adapt to the specific shape of a patient’s gum cavity. Both developed ISG and ISM presented inhibition zones against S. mutans and P. gingivalis, with ISG presenting significantly more effectively against these two microbes (p < 0.05). The vancomycin HCl-loaded rosin ISG and ISM delayed drug release for 7 days with efficient antimicrobial activities; thus, they exhibit potential as the drug delivery systems for periodontitis treatment.

Stability Evaluation of Extemporaneously Compounded Vancomycin Ophthalmic Drops: Effect of Solvents and Storage Conditions

Vancomycin is the drug of choice for methicillin-resistant Staphylococcus aureus keratitis and other ocular infections. Vancomycin ophthalmic drops are not commercially available and require compounding. The present study was designed to investigate the stability of vancomycin ophthalmic drops in normal saline, phosphate-buffered saline (PBS), and balanced salt solution (BSS) while stored at room temperature or under refrigeration. Vancomycin ophthalmic drops (50 mg/mL) were aseptically prepared from commercially available intravenous powder using PBS, BSS, and saline. Solutions were stored at room temperature and in a refrigerator for 28 days. The vancomycin stability was tested by a microbiology assay and high-performance liquid chromatography HPLC analysis immediately after formulation and at days 7, 14, and 28 after storage at room temperature or under refrigeration. The pH, turbidity was also tested. Vancomycin formulations in PBS, BSS and normal saline had initial pH of 5; 5.5; 3 respectively. The formulation in PBS developed turbidity and a slight decrease in pH upon storage. Microbiological assay did not show any change in zone of inhibition with any of the formulation upon storage either at room temperature or under refrigeration. HPLC analysis did not detect any decrease in vancomycin concentration or the accumulation of degraded products in any of the formulations upon storage either at room temperature or under refrigeration. Vancomycin ophthalmic drops prepared using PBS, BSS, and normal saline were stable up to the tested time point of 28 days, irrespective of their storage temperature.

Physicochemical Stability of Vancomycin at High Concentrations in Polypropylene Syringes

BACKGROUND

In severe infections, high-concentration vancomycin may be administered by continuous infusion. The dosage of vancomycin may reach 60 mg/kg per day.

OBJECTIVES

To study the feasibility of preparing high-concentration vancomycin solutions (40 to 83.3 mg/mL), to study the effect of an electric syringe pump on the physical stability of high-concentration vancomycin, and to study the stability of vancomycin 62.5 and 83.3 mg/mL in 0.9% sodium chloride (0.9% NaCl) or 5% dextrose in water (D5W) with storage up to 48 h at room temperature.

METHODS

The following sets of syringes were prepared: (1) 4 syringes of vancomycin in 0.9% NaCl for each of 5 concentrations between 40 and 83.3 mg/mL (total 20 syringes); (2) 6 syringes at 83.3 mg/mL in 0.9% NaCl and 6 syringes at 83.3 mg/mL in D5W; and (3) 30 syringes at 83.3 mg/mL in D5W. Visual inspection was performed for all 3 syringe sets, and subvisual inspection for sets 1 and 2 (for periods of 24 h for set 1 and 48 h for sets 2 and 3). One syringe of vancomycin 83.3 mg/mL with each solvent was inserted into an electric syringe pump, and samples from the infusion line and collected after transit through the pump were inspected visually. Chemical stability was evaluated by high-performance liquid chromatography, and physical stability, pH, and osmolality were investigated.

RESULTS

For all sets of syringes, no physical modification was observed over time, nor were any changes observed after transit through the electric syringe pump. In 0.9% NaCl, vancomycin 62.5 and 83.3 mg/mL retained more than 90% of the initial concentration after 48 and 24 h, respectively; however, for the 83.3 mg/mL solution, precipitate was visible after 48 h. In D5W, vancomycin at 62.5 and 83.3 mg/mL retained more than 90% of the initial concentration after 48 h.

CONCLUSION

It was feasible to prepare high-concentration solutions of vancomycin. The electric syringe pump did not cause any precipitation. Vancomycin in D5W at 62.5 and 83.3 mg/mL was stable over 48 h at room temperature. Precipitation occurred in 0.9% NaCl. D5W is therefore recommended as the solvent for this drug.