Stability of Vancomycin 25 mg/mL in Ora-Sweet: DISCUSSION

7 Jan
2011

The lack of a commercially available vancomycin solution for oral administration poses problems for adults and children who are unable to swallow capsules. Until the time of this study, vancomycin oral liquid was prepared on an “as needed” basis by the pharmacy staff at Fraser Health. These solutions were given short expiration dates, and refrigeration was specified for storage. To the authors’ knowledge, there are no published stability studies for vancomycin oral solutions prepared in equal volumes of Ora-Sweet and distilled water.

In the serial analysis of samples reported here, no notable changes in colour, taste, or pH were observed for vancomycin solutions stored in unit-dose cups at 4°C and 25°C and in plastic bottles at 4°C throughout the 75-day period. A white precipitate was observed starting on day 63 in the plastic bottles stored at 25°C, but there were no notable changes in taste or pH for these samples during the 75-day period. Although the measures of physical characteristics (aside from pH) were qualitative, all observations were documented by the same individual throughout the study period, which eliminated interobserver bias. order levitra

On the basis of the 95% CI of the slope determined by linear regression, it is predicted that all vancomycin solutions stored in cups or bottles at 4°C will maintain at least 93.6% of their initial vancomycin concentration for 75 days, whereas solutions stored at 25°C will maintain at least 90.0% of their initial concentration for 30 days (cups) and 26 days (bottles), with 95% confidence.

The information from this study will allow for a variety of storage and distribution scenarios. Furthermore, vancomycin liquid prepared from the injectable form is less expensive than prepared from capsules. Specifically, the expiry date of 30 days for vancomycin oral liquid at room tem­perature is expected to significantly change manufacturing, storage, and distribution practices at the authors’ institution. Packaging vancomycin in the unit-dose cups will result in further improvements in patient safety, quality control, and operational efficiency.

One limitation of this study relates to freezing of the samples at —85°C until the time of batch analysis. It was assumed that vancomycin degradation would not occur at this low temperature and that there would be no volume losses due to freeze-drying during storage. It was also assumed that errors due to serial analysis would be greater than any errors associated with batch analysis. Furthermore, time 0 samples stored for 85 days at -85°C showed no degradation products and contained the expected concentration of vancomycin 25 mg/mL (see Figure 1A), yet samples stored for a shorter period of time at room temperature (e.g., 75 days) showed an additional degradation peak (see Figure 1B). These contrasting results provide evidence that storage at -85°C had no effect on the estimate of stability of vancomycin.  levitra professional

Before the study began, several recipes were tried, with various combinations of Ora-Plus, Ora-Sweet SF (sugar-free), and Ora-Sweet (all produced by Paddock Laboratories). The first 2 of these products caused clumping and were therefore abandoned in favour of Ora-Sweet. This sweetening vehicle was used in the current recipe because it not only dissolves well with reconstituted vancomycin for injection and distilled water but also improves the taste.

CONCLUSIONS

According to serial qualitative, pH, and HPLC analyses, vancomycin solutions 25 mg/mL stored in unit-dose cups or plastic bottles at 4°C were stable over a 75-day period, whereas those stored at 25°C are expected to be stable for up to 30 days (cups) and 26 days (bottles).

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