Oral vancomycin is a first-line treatment for Clostridium difficile-associated diarrhea. Preparation of oral vancomycin solutions historically has been facilitated by extemporaneous compounding, using various formulas or compounding kits, such as FIRST® - Vancomycin. More recently, FIRVANQ™ (vancomycin HCl) for oral solution was approved by the FDA, replacing the FIRST® compounding kits. Preparation and storage of unit-doses of oral solutions can expedite delivery of the medication to the patient and reduce opportunity for dosing errors. In this study, we evaluated the stored stability of two preparations of vancomycin HCl oral solution (FIRST® – Vancomycin and FIRVANQ™), stored in oral syringes and dosing cups at refrigerated and room temperatures.
Triplicate batches of vancomycin HCl oral solution (50 mg/mL) were prepared using FIRST® - Vancomycin and FIRVANQ™, aliquoted into plastic oral syringes and sealed dosing cups, and stored at refrigerated and room temperatures for a total of six batches. Additionally, remaining samples from FIRVANQ™ batches were unit-dosed in clear Luer-Lok™ syringes and stored under refrigeration as a seventh batch. Samples were removed and analyzed for vancomycin recovery using a previously validated high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method over a 30-day period. Recovery was quantitatively assessed by comparing to a freshly prepared United States Pharmacopoeia (USP) reference standard on each day of sampling.
Stability was defined as recovery of 90 - 110% of labeled amount. For all tested samples, the chemical potency remained within the therapeutically acceptable window for the entire study period of 30 days. At room temperature, the FIRST® syringes and cups both retained 95% potency after 30 days. Under refrigeration, this product retained 100% potency and 91% potency in syringes and cups, respectively. Similarly, the FIRVANQ™ room temperature syringes were at 99% recovery and the room temperature cups at 95% recovery after 30 days. Refrigerated FIRVANQ™ retained a potency of 102% potency in the dosing cups after 30 days, and the both syringes types (clear and amber) were 97% and 101%, respectively, recovery during the study period.
The percent recovery of vancomycin in each test group remains within 90 – 110% of the labeled amount throughout duration of study (0 – 30 days). Based on this study, unit-dosing has been shown to have a 30-day chemical stability. In this case, unit-dosing not only may be used to improve workflow and reduce dosing errors, but may also have an impact of reducing drug waste due to avoidance of discarding appropriately potent drug product. Additionally, stability within the study period was independent of storage container and condition. Finally, this unit-dosing practice for FIRVANQ™ is equally acceptable in the classic luer-slip amber plastic syringes, and the newer Luer-Lok™ clear plastic syringes.
Paul Lewis– Clinical Pharmacy Specialist, Johnson City Medical Center, Johnson City, Tennessee