Stability of reconstituted fluconazole oral suspension in plastic bottles and oral syringes

Fluconazole for oral suspension is a dry powder with a beyond-use date of 14 days after being reconstituted. Dispensing fluconazole liquid in the inpatient setting would be much more efficient if prefilled oral syringes containing standard doses were readily available. In addition, if the beyond-use date could be extended, the resulting decreased waste would be economically beneficial.

To determine the stability of reconstituted fluconazole oral suspension using high-performance liquid chromatography (HPLC).

Diflucan lyophilized powder was reconstituted to fluconazole 40 mg/mL using Sterile Water for Irrigation, USP. Samples were stored at room temperature in both the original Diflucan plastic bottles and in amber polyethylene oral syringes with silicon elastomer plunger tips that were sealed with high-density polyethylene caps. Samples were analyzed immediately and at 14, 28, 42, 56, and 70 days. Fluconazole concentrations were measured using a modified stability-indicating HPLC method. At each test interval, the density of the suspension was determined gravimetrically and then used to calculate the exact volume of sample used for each analysis. Excessive degradation was defined as greater than 10% loss of the initial concentration.

The stock internal standard was stable for at least 77 days when stored in the dark at room temperature. The stock and working fluconazole standard solutions were prepared fresh at each test interval. Reconstituted oral suspension retained more than 90% of the initial fluconazole concentration for at least 70 days at 22-25 degrees C. No changes in color, odor, or visible microbiological growth were observed in any sample. The pH of the suspension was initially 4.2 and remained essentially unchanged throughout the study.

Reconstituted fluconazole oral suspension is stable in both the product's original plastic bottles and in amber polyethylene oral syringes for at least 70 days when stored at 22-25 degrees C.