Stability of an extemporaneously compounded terbutaline sulfate oral liquid

The stability of terbutaline sulfate in an extemporaneous oral liquid formulation refrigerated for 55 days was studied. A suspension was prepared by grinding commercially available 5-mg terbutaline sulfate tablets, adding Purified Water, USP, to form a paste, and then adding Simple Syrup, NF. A control solution was prepared from analytical grade terbutaline sulfate powder in Simple Syrup, NF. The final concentration of terbutaline sulfate in both preparations was 1 mg/mL. Three samples of each formulation were stored in 4-ounce amber glass prescription bottles in the dark at 4 degrees C. Immediately after preparation and at 10, 19, 35, and 55 days, samples were visually inspected, tested for pH, and assayed in duplicate by high-performance liquid chromatography. On days 0 and 35, 100-microL samples of each suspension and solution were placed on agar plates for microbiological testing. On day 55, the mean percentages of the initial terbutaline sulfate concentrations remaining were 103.8% in the suspension and 91.7% in the solution. Color, odor, and pH of the samples did not change appreciably, and colony counts of bacteria were within acceptable limits. An extemporaneously prepared liquid preparation of terbutaline sulfate in Simple Syrup, NF, is stable under the conditions studied for up to 55 days; however, since microbiological testing was not performed on day 55, it is recommended that the preparation be stored for no longer than 30 days.