Stability of metoprolol tartrate injection 1 mg/mL undiluted and 0.5 mg/mL in 0.9% sodium chloride injection and 5% dextrose injection.

PURPOSE

The stability of metoprolol tartrate injection 1 mg/mL undiluted and 0.5 mg/mL in 0.9% sodium chloride injection and 5% dextrose injection was studied.

METHODS

Sample set A contained 50 mL of Metoprolol Tartrate Injection, USP, 1 mg/mL transferred directly from the vials. Sample set B contained 50 mL of metoprolol 0.5 mg/mL diluted with 0.9% sodium chloride injection, and sample set C contained 50 mL of metoprolol 0.5 mg/mL diluted with 5% dextrose. All samples were prepared in triplicate and stored at room temperature. The stability of the samples was analyzed in duplicate using stability-indicating high-performance liquid chromatography immediately after preparation and at 6, 12, 18, 24, and 30 hours. The samples were assessed for pH and inspected for color and visible precipitation changes. The stability of metoprolol was determined by evaluating the percentage of the initial concentration remaining at each time interval. Stability of the product was defined as retention of 90% of the initial concentration.

RESULTS

The mean +/- S.D. initial concentration in sample sets A, B, and C was 1.006 +/- 0.009 mg/mL, 0.498 +/- 0.002 mg/mL, and 0.499 +/- 0.002 mg/mL, respectively. Throughout the 30-hour study period, at least 99% of the initial concentration of metoprolol tartrate remained in all three preparations at all time points. No appreciable changes in pH occurred. No changes in color and no visible precipitate or microbial growth were detected.

CONCLUSION

Metoprolol tartrate injection 1 mg/mL undiluted and 0.5 mg/mL in 0.9% sodium chloride injection and 5% dextrose injection were stable at room temperature for at least 30 hours.