Stability of levodopa in 5% dextrose injection at pH 5 or 6
Stennett, D.J.; Christensen, J.M.; Anderson, J.L.; Parrott, K.A.
American Journal of Hospital Pharmacy 43(7): 1726-1728
1986
ISSN/ISBN: 0002-9289 PMID: 3752109 Document Number: 283964
The stability of solutions of levodopa 1 mg/mL in 5% dextrose injection adjusted to pH 5 or 6 and stored at one of three temperatures was determined. Solutions were adjusted to pH 5 or 6 with sodium acetate injection or sodium phosphate injection, respectively. Three samples of solution adjusted to pH 5 were stored at each of three temperatures (4, 25, and 45 degrees C), and three samples of solution adjusted to pH 6 were stored at 25 degrees C. Samples were assayed for levodopa concentration by high-performance liquid chromatography at various times during the 21-day study period. All solutions maintained at least 90% of the initial concentration of levodopa for seven days. Discoloration of all solutions except those stored at 4 degrees C was noted at some point during the study period; solutions stored at 45 degrees C began to darken within 12 hours. The pH values of the solutions did not change during the study period. Under the conditions studied, solutions of levodopa 1 mg/mL in 5% dextrose injection adjusted to pH 5 or 6 are stable for seven days. Slight degradation of levodopa may cause a brownish-black discoloration of the admixtures.