title: Stability of U-500 regular insulin in prefilled syringes.
abstract: OBJECTIVE
  To evaluate the stability of U-500 regular insulin in prefilled syringes stored under refrigeration for up to 28 days.
  
  
  METHODS
  U-500 regular insulin was drawn up in 1 mL insulin syringes in a clean, nonsterile environment to emulate conditions of a patient's home. Samples were assayed using a stability-indicating reverse-phase high-performance liquid chromatography method immediately after preparation (day 0) and after 7, 14, 21, and 28 days under refrigeration. Before evaluation, all samples were diluted to a concentration of 40 units/mL in the starting mobile phase. Stability was determined by evaluating the percentage of the initial concentration remaining at each time point.
  
  
  RESULTS
  At least 93.3% of the initial U-500 insulin concentration remained throughout the 28-day study period, with no statistically significant changes in the amount remaining. The percent of initial concentration remained above 97% for the first 21 days of the study.
  
  
  CONCLUSIONS
  A prefilled syringe with U-500 regular insulin is stable for at least 28 days when stored under refrigeration. These data are similar to those reported for U-100 regular insulin, indicating that prefilling syringes with U-500 insulin is a safe and effective practice for patients who are unable to accurately draw up their own point-of-care doses.
authors.affiliation: Wegmans School of Pharmacy, St. John Fisher College, 3690 East Ave., Rochester, NY 14618, USA. mlull@sjfc.edu
authors.forename: Melinda E
authors.initials: ME
authors.lastname: Lull
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Piacentino
authors.forename: Andrea N
authors.initials: AN
authors.lastname: Traina
mesh_terms: D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D004355:Drug Stability; D004356:Drug Storage; D007004:Hypoglycemic Agents / Q000737:chemistry*; D007328:Insulin / Q000737:chemistry*; D012034:Refrigeration; D013594:Syringes; D013997:Time Factors
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin