title: Stability of U-10 and U-50 dilutions of insulin lispro.
abstract: BACKGROUND
  Insulin lispro, a rapid acting analog of human insulin, has been shown to be useful in the treatment of children with diabetes. However, lower concentrations of this insulin may be needed to facilitate optimal clinical use. Therefore, the stability of insulin lispro when diluted with an appropriate diluent was evaluated.
  
  
  METHODS
  Insulin lispro (U-100, 100 U/mL) was diluted with sterile Neutral Protamine Hagedorn (NPH) diluent to U-10 and U-50. After storage for 7, 14, 21, 28, and 32 days at 5 degrees C and 30 degrees C, the diluted insulins were analyzed by high-performance liquid chromatography (HPLC) to determine potency, purity, polymer, and preservative (metacresol or phenol) content in addition to physical appearance and pH determinations. Microbiological testing for preservative effectiveness was performed on the U-10 and U-50 solutions after 32 days at both temperatures.
  
  
  RESULTS
  U-10 and U-50 dilutions of insulin lispro stored at 5 degrees C and 30 degrees C maintained potency and purity throughout the 32-day testing period. Additionally, both control and diluted vials maintained antimicrobial effectiveness.
  
  
  CONCLUSIONS
  Insulin lispro when diluted with the appropriate diluent demonstrates acceptable stability when stored at 5 degrees C and 30 degrees C for a period of 32 days.
authors.affiliation: Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, USA. stickelmeyer_mary_P@lilly.com
authors.forename: M P
authors.initials: MP
authors.lastname: Stickelmeyer
authors.forename: C J
authors.initials: CJ
authors.lastname: Graf
authors.forename: B H
authors.initials: BH
authors.lastname: Frank
authors.forename: R L
authors.initials: RL
authors.lastname: Ballard
authors.forename: S M
authors.initials: SM
authors.lastname: Storms
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000031:analogs & derivatives / Q000032:analysis*; D061268:Insulin Lispro; D019999:Pharmaceutical Solutions / Q000032:analysis; D019800:Phenol / Q000032:analysis; D011479:Protamines; D013997:Time Factors
chemical_list: D007328:Insulin; D061268:Insulin Lispro; D019999:Pharmaceutical Solutions; D011479:Protamines; D019800:Phenol