title: Dosing accuracy of two insulin pre-filled pens.
abstract: OBJECTIVE
  This study was designed to determine the dose accuracy of two commonly available insulin pre-filled pens for use in diabetes - FlexPen (Novo Nordisk A/S, Bagsvaerd, Denmark) (FP) and SoloStar (Sanofi-Aventis, Paris, France) (SS).
  
  
  METHODS
  Dosing accuracy was tested at 5 U, 10 U and 30 U doses - three previously unused pens of both pre-filled pens were used for each dose. At the 5 U dose each pen was tested 42 times, at the 10 U dose each pen was tested 25 times and at the 30 U dose each pen was tested 9 times. The pre-filled pens were used strictly according to manufacturers' instructions and measurements were made on a sensitive balance and corrected for the specific density of the insulin formulations used. Specified limits were based on ISO standards (+/-1 U for the 5 U and 10 U doses and +/-1.5 U for the 30 U dose).
  
  
  RESULTS
  FP was more accurate for injecting 5 U, 10 U and 30 U doses (absolute mean 4.95 +/- 0.19 U, 9.61 +/- 0.27 U and 29.70 +/- 0.34 U, respectively) than SS (absolute mean 4.86 +/- 0.39 U, 9.27 +/- 0.52 U and 28.73 +/- 0.47 U, respectively). No doses were outside specified limits for 5 U and 30 U with FP and 1.3% of doses were outside these limits at the 10 U dose. For SS; 1.6%, 29.3% and 33.3% of doses were below the pre-specified threshold for the 5 U, 10 U and 30 U doses, respectively.
  
  
  CONCLUSIONS
  This non-blinded comparison indicates that FP is a more accurate insulin pre-filled pen than SS at three different insulin doses. In this single-user study, FP delivered consistent and accurate doses of insulin but SS had a high frequency of under dosing. No assessment was made of user variability in this study.
authors.affiliation: Department of Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan. asa-mac@m7.dion.ne.jp
authors.forename: Toshinari
authors.initials: T
authors.lastname: Asakura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Seino
authors.forename: Miho
authors.initials: M
authors.lastname: Kageyama
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yohkoh
mesh_terms: D003920:Diabetes Mellitus / Q000175:diagnosis / Q000188:drug therapy*; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis / Q000188:drug therapy; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D004869:Equipment Safety; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous / Q000295:instrumentation*; D007328:Insulin / Q000008:administration & dosage*; D007332:Insulin Infusion Systems; D008297:Male; D011336:Probability; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013594:Syringes
chemical_list: D007328:Insulin