title: Efficacy of a Novel Prefilled, Single-Use, Needle-Free Device (Zeneo®) in Achieving Intramuscular Agent Delivery: An Observational Study.
abstract: It is recognized that, as a result of variation in tissue anatomy, current auto-injectors may have insufficient needle length to achieve successful intramuscular agent delivery in a number of patients. The Zeneo®auto-injector is a novel prefilled, single-use, needle-free device currently in development for intradermal, subcutaneous, and intramuscular agent delivery across a variety of clinical indications. We aimed to evaluate delivery depth of the device calibrated at pressure appropriate for intramuscular (IM) administration.
  
  
  
  This was a prospective single-center study in healthy adult volunteers, in whom each received a single injection of saline into the anterolateral thigh. Using sequential MRI scans, we measured skin-to-muscle distance (STMD) agent delivery depth, and the success of IM agent penetration. Device dynamic pressure measurements were also recorded.
  
  
  
  Results are reported for 37 subjects with evaluable MRI scans; 19 men, 18 women; mean age 38 years (range 20-58); mean BMI 27.0 kg/m2(range 21.2-30.8 kg/m2). Mean STMD values were 18.6 mm (range 13.4-23.6 mm) in women and 10.0 mm (range 5.0-21.7 mm) in men, with gender differences due primarily to greater subcutaneous thickness in women. A trend for greater STMD in subjects with BMI greater than 25 kg/m2was seen. Mean injectate penetration depths of 30.1 mm (range 20.2-45.6 mm) were observed with values similar in male and female subjects. Successful IM delivery was reported in 95% of subjects. When failure occurred, this was not due to inadequate injection depth. Device pressure (Pmax) had the greatest influence on injectate muscle penetration.
  
  
  
  Use of the Zeneo®auto-injector achieves delivery depth that ensures intramuscular delivery in both men and women, regardless of BMI. Consistent with other reported data, STMD is greater in women.
  
  
  
  Crossject.
authors.affiliation: Clinical Investigation Center (CIC) INSERM 1432, Dijon University Hospital, Dijon, France. Marc.bardou@u-bourgogne.fr.
authors.forename: Marc
authors.initials: M
authors.lastname: Bardou
authors.affiliation: Clinical Investigation Center (CIC) INSERM 1432, Dijon University Hospital, Dijon, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Luu
authors.affiliation: Le2i, UMR CNRS 6306 UFR Sciences de Santé Université de Bourgogne, Franche-Comté, Dijon, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Walker
authors.affiliation: Crossject, 60 L Avenue du 14 Juillet, 21300, Chenôve, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Auriel
authors.affiliation: Crossject, 60 L Avenue du 14 Juillet, 21300, Chenôve, France.
authors.forename: Xavière
authors.initials: X
authors.lastname: Castano
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D009339:Needles; D011446:Prospective Studies; D012867:Skin / Q000033:anatomy & histology; D013848:Thigh / Q000033:anatomy & histology
keywords: Anaphylaxis; Auto-injector; Epinephrine/adrenaline; Intramuscular; Needle length; Skin-to-muscle depth