Engineering study comparing injection force and dose accuracy between two prefilled insulin injection pens

AbstractObjective:This study compared injection force (measured by glide force [GF] and glide force variability [GFV]) and dosing accuracy of the Humalog KwikPen* (prefilled insulin lispro [Humalog† pen, Eli Lilly and Company, Indianapolis, IN) and the Next Generation FlexPen‡ (prefilled insulin aspart [NovoRapid§ pen, Novo Nordisk A/S, Bagsværd, Denmark). * Humalog KwikPen is a registered trademark of Eli Lilly and Company, Indianapolis, IN, USA. † Humalog is a registered trademark of Eli Lilly and Company, Indianapolis, IN, USA. ‡ FlexPen is a registered trademark of Novo Nordisk A/S, Bagsværd, Denmark. § NovoRapid is a registered trademark of Novo Nordisk A/S, Bagsværd, Denmark. Research design and methods:A total of 100 prefilled insulin pens (50 insulin lispro pens, 50 insulin aspart pens) were tested using two dose sizes (30 U and 60 U). In all, 50 devices (25 of each type) were tested at 10 U/s dosing speed and 50 were tested at 6.6 U/s. Devices were used per manufacturer instructions. Dose accuracy (represented as absolute dose error %), maximum and average GF, and GFV data were automatically collected by the test system for all datasets (dose size/dosing speed/device type). The test system controlled for potential dosing errors.Results:The insulin lispro pen demonstrated a significantly lower median maximum GF at both dosing speeds: (2.83 vs. 3.92 lbs [30 U] and 3.00 vs. 4.14 lbs [60 U]) at 10 U/s; (1.85 vs. 2.93 lbs [30 U] and 2.14 vs. 3.02 lbs [60 U]) at 6.6 U/s, all p < 0.0001. For all datasets, the median GFV was significantly lower for the insulin lispro pen, p < 0.0001. Median dose error was comparable between device types when tested at 10 U/s dosing speed; however, at 6.6 U/s, the median dose error was significantly lower for insulin lispro pen compared to insulin aspart pen (0.47 vs. 0.67% [30 U] and 0.50 vs. 0.78% [60 U], both p < 0.05).Conclusions:The insulin lispro pen had significantly lower median GF and GFV compared with insulin aspart pen when tested at two dose sizes and two dosing speeds. Median dose error was similar between the device types at the 10 U/s dosing speed, but median dose error was significantly lower for the insulin lispro pen at the 6.6 U/s dosing speed. A limitation of this study was that it was executed as an open label study.Key words:: Dose accuracyGlide forceGlide force variabilityInjection forceInsulin pen TransparencyDeclaration of fundingThis study and resulant paper were funded by Eli Lilly and Company.Declaration of financial/other relationshipsAll authors have disclosed that they are employees and shareholders of Eli Lilly.Some peer reviewers receive honoraria from CMRO for their review work. Peer reviewer 1 of this paper has disclosed that he/she has received research support and consulting honoraria from Novo Nordisk, Lilly and several other pharmaceutical companies. The other reviewer has disclosed that he/she has no relevant financial relationships.AcknowledgmentThe authors express their appreciation to Amy Kornokovich, the Project Statistician, for assistance with the statistical data analysis.Notes* Humalog KwikPen is a registered trademark of Eli Lilly and Company, Indianapolis, IN, USA.† Humalog is a registered trademark of Eli Lilly and Company, Indianapolis, IN, USA.‡ FlexPen is a registered trademark of Novo Nordisk A/S, Bagsværd, Denmark.§ NovoRapid is a registered trademark of Novo Nordisk A/S, Bagsværd, Denmark.* Humalog, Humalog Mix25, Humalog KwikPen, and Humalog Mix25 KwikPen are trademarks of Eli Lilly and Company, Indianapolis, IN, USA.† NovoMix and FlexPen are registered trademarks of Novo Nordisk A/S, Bagsværd, Denmark.‡ Humalog KwikPen is a registered trademark of Eli Lilly and Company, Indianapolis, IN, USA.§ Humalog is a registered trademark of Eli Lilly and Company.** NovoRapid and FlexPen are registered trademarks of Novo Nordisk A/S, Bagsværd, Denmark.†† NovoFine is a registered trademark of Novo Nordisk A/S, Bagsværd, Denmark.