Objective: The present study aimed to assess the dosing accuracy of commonly used disposable insulin pens including SoloStar (SR)*, FlexPen (FP) dagger, Next Generation FlexPen (NGFP) dagger, and KwikPen (KP) double dagger. It is the first comparative study covering the whole dosing range from 1 U to 60 U. It also covers the accuracy of SR at 80 U.
Research design and method: A total of sixty insulin pens from two lots of each pen type were used. From each pen 1 U, 10 U, 30 U, 40 U, 60 U and 80 U were dispensed in random order. The 80 U dose was only evaluated for the SR as the other insulin pens do not deliver this dose in one injection. The actual doses were determined gravimetrically taking density of the different insulin preparations into account. The evaluation of dose accuracy was based on the regulations of the International Organization for Standardization (DIN EN ISO 11608-1:2000).
Results: All tested insulin pens met the requirements for accuracy with none of the single values at all dose levels being outside the defined range of the ISO recommendations (1 +/- 1 U, 10 +/- 1 U, 30 +/- 1.5 U, 40 +/- 2 U, 60 +/- 3 U and 80 +/- 4 U). For the investigated dosage levels the absolute average deviation of all insulin pens ranged between 0.09 and 0.81 U.
Conclusion: The present study demonstrates an excellent dosing accuracy for all tested insulin pens, with no clinically relevant differences between the products.