October 7, 2015
Shaking Up Diabetes Care: Resuspending Insulin Pens Critical

Perugia, Italy—Here’s a case where a simple reminder from a pharmacist can make a dramatic difference in the effectiveness of a drug. Advising diabetes patients to follow directions and be sure to shake certain insulin pens before use can significantly improve their care, according to new research.

An Italian study, published recently in the journal Diabetes Care, emphasizes the importance of shaking a neutral protamine Hagedorn (NPH) insulin pen before subcutaneous injection. Failing to do that, warn researchers from Perugia University School of Medicine in Italy, can cause wide variations in insulin levels and potentially out-of-control blood sugar.

“Crystalline NPH insulin comes in a two-phase solution with either a solvent or a rapid-acting insulin (in premixed formulations) and needs adequate mixing for complete resuspension before injection,” study authors point out.

To test the effect, the study team assessed the pharmacokinetics (PK) and pharmacodynamics (PD) after subcutaneous injection of NPH insulin 0.35 units/kg at steady-state by pen either resuspended—achieved by tipping the insulin pen 20 times or nonresuspended—keeping the pen in fixed position, either horizontally or vertically and with the tip either up or down. The 11 study participants, average age 31.5, had long-term type 1 diabetes.

Results indicate that compared with resuspended NPH insulin, nonresuspended NPH insulin resulted in profound PK/PD differences. How it differed was affected by the position in which the nonresuspended pen had been held, with either reduced (horizontal and with the tip up) or increased (with the tip down) plasma insulin concentrations.

Study authors also said the duration of NPH insulin action with the nonresuspended pen was shorter when the tip was up and longer when the tip was down, compared to the resuspended device.

Insulin levels were found to vary by as much as 23%, with blood sugar control diverging by as much as 62% based on whether the insulin pen was properly shaken.

“Compared with resuspended NPH insulin, lack of resuspension profoundly alters PK/PD and may importantly contribute to day-to-day glycemic variability of type 1 diabetes,” they study concludes.

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