Impact of carrier solution on biological insulin availability

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Objectives

When added into all-in-one (AIO) bags, total needs of exogenous insulin decrease compared to amounts given by perfusor. We studied the influence of carrier solution on insulin availability.

Materials and methods

A 20 ml polyvinylchloride (PVC) syringe was filled either with saline or AIO solution aspirated from original 3 l bags (Nutrimix, Brown, Melsungen, Germany). Then 8 IU of insulin (Actrapid HM, NovoNordisk, DK) was added into syringes (calculated concentration 400 IU × l ^-1) and a PVC perfusion line (5 ml volume) was filled. Baseline samples (0.5 ml) for immunoreactive insulin assay (IRI) were taken. Perfusor rate was set at 2 ml×hr^-1 and samples taken directly from the hose at 5, 10, 30, 60, 90 and 210 min, placed on ice and stored at 4°C before analysis. Fifteen sets of measurements were done both for saline and AIO solution. Values are presented as means ± SD. MANOVA, ANOVA for repeated measures and paired T-test with Bonferroni correction were used when appropriate; P<0.05 was considered significant.

Results

Figure 1 shows IRI concentrations in both saline and AIO solutions during the experiment.

IRI differed significantly giving higher IRI yield in AIO solution compared to saline (MANOVA group by time effect P<0.001). Changes in IRI concentration depending on time was seen in saline only (ANOVA time effect P<0.001 for saline; P=0.26 for AIO). When separate time points for saline were analyzed major changes were seen at the very beginning of the experiment (a decrease from 206± 34 at baseline to 152± 33 IU^*l^-1 at 5 min; P<0.001). The mean yield of IRI expressed as ratio of measured to calculated concentration at baseline was 0.52 for saline and 0.70 for AIO.

Figure 1

Conclusion

Insulin bioavailability in AIO solution is better than in saline with respect to the yield and stability.