Discussion
Adsorption is a nonspecific phenomenon that occurs with every solid
particle. This phenomenon is particularly important with insulin,
because it alters the rate of drug delivery to patient, and finally
impacts glycemic control [18]. In order to minimize insulin loss due
to adsorption and optimal glycemic control, appropriate clinical
practices should be determined according to the rate of insulin adsorbed
to the bag and set used during infusion.
In this study, the insulin concentration rates of the samples taken from
PP bags at the 1st, 2nd, 4th, 12th, and 24th hours were determined as
95%, 98%, 98%, 95%, and 100%, respectively. Accordingly, it has
been shown that the rate of insulin adsorption to PP bags is at most
5%, and this rate decreases after the first hour of infusion. In a
study by Jakobson et al. it was shown that insulin adsorbed 10% to the
PP bag at the first hour of infusion, and then this rate was decreased
while insulin was administered at a rate of 1 ml/h. Similarly, the
maximum adsorption rate was achieved at the 1st hour and then reduction
was determined in both studies [10]. The difference between the
maximum adsorption rates is thought to result from the difference in
infusion rates. It is reported that the rate of adsorption increases
with a slower infusion rate [10,16-22].
The insulin concentration of the samples taken from the end tip of the
PVC infusion set, at the 1st, 2nd, 4th, 12th, and 24th hours were
detected as 43%, 40%, 30%, 21% and 35%, respectively. Accordingly,
it was seen that the adsorption rate of insulin to PVC set was 57% at
the 1st hour and 65% at the 24th hour. In the study conducted by Zahid
et al., it was shown that the adsorption rate of insulin to the PVC
neonatal tube was approximately 55% at 3 hours and 15% at 24 hours
[16]. It is thought that the high adsorption rate determined in our
study may be due to the surface area difference of the sets used in both
studies. In the study of Trissel et al., it was reported that the
24-hour adsorption rate of insulin to the PVC bag was 35%. However, in
Trissel’s study, the sample was taken from the PVC bag at the beginning
and after 24 hours storage, not during infusion [15]. Although the
methods of both studies are different, it has been shown that the
maximum adsorption rate was within the first 4 hours and then reduction
in this rate was detected. So, changing the bag every 4 hours, which is
frequently applied in clinical practice, leads to an increase in insulin
loss.
It is thought that changing PVC and PP bags every 24 hours is more
appropriate in terms of both preventing insulin loss and reducing
workload. Besides, economic advantages of changing insulin solution bag
every 24 hours versus 4 hours should be considered in terms of
minimization of manpower (time spend for administration frequency and
preparation), sources (bag and solution) and insulin loss. However, the
stability of the insulin solution is of concern when using the bags for
24 hours. Also, there is no information on the stability of the insulin
solution at room temperature in the package insert. As a result of the
analysis, the insulin solution has been shown to maintain its stability
for 24 hours at room temperature.