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.