Adsorption of insulin onto infusion sets used in adult intensive care unit and neonatal care settings

Comparative Study of Sorption Phenomena Between Three Medications and Syringes Made of Cyclic Olefin Copolymer or Polypropylene

INTRODUCTION

Medical syringes are widely used in hospitals to store and administer drugs, and the contact time between the drugs and these syringes can vary from a few minutes to several weeks like for pharmaceutical preparations. The aim of this comparative study was to evaluate the potential sorption phenomena occurring between three drugs (paracetamol, diazepam and insulin aspart) and polypropylene syringes (PP) or syringes made of Cyclic Olefin Copolymer (COC).

MATERIALS AND METHODS

50 mL 3-part syringes made of either COC with crosslinked silicone on the barrel inner surface (COC-CLS) and a bromobutyl plunger seal, or PP lubricated with silicone oil (PP-SOL) with a polyisoprene plunger seal were used.

RESULTS

COC-CLS syringes induced less sorption of diazepam and insulin than PP-SOL syringes and the plunger seal material seemed to be the main cause of these interactions. An alkalinization of the medications in contact with the PP-SOL syringes was observed. It could be caused by leachable compounds and should be investigated further.

CONCLUSION

This work shows once again that it is essential to consider content-container interactions to help improve the safe use of parenteral drugs.

Comparative study between a gravity-based and peristaltic pump for intravenous infusion with respect to generation of proteinaceous microparticles

Subvisible particles generated during the preparation or administration of biopharmaceuticals might increase the risk of immunogenicity, inflammation, or organ dysfunction. To investigate the impact of an infusion system on the level of subvisible particles, we compared two types of infusion set based on peristaltic movement (Medifusion DI-2000 pump) and a gravity-based infusion system (Accu-Drip) using intravenous immunoglobulin (IVIG) as a model drug. The peristaltic pump was found to be more susceptible to particle generation compared to the gravity infusion set owing to the stress generated due to constant peristaltic motion. Moreover, the 5-µm in-line filter integrated into the tubing of the gravity-based infusion set further contributed to the reduction of particles mostly in the range ≥ 10 µm. Furthermore, the filter was also able to maintain the particle level even after the pre-exposure of samples to silicone oil lubricated syringes, drop shock, or agitation. Overall, this study suggests the need for the selection of an appropriate infusion set equipped with an in-line filter based on the sensitivity of the product.

Adsorption of insulin onto neonatal infusion sets: should intravenous administration of insulin to treat hyperglycemia in preterm babies on the NICU be proceeded by priming of the intravenous system, adding of albumin, or non-priming to get to a stable insulin dose?

Insulin is used to treat neonatal hyperglycaemia when blood glucose concentrations are consistently high, and to treat neonatal diabetes. Within this brief report, a review of the existing literature is conducted to determine if intravenous administration of insulin should be proceeded by priming of the intravenous system, adding of albumin, or non-priming to get a stable insulin dose. Within this literature search, we focused on experimental insulin adsorption data (in vitro studies).

Insulin Adsorption onto PE and PVC Tubings

We investigate the adsorption of insulin onto PE and PVC materials by using HPLC measurements and computer simulations. We interpret the experiments by calculating the Gibbs free energy profiles during the adsorption process. The values of free energy of adsorption show a good agreement with the experimental measurements. The adsorption of insulin onto the different materials is characterized through the conformational changes with respect to its conformation in water and the interfacial regions, which are described by specific arrangements of polymer chains, water, insulin, and plasticizer molecules.

Critical Drug Loss Induced by Silicone and Polyurethane Implantable Catheters in a Simulated Infusion Setup with Three Model Drugs

Silicone and polyurethane are biocompatible materials used for the manufacture of implantable catheters, but are known to induce drug loss by sorption, causing potentially important clinical consequences. Despite this, their impact on the drugs infused through them is rarely studied, or they are studied individually and not part of a complete infusion setup. The aim of this work was to experimentally investigate the drug loss that these devices can cause, on their own and within a complete infusion setup. Paracetamol, diazepam, and insulin were chosen as models to assess drug sorption. Four commonly used silicone and polyurethane catheters were studied independently and as part of two different setups composed of a syringe, an extension set, and silicone or polyurethane implantable catheter. Simulated infusion through the catheter alone or through the complete setup were tested, at flowrates of 1 mL/h and 10 mL/h. Drug concentrations were monitored by liquid chromatography, and the silicone and polyurethane materials were characterized by ATR-IR spectroscopy and Zeta surface potential measurements. The losses observed with the complete setups followed the same trend as the losses induced individually by the most sorptive device of the setup. With the complete setups, no loss of paracetamol was observed, but diazepam and insulin maximum losses were respectively of 96.4 ± 0.9% and 54.0 ± 5.6%, when using a polyurethane catheter. Overall, catheters were shown to be the cause of some extremely high drug losses that could not be countered by optimizing the extension set in the setup.

Impact of insulin adsorption in various containers during hyperkalaemia treatment

Background

Insulin–glucose therapy in hyperkalaemia treatment has a narrow therapeutic index for a safe and efficient use. We assess the variability of the effective delivered insulin under conditions used in the setting of hyperkalaemia treatment.

Methods

A range of simulated insulin infusions was studied using different containers (bag or syringes) according to the different hyperkalaemia treatment procedures of our institution. Insulin concentration was assayed using a chromatographic method on an automatic high-performance liquid chromatography. We calculated the effective delivered insulin and compared the time average of percentage delivered insulin (TAdi) between all the procedures.

Results

The TAdi was significantly decreased to 63.3% of the expected insulin delivery in the polyurethane (PE) bag compared with allover container. The procedure duration and the insulin concentration influenced the variability of the insulin delivery in the PE and glass bag. The polyvinyl chloride bag had the highest TAdi at 93.8%, without significant variation during the time. TAdi reaches ∼90% of the expected insulin with all the syringe procedure without variation according to the solute used to dilute insulin.

Conclusions

Clinically significant variations in intravenous insulin delivery occur in the setting of hyperkalaemia treatment according to the container. The use of propylene syringe limits the insulin delivery variation. In the future, clinical studies on hyperkalaemia treatment by insulin–glucose therapy should detail the procedure precisely.

[Infusion sets in neonatology: What practices in France?]

OBJECTIVES

Therapeutic management of ill newborns can require complex infusion practices using medical devices (MD). Currently, there does not exist any recommendations concerning these infusion practices. The objective of this work was to study and characterise French infusion methods neonatal and neonatal intensive care units.

MATERIALS AND METHODS

The study was performed in 2019, during 6 months. French hospitals possessing high (type 3) or medium (type 2B) grade maternity ward were contacted and asked to complete a 5 part online survey, to gather general information about the hospital/ward, infusion methods (overall and detailed), and detailed information about the medications and MD used.

RESULTS

The participation level was of 19.6 % Type 3 maternities use overall two-times more MD than those of type 2B. The vascular access device most commonly used was a single lumen catheter (80.6 % of infusion methods). 100 % of the hospitals having answered used multi-access devices (three-way tap, multiport infusion manifold, Y-extension lines) and 93.5 % used a pump-infusor. Lipidic filters for parenteral nutrition were used in 78.6 % of the hospitals. Two general standard of infusion methods were isolated: a simple version with two access points (type 2B hospitals), and a complex one with five access points (from hospitals with type 3 maternities).

CONCLUSIONS

Neonatal infusion practices in France are very heterogeneous, thus exposing the patients to a degree of variability during their therapeutic management. This work is a first step forwards to help analyse and anticipate the risks of content/container interactions caused by infusion practices.

Clinical Recommendations for Managing the Impact of Insulin Adsorptive Loss in Hospital and Diabetes Care

BACKGROUND

Adsorption of insulin to infusion sets impacts patient therapeutic outcomes and, unaccounted for, may exacerbate persistent hyperglycemia or result in therapy-induced hypoglycemia. This article aims to provide recommendations for clinicians involved in intensive care and/or outpatient pump therapy contexts.

METHODS

A dynamic adsorption model is used to evaluate time-varying insulin concentration in the infusion set outflow. Hourly and daily percentage insulin loss to adsorption is examined for neonatal, pediatric, and adult intensive care patients, as well as outpatient children and adults weighing 30, 50, and 80 kg. A short review of preconditioning methods is included.

RESULTS

Insulin adsorption in outpatient pump therapy is most pronounced in the first hour, where as much as 80% of the intended insulin dose may be lost to adsorption. Subsequently, insulin adsorptive loss is typically negligible. Overall, extra care should be taken in the first 1-6 h of a new infusion set, particularly in children or teenagers. Typically, insulin adsorption in the adult intensive care unit is negligible unless infused at low flow rates (<2 mL/h). Insulin adsorption is significant in pediatric and neonatal intensive care, resulting in delivery concentrations as low as 5%-50% of that intended. Thus, it is recommended that preconditioning of insulin delivery lines be carried out prior to infusion initiation in this context. However, no preconditioning method completely removes adsorption, and care should still be taken in the first 1-6 h of insulin dosing.

CONCLUSIONS

Recommendations made in this article are dependent on the insulin concentration and flow rate used in each clinical context.

Understanding and Characterizing the Drug Sorption to PVC and PE Materials

Characterizing the sorption of drugs onto polyvinylchloride (PVC) and polyethylene (PE) materials in terms of thermodynamic adsorption properties and atomistic details (local arrangements, orientation, and diffusion) is fundamental for the development of alternative materials that would limit drug sorption phenomena and plasticizer release. Here, a combination of experiments and sophisticated calculations of potential of mean forces are carried out to investigate the sorption of paracetamol and diazepam to PE and PVC surfaces. The simulated Gibbs free energies of adsorption are in line with the experimental interpretations. The polymer-drug-water interface is then characterized at the molecular scale by an in-depth investigation of local properties such as density, orientation, and diffusion.

Evaluation of regular insulin adsorption to polypropylene bag and polyvinyl chloride infusion set

AIM

Clinical application of insulin infusion therapy is usually accomplished with regular human insulin. It is known that the regular insulin adsorbed to the hydrophobic surfaces and different approaches were implemented into the clinical practices. It was aimed to evaluate the rate of adsorption of insulin to polypropylene (PP) bags and polyvinyl chloride (PVC) infusion sets and stability of insulin during the infusion.

METHODS

A 100 IU insulin was added to PP bags containing 100 mL of 0.9% NaCl solution (n = 6). The infusion was started at a rate of 2 mL/h using infusion sets in the PVC structure. Insulin quantification was performed in the samples taken both from the bag and from the end tip of the infusion set during infusion. The stability of insulin solutions stored at room (+25°C) and refrigerator (+4°C) temperatures were compared. Samples were analysed using reverse-phase high-performance liquid chromatography.

RESULTS

No statistically significant difference was found between the concentrations of the samples taken from the bags stored at room and refrigerator temperatures at the 4th, 12th, and 24th hours (P > .05). It was seen that the adsorption rate of insulin to PVC set was 57% and PP bags is at most 5% at the 24th hour.

CONCLUSION

When PP bags are used for insulin infusion, it is predicted that 24-hour change can be made instead of frequent change. In addition, losses caused by the high rate of insulin adsorption to PVC infusion sets should be considered and PP infusion sets would be the better option to use if available.

Addition of Regular Insulin to Ternary Parenteral Nutrition: A Stability Study

Background: Parenteral nutrition (PN) is a complex medium in which added insulin can become unstable. The aim of this study is, therefore, to evaluate the stability of insulin in PN and to identify influencing factors. Methods: A total of 20 IU/L of regular insulin was added to PN in either glass or Ethylene Vinyl Acetate (EVA) containers. A 24 h stability study was performed via an electrochemiluminescence immunoassay in different media: A ternary PN admixture, separate compartments of the PN bag and a binary admixture. This study was repeated in the absence of zinc, with the addition of serum albumin or tween and with pH adjustment (3.6 or 6.3). Insulin concentration at t time was expressed as a percentage of the initial insulin concentration. Analysis of covariance (ANCOVA) was applied to determine the factors that influence insulin stability. Results: In all PN admixtures, the insulin concentration ratio decreased, stabilising at a 60% and then plateauing after 6 h. At pH 3.6, the ratio was above 90%, while at pH 6.3 it decreased, except in the amino acid solution. ANCOVA (r² = 0.68, p = 0.01) identified dextrose and pH as significant factors influencing insulin stability. Conclusion: A low pH level seems to stabilise insulin in PN admixtures. The influence of dextrose content suggests that insulin glycation may influence stability.

Standardized nursing management of enzyme replacement therapy for late-onset Pompe disease

ABSTRACT

Pompe disease or glycogen storage disease type II is a rare autosomal recessive disorder caused by a deficiency of the lysosomal enzyme a-glucosidase. Although enzyme replacement therapy (ERT) with 2 weekly intervals following was considered an effective treatment for Pompe disease in 2006, few patients can afford to receive treatment in China because of the high cost. This study aimed to examine the standard management of enzyme replacement therapy for late-onset Pompe disease among patients over the age of 14 years from a nursing perspective in order to assess operating procedures. ERT injection fluid dispensing and infusion procedures using different methods were analyzed and compared in 3 patients with advanced Pompe disease for forming standard operation procedures. In addition, the impact of different methods on time consumption was analyzed by 1-way analysis of variance. There were significant differences in time consumption between different dispensing and infusion methods. The time of dispensing and infusing the injection fluids using the cooperative method was 15.97 minutes shorter than that using the conventional method (95% CI: 4.51-27.43, P = .012); the time using the modified method was 20.93 minutes shorter than that using the conventional method (95% CI: 9.47-32.39, P = .012); and there was no significant difference between the cooperative and modified methods (P = .431). Enzyme replacement therapy entails frequent treatment and strict nursing requirements related to the intravenous infusion process. In this context, a standard operating procedure can be used to control nursing times and labor costs effectively while ensuring a safe and effective infusion process.

Hyperglycaemia in the Newborn Infant. Physiology Verses Pathology

Hyperglycemia is common in newborns requiring intensive care, particularly in preterm infants, in sepsis and following perinatal hypoxia. The clinical significance, and optimal intervention strategy varies with context, but hyperglycaemia is associated with increased mortality and morbidity. The limited evidence for optimal clinical targets mean controversy remains regarding thresholds for intervention, and management strategies. The first consideration in the management of hyperglycaemia must be to ascertain potentially treatable causes. Calculation of the glucose infusion rate (GIR) to insure this is not excessive, is critical but the use of insulin is often helpful in the extremely preterm infant, but is associated with an increased risk of hypoglycaemia. The use of continuous glucose monitoring (CGM) has recently been demonstrated to be helpful in targeting glucose control, and reducing the risk from hypoglycaemia in the preterm infant. Its use in other at risk infants remains to be explored, and further studies are needed to provide a better understanding of the optimal glucose targets for different clinical conditions. In the future the combination of CGM and advances in computer algorithms, to provide intelligent closed loop systems, could allow a safer and more personalized approached to management.

Capacity of Infusion Lines for Insulin Adsorption: Effect of Flow Rate on Total Adsorption

BACKGROUND

Insulin adsorption to clinical materials has been well observed, but not well quantified. Insulin adsorption reduces expected and actual insulin delivery and is unaccounted for in insulin therapy or glycemic control. It may thus contribute to poor control and high glycemic variability. This research quantifies the problem in the context of clinical use.

METHOD

Experimental insulin adsorption data from literature is used to calculate insulin delivery and total insulin adsorption capacities for polyethylene (PE) and polyvinal chloride (PVC) lines at clinically relevant flow rates and concentrations.

RESULTS

Insulin adsorption capacity decreased hyperbolically with flow rate for both PE and PVC, where low flow scenarios result in greater insulin adherence to infusion lines. When the infusion flow rate was halved from 1 to 0.5 mL/h, twice as much insulin adsorbed to the line. Insulin loss to adsorption resulted in up to ~50% of intended insulin not delivered over 24 hours in a low flow and low concentration context.

CONCLUSION

Material capacity for insulin adsorption is not constant, but increases with decreasing flow. Different materials have different adsorption capacities. In low flow and low concentration contexts, such as in neonatal or pediatric intensive care, insulin loss to adsorption represents a significant proportion of daily insulin delivery, which needs to be accounted for.

A finite element model for insulin adsorption in ICU infusion sets

Insulin adsorption has been observed in ICU delivery lines, and is especially problematic in the delivery of insulin within the neonatal ICU. This paper presents a two state model with adsorptive loss described as a predator-prey term with parameters K_i and B_eq. This model is discretized to N sub volumes along the length of an infusion set. The model was found to converge to a solution for N>~100-150. The model was fit to literature data, and it was found that the total adsorptive capacity of a material (B_eq, U/m²) was hyperbolically related to flow rate. If the average rate constant K_i was used with the hyperbolic relationship, the model was able to describe adsorption dynamics at all 3 examined flow rates for a polyethylene line.

Impact of alternative materials to plasticized PVC infusion tubings on drug sorption and plasticizer release

Medical tubings in plasticized polyvinylchloride (PVC) are widely used for the infusion of medications but are known in some cases to cause content-container interactions (drug sorption and plasticizer release). The aim of this study was to assess interactions between drugs and five alternative materials to a reference plasticized PVC intravenous (IV) infusion tubing: three were PVC coextruded with polyethylene (PE), polyurethane (PU) or a thermoplastic elastomer (Styrene-EthyleneButadiene-Styrene (SEBS)) and two were SEBS or thermoplastic olefin (TPO) monolayer tubings. Diazepam and insulin were chosen as respective reference of absorption and adsorption while paracetamol acted as a negative control. The concentration of each drug was quantified with liquid chromatography to evaluate a potential loss after a static contact condition and simulated infusion at 1 mL/h and 10 mL/h dynamic condition by an electric syringe pump. A characterization of each material's surface was performed by Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) and by measurement of surface zeta potential. Plasticizer release was quantified by gas chromatography coupled with mass spectrometry (GC-MS). For all tubings except PVC/PU, no loss of paracetamol was observed in any condition. Diazepam sorption appeared to be less important with PVC/PE, PVC/SEBS, SEBS and TPO tubings than with PVC, but was more important when using PVC/PU tubings. PVC tubings induced the least loss of insulin amongst all the studied materials. Surface analysis by ATR-FTIR highlighted the presence of a plasticizer (that could be attributed to Tris (2-Ethylhexyl) Trimellitate (TOTM)) in the coextruded SEBS layer of PVC/SEBS, which could have influenced drug sorption, probably as a consequence of a migration from the PVC layer. Coextruded PVC/SEBS and PVC/PE presented the lowest zeta potential of all studied materials with respective values of -39 mV and -36 mV and were related to the highest sorption of insulin while PVC/PU with the highest zeta potential (about -9 mV) presented the highest absorption of diazepam. Coextruded layered materials appeared to have a lower plasticizer release than PVC alone. As a conclusion, PVC/PE and thermoplastic elastomers alone or coextruded with PVC could be interesting alternatives to PVC tubings with regards to sorption phenomena and plasticizer release.

Making Medicines Baby Size: The Challenges in Bridging the Formulation Gap in Neonatal Medicine

The development of age-appropriate formulations should focus on dosage forms that can deliver variable yet accurate doses that are safe and acceptable to the child, are matched to his/her development and ability, and avoid medication errors. However, in the past decade, the medication needs of neonates have largely been neglected. The aim of this review is to expand on what differentiates the needs of preterm and term neonates from those of the older paediatric subsets, in terms of environment of care, ability to measure and administer the dose (from the perspective of the patient and carer, the routes of administration, the device and the product), neonatal biopharmaceutics and regulatory challenges. This review offers insight into those challenges posed by the formulation of medicinal products for neonatal patients in order to support the development of clinically relevant products.

In vitro assessment of the influence of intravenous extension set materials on insulin aspart drug delivery

Insulin is a frequently prescribed drug in hospitals and is usually administered by syringe pumps with an extension line which can be made of various materials. Two insulin solutions were studied: an insulin analogue, Novorapid^® which contains insulin aspart and two phenolic preservatives (e.g. phenol and metacresol) and Umuline rapide^® with human insulin and metacresol as preservative. Some studies have indicated interactions between insulin, polyvinyl chloride (PVC) and polyethylene (PE). The aim of this work was to study such interactions between Novorapid^® or Umuline rapide^® and infusion extension line materials (PVC, PE and coextruded (PE/PVC)). Insulin solution at 1 IU/mL was infused at 2 mL/h over 24 hours with 16 different extension lines (8 in PVC, 3 in PE and 5 in PE/PVC). Ultra-Fast Liquid Chromatography with diode array detection (UFLC-DAD) was performed to quantify insulin (human and aspart) and preservatives (metacresol and phenol). Limited human insulin sorption was observed thirty minutes after the onset of infusion: 24.3 ± 12.9%, 3.1 ± 1.6% and 18.6 ± 10.0% for PVC, PE and PE/PVC respectively. With insulin aspart, sorption of about 5% was observed at the onset of infusion for all materials. However, there were interactions between phenol and especially metacresol with PVC, but no interactions with PE and PE/PVC. This study shows that insulin interacts with PVC, PE and PE/PVC at the onset of infusion. It also demonstrates that insulin preservatives interact with PVC, which may result in problems of insulin conservation and conformation. Some more studies are required to understand the clinical impact of the latter during infusion.

Insulin adsorption on functionalized silica surfaces: an accelerated molecular dynamics study

We study the influence of surface functionalization of a silica surface on insulin adsorption using accelerated molecular dynamics simulation. Three different functional groups are studied, CH₃, OH, and COOH. Due to the partial charges of these groups, the surface polarity of silica is strongly altered. We find that the adsorption energies of insulin change in agreement with the decreasing surface polarity. Conformational changes in the adsorbed protein and the magnitude of the molecular dipole moment in the adsorbed state are consistent with this result. We conclude that protein adsorption on functionalized polar surfaces is governed by the induced changes in surface polarity.

Accelerated Molecular Dynamics Study of the Effects of Surface Hydrophilicity on Protein Adsorption

The adsorption of streptavidin is studied on two surfaces, graphite and titanium dioxide, using accelerated molecular dynamics. Adsorption on graphite leads to strong conformational changes while the protein spreads out over the surface. Interestingly, also adsorption on the highly hydrophilic rutile surface induces considerable spreading of the protein. We pin down the cause for this unfolding to the interaction of the protein with the ordered water layers above the rutile surface. For special orientations, the protein penetrates the ordered water layers and comes into direct contact with the surface where the positively charged amino acids settle in places adjacent to the negatively charged top surface atom layer of rutile. We conclude that for both surface materials studied, streptavidin changes its conformation so strongly that it loses its potential for binding biotin. Our results are in good qualitative agreement with available experimental studies.

Criteria for choosing an intravenous infusion line intended for multidrug infusion in anaesthesia and intensive care units

OBJECTIVE

The aims are to identify critical parameters influencing the drug mass flow rate of infusion delivery to patients during multidrug infusion and to discuss their clinical relevance.

DATA SOURCES

A review of literature was conducted in January 2016 using Medline, Google Scholar, ScienceDirect, Web of Science and Scopus online databases.

DATA EXTRACTION

References relating to the accuracy of fluid delivery via gravity-flow intravenous (IV) infusion systems and positive displacement pumps, components of IV administration sets, causes of flow rate variability, potential complications due to flow rate variability, IV therapies especially at low flow rates and drug compatibilities were considered relevant.

DATA SYNTHESIS

Several parameters impact the delivery of drugs and fluids by IV infusion. Among them are the components of infusion systems that particularly influence the flow rate of medications and fluids being delivered. By their conception, they may generate significant start-up delays and flow rate variability. Performing multidrug infusion requires taking into account two main points: the common dead volume of drugs delivered simultaneously with potential consequences on the accuracy and amount of drug delivery and the prevention of drug incompatibilities and their clinical effects.

CONCLUSION

To prevent the potentially serious effects of flow rate variability on patients, clinicians should receive instruction on the fluid dynamics of an IV administration set and so be able to take steps to minimise flow rate changes during IV therapy.

Influence of a Double-Lumen Extension Tube on Drug Delivery: Examples of Isosorbide Dinitrate and Diazepam

Purpose

Plastic materials such as polyurethane (PUR), polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC) are widely used in double-lumen extension tubing. The purposes of our study were to 1) compare in vitro drug delivery through the double extension tubes available on the market 2) assess the plastic properties of PUR in infusion devices and their impact on drug delivery.

Methods

The study compared eight double-lumen extension tubes in PUR, co-extruded (PE/PVC) plastic and plasticised PVC from different manufacturers. Isosorbide dinitrate and diazepam were used as model compounds to evaluate their sorption on the internal surface of the infusion device. Control experiments were performed using norepinephrine known not to absorb to plastics. Drug concentrations delivered at the egress of extension tubes were determined over time by an analytical spectrophotometric UV-Vis method. The main characteristics of plastics were also determined.

Results

Significant differences in the sorption phenomenon were observed among the eight double-lumen extension tubes and between pairs of extension tubes. Mean concentrations of isosorbide dinitrate delivered at the egress of double-lumen extension tubes after a 150-minute infusion (mean values ± standard deviation in percentage of the initial concentrations in the prepared syringes) ranged between 80.53 ± 1.66 (one of the PUR tubes) and 92.84 ± 2.73 (PE/PVC tube). The same parameters measured during diazepam infusion ranged between 48.58 ± 2.88 (one of the PUR tubes) and 85.06 ± 3.94 (PE/PVC tube). The double-lumen extension tubes in PUR were either thermosetting (resin) or thermoplastic according to reference.

Conclusions

Clinicians must be aware of potential drug interactions with extension tube materials and so must consider their nature as well as the sterilisation method used before selecting an infusion device.

Development of a stable low-dose aglycosylated antibody formulation to minimize protein loss during intravenous administration

The physical and chemical integrity of a biopharmaceutical must be maintained not only during long-term storage but also during administration. Specifically for the intravenous (i.v.) delivery of a protein drug, loss of stability can occur when the protein formulation is compounded with i.v. bag diluents, thus modifying the original composition of the drug product. Here we present the challenges associated with the delivery of a low-dose, highly potent monoclonal antibody (mAb) via the i.v. route. Through parallel in-use stability studies and conventional formulation development, a drug product was developed in which adsorptive losses and critical oxidative degradation pathways were effectively controlled. This development approach enabled the i.v. administration of clinical doses in the range of 0.1 to 0.5 mg total protein, while ensuring liquid drug product storage stability under refrigerated conditions.

Intravenous drug delivery in neonates: lessons learnt

Intravenous drug administration presents a series of challenges that relate to the pathophysiology of the neonate and intravenous infusion systems in neonates. These challenges arise from slow intravenous flow rates, small drug volume, dead space volume and limitations on the flush volume in neonates. While there is a reasonable understanding of newborn pharmacokinetics, an appreciation of the substantial delay and variability in the rate of drug delivery from the intravenous line is often lacking. This can lead to difficulties in accurately determining the pharmacokinetic and pharmacodynamic relationship of drugs in the smallest patients. The physical variables that affect the passage of drugs through neonatal lines need to be further explored in order to improve our understanding of their impact on the delivery of drugs by this route in neonates. Through careful investigation, the underlying causes of delayed drug delivery may be identified and administration protocols can then be modified to ensure predictable, appropriate drug input kinetics.

Delayed delivery of intravenous gentamicin in neonates: impact of infusion variables

Objective

To investigate infusion variables that delay delivery of gentamicin through neonatal infusion lines.

Methods

Infusions were set up to simulate administration of gentamicin to neonates. The primary infusion was 10% dextrose (Baxter Colleague pump). A syringe driver was used to deliver a coloured marker via the T-connection over 35 min followed by a 1 ml normal saline flush over 35 min. Effects of dextrose concentration, primary infusion rate, dose volume and angle of the primary line were investigated. Gentamicin adsorption to in-line filters (Poisdyne Neo) and administration protocols from different neonatal intensive care units were also investigated.

Key findings

Low dose volumes (&lt;0.4 ml) infused into slow-flowing glucose (dextrose) lines (3.8–4 ml/h) did not mix well at the T-connection. Coloured solutions formed an upper layer that moved in a retrograde direction towards the primary infusion bag. Gentamicin did not adsorb onto Posidyne Neo filters. Comparison of infusion protocols for gentamicin administration showed that slow infusion (30 min) into slow-flowing lines (4 ml/h) containing 10% glucose gave low recovery of drug during the infusion (&lt;30% of intended dose).

Conclusions

Poor mixing at the T-connection appears to be the cause of delayed and/or incomplete gentamicin delivery for low dose volumes and slow infusion rates.

The effect of tubing dwell time on insulin adsorption during intravenous insulin infusions

BACKGROUND

Insulin adsorbs to plastic tubing, which decreases the concentration of an insulin solution delivered from an intravenous infusion set. Dwelling insulin within tubing before starting the infusion decreases adsorption but delays treatment initiation and wastes time in infusion preparation. The lack of data on dwell time effects results in wide variability in practice. We aim to determine the effect of dwell time on insulin concentration from intravenous infusion tubing.

MATERIALS AND METHODS

In this in vitro study, we used insulin solutions with concentrations of 0.1 unit/mL, 1 unit/mL, and 10 units/mL. Each solution dwelled in intravenous infusion sets for 0, 15, 30, or 60 min. After the dwell, we measured insulin concentrations from the solution bags and tubing. We repeated each insulin concentration-dwell time combination five times. Comparisons were performed using analyses of variance.

RESULTS

For each of the three insulin concentrations, the mean insulin concentrations from the tubing were not significantly different between dwell times. Duration of dwell time did not affect insulin adsorption in polypropylene intravenous infusion sets.

CONCLUSIONS

We recommend that following a 20-mL flush, insulin infusions can be started without any dwell time. Removal of dwell times may improve clinical practice by minimizing preparation time and will allow faster initiation of insulin infusion therapy.