Critical parameters in drug delivery by intravenous infusion

Pharmaceutical applications of therapeutic deep eutectic systems (THEDES) in maximising drug delivery

The issue of poor solubility of active pharmaceutical ingredients (APIs) has been a salient area of investigation and novel drug delivery systems are being developed to improve the solubility of drugs, enhance their permeability and thereby their efficacy. Several techniques for solubilization enhancement of poorly soluble drugs are often employed at various stages of pharmaceutical drug product development. One such delivery system is the therapeutic deep eutectic system (THEDES), which showed great potential in the enhancement of solubility and permeability of drugs and ultimately augmenting their bioavailability. THEDES are made by mixing drugs with deep eutectic solvents (DESs) in a definite molar ratio by the hit and trial method. The DESs are a new class of green solvents which are non-toxic, cheap, easy to prepare, biodegradable and have multiple applications in the pharmaceutical industry. The terminologies such as ionic liquids (ILs), DES, THEDES, and therapeutic liquid eutectic systems (THELES) have been very much in use recently, and it is important to highlight the pharmaceutical applications of these unexplored reservoirs in drug solubilization enhancement, drug delivery routes, and in the management of various diseases. This review is aimed at discussing the components, formulation strategies, and routes of administration of THEDES that are used in developing the formulation. Also, the major pharmaceutical applications of THEDES in the treatment of various metabolic and non-metabolic diseases are reviewed.

The influence of needleless connectors and inserted catheters on flow rates through vascular introducer sheaths

SummaryA vascular introducer sheath is often used for rapid volume replacement. However, common manipulations such as the addition of needleless connectors to infusion ports and the insertion of catheters or other devices through the introducer sheath may impede flow. In this study we utilised a rapid infuser to deliver room-temperature normal saline through two introducer sheath configurations with and without the addition of needleless connectors and the placement of catheters through the introducer sheaths. The maximal flow rate delivered by the rapid infuser was 1000 mL/min, which was observed with both introducer sheath sizes tested without additional resistive elements. However, with the addition of a needleless connector, flow rates through the introducer sheaths were substantially lower (64 (standard deviation (SD) 6) mL/min and 61 (SD 7) mL/min for the 8.5 Fr and 9 Fr introducers, respectively). Flow rates were also reduced when catheters were placed within the sheaths (298 (SD 9) mL/min with the 7 Fr catheter and 74 (SD 9) mL/min with the 8 Fr catheter placed in an 8.5 Fr sheath; 649 (SD 6) mL/min with the 7 Fr catheter and 356 (SD 14) mL/min with the 8 Fr catheter placed in the 9 Fr sheath). These findings indicated that both needleless connectors and the placement of catheters through vascular introducer sheaths substantially reduced potential flow rates. Even 'large' vascular introducer sheaths capable of delivering high flow rates could be rendered minimally effective for rapid fluid administration when used in this way. Clinicians should consider these impediments to flow when rapid fluid administration is required, and obtain alternative vascular access if necessary.

Effect of vertical stopcock position on start-up fluid delivery in syringe pumps used for microinfusions

The purpose of this in vitro study was to evaluate the impact of the vertical level of the stopcock connecting the infusion line to the central venous catheter on start-up fluid delivery in microinfusions. Start-up fluid delivery was measured under standardized conditions with the syringe outlet and liquid flow sensors positioned at heart level (0 cm) and exposed to a simulated CVP of 10 mmHg at a set flow rate of 1 ml/h. Flow and intraluminal pressures were measured with the infusion line connected to the stopcock primarily placed at vertical levels of 0 cm, + 30 cm and - 30 cm or primarily placed at 0 cm and secondarily, after connecting the infusion line, displaced to + 30 cm and - 30 cm. Start-up fluid delivery 10 s after opening the stopcock placed at zero level and after opening the stopcock primarily connected at zero level and secondary displaced to vertical levels of + 30 cm and - 30 cm were similar (- 10.52 [- 13.85 to - 7.19] µL; - 8.84 [- 12.34 to - 5.33] µL and - 11.19 [- 13.71 to - 8.67] µL (p = 0.469)). Fluid delivered at 360 s related to 65% (zero level), 71% (+ 30 cm) and 67% (- 30 cm) of calculated infusion volume (p = 0.395). Start-up fluid delivery with the stopcock primarily placed at + 30 cm and - 30 cm resulted in large anterograde and retrograde fluid volumes of 34.39 [33.43 to 35.34] µL and - 24.90 [- 27.79 to - 22.01] µL at 10 s, respectively (p < 0.0001). Fluid delivered with the stopcock primarily placed at + 30 cm and - 30 cm resulted in 140% and 35% of calculated volume at 360 s, respectively (p < 0.0001). Syringe infusion pumps should ideally be connected to the stopcock positioned at heart level in order to minimize the amounts of anterograde and retrograde fluid volumes after opening of the stopcock.

Evaluation of the venting principle to reduce start-up delays in syringe infusion pumps used for microinfusions

Start-up delays of syringe pump assemblies can impede the timely commencement of an effective drug therapy when using microinfusions in hemodynamically unstable patients. The application of the venting principle has been proposed to eliminate start-up delays in syringe pump assemblies. However, effectively delivered infusion volumes using this strategy have so far not been measured. This invitro study used two experimental setups to measure the effect of the venting principle compared to a standard non-venting approach on delivered start-up infusion volumes at various timepoints, backflow volumes, flow inversion and zero drug delivery times by means of liquid flow measurements at flow rates of 0.5, 1.0 and 2.0 mL/h. Measured delivered initial start-up volumes were negative with all flow rates in the vented and non-vented setup. Maximum backflow volumes were 1.8 [95% CI 1.6 to 2.3] times larger in the vented setup compared to the non-vented setup (p < 0.0001). Conversely, times until flow inversion were 1.5 [95% CI 1.1 to 2.9] times shorter in the vented setup (p < 0.002). This led to comparable zero drug delivery times between the two setups (p = 0.294). Start-up times as defined by the achievement of at least 90% of steady state flow rate were achieved faster with the vented setup (p < 0.0001), but this was counteracted by the increased backflow volumes. The application of the venting principle to the start-up of microinfusions does not improve the timely delivery of drugs to the patient since the faster start-up times are counteracted by higher backflow volumes when opening the three-way stopcock.

A self-powered spiral droplet triboelectric sensor for real-time monitoring of patient infusion in nursing wards

Monitoring of intravenous infusion together with an alarm system is significant for safety and automation operation in the process of clinical drug delivery for major medical institutions. However, there is still a lack of multifunctional sensors to monitor the whole infusion process, such as flow rate, drip rate, and temperature. Herein, we propose a self-powered droplet triboelectric sensor (SDTS) based on the principle of liquid-solid triboelectrification to monitor both intravenous infusion flow and infusion type. Such SDTS devices use two materials with different electrically charged properties to directly generate an electrical signal without any additional power supply, which is conducive to the formation of a large-scale detection system and for enhancing the convenience of medical treatment. The SDTS placed in a disposable infusion set has high potential application in clinical practice and is low cost and easy to prepare. Specifically, we demonstrate the feasibility of the detection of the current infusion flow rate and identification of the infusion medicine type according to the triboelectric signals, providing a new solution for real-time monitoring of patient infusion in nursing wards.

Effect of vertical pump position on start-up fluid delivery of syringe pumps used for microinfusion

BACKGROUND

Connection and opening a syringe infusion pump to a central venous line can lead to acute anterograde or retrograde fluid shifts depending on the level of central venous pressure. This may lead to bolus events or to prolonged lag times of intravenous drug delivery, being particularly relevant when administering vasoactive or inotropic drugs in critically ill patients using microinfusion. The aim of this study was to assess the effect of syringe pump positioning at different vertical heights on start-up fluid delivery before versus after purging and connection the pump to the central venous catheter.

METHODS

This in vitro study measured ante- and retrograde infusion volumes delivered to the central venous line after starting the syringe pump at a set infusion rate of 1 mL/h. In setup one, the pump was first positioned to vertical levels of +43 cm or -43 cm and then purged and connected to a central venous catheter. In setup two, the pump was first purged and connected at zero level and secondarily positioned to a vertical level of +43 cm or -43 cm. Central venous pressure was adjusted to 10 mmHg in both setups.

RESULTS

Positioning of the pump prior to purging and connection to the central venous catheter resulted in a better start-up performance with delivered fluid closer to programmed and expected infusion volumes when compared to the pump first purged, connected, and then positioned. Significant backflow volumes were observed with the pump purged and connected first and then positioned below zero level. No backflow was measured with the pump positioned first below zero level and then purged and connected.

CONCLUSIONS

Syringe infusion pump assemblies should be positioned prior to purging and connection to a central venous catheter line when starting a new drug, particularly when administering highly concentrated vasoactive or inotropic drugs delivered at low flow rates.

Current advances of nanocellulose application in biomedical field

Nanocellulose (NC) is a natural fiber that can be extracted in fibrils or crystals form from different natural sources, including plants, bacteria, and algae. In recent years, nanocellulose has emerged as a sustainable biomaterial for various medicinal applications including drug delivery systems, wound healing, tissue engineering, and antimicrobial treatment due to its biocompatibility, low cytotoxicity, and exceptional water holding capacity for cell immobilization. Many antimicrobial products can be produced due to the chemical functionality of nanocellulose, such disposable antibacterial smart masks for healthcare use. This article discusses comprehensively three types of nanocellulose: cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and bacterial nanocellulose (BNC) in view of their structural and functional properties, extraction methods, and the distinctive biomedical applications based on the recently published work. On top of that, the biosafety profile and the future perspectives of nanocellulose-based biomaterials have been further discussed in this review.

Precision and reliability study of hospital infusion pumps: a systematic review

BACKGROUND

Infusion Pumps (IP) are medical devices that were developed in the 1960s and generate fluid flow at pressures higher than that of normal blood pressure. Various hospital sectors make use of them, and they have become indispensable in therapies requiring continuity and precision in the administration of medication and/or food. As they are classified Class III (high risk) equipment, their maintenance is crucial for proper performance of the device, as well as patient and operator safety. The principal consideration of the pump is the volume infused, and the device demands great attention to detail when being calibrated. A lack of necessary care with this equipment can lead to uncertainty in volume and precision during the administration of substances. Because of this, it is essential to evaluate its reliability, to prevent possible failures at time of execution. This control aims at the quality of the intended infusion result, becoming an indication of quality.

METHODS

This systematic review summarizes studies done over the last 10 years (2011 to December 2021) that address the reliability and accuracy of hospital infusion pumps, in order to identify planning of maintenance and/or other techniques used in management of the equipment. The Prisma method was applied and the databases utilized were Embase, MEDLINE/Pubmed, Web of Science, Scopus, IEEE Xplore, and Science Direct. In addition, similar reviews were studied in Prospero and the Cochrane Library. For data analysis, softwares such as Mendeley, Excel, RStudio, and VOSviewer were used, and Robvis helped in plotting risk of bias results for studies performed with Cochrane tools.

RESULTS

The six databases selected produced 824 studies. After applying eligibility criteria (inclusion and exclusion), removing duplicates, and applying filters 1 and 2, 15 studies were included in the present review. It was found that the most relevant sources came from the Institute of Electrical and Electronics Engineers (IEEE) and that the most relevant keywords revolved around the terms ("device failure", "infusion pumps", "adverse effects", "complications", etc.). These results made clear that there remains substantial room for improvement as it relates to the study of accuracy and reliability of infusion.

CONCLUSIONS

We verified that the reliability and precision analysis of hospital infusion pumps need to be performed in a more detailed and consistent way. New developments, considering the model and IP specification, are intended, clearly explaining the adopted methodology.

Simultaneous infusion of two incompatible antibiotics: Impact of the choice of infusion device and concomitant simulated fluid volume support on the particulate load and the drug mass flow rates

Vancomycin and piperacillin/tazobactam are known to be incompatible. The objectives of the present study were to evaluate the impact of their simultaneous infusion on mass flow rates and particulate load and identify preventive strategies. We assessed both static conditions and a reproduction of an infusion line used in a hospital's critical care unit. A high-performance liquid chromatography/UV diode array system and static and dynamic laser diffraction particle counters were used. The mass flow rates were primarily influenced by the choice of the infusion device and the presence of simulated fluid volume support. Drug incompatibility also appeared to affect vancomycin's mass flow rate, and the dynamic particulate load increased during flow rate changes - especially in the infusion set with a large common volume line and no concomitant simulated fluid volume support. Only discontinuation of the piperacillin/tazobactam infusion was associated with a higher particulate load in the infusion set with a large common volume line and no concomitant simulated fluid volume support. A low common volume line and the use of simulated fluid volume support were associated with smaller fluctuations in the mass flow rate. The clinical risk associated with a higher particulate load must now be assessed.

Development of a Population Pharmacokinetic Model of Busulfan in Children and Evaluation of Different Sampling Schedules for Precision Dosing

We develop a population pharmacokinetic model to describe Busulfan pharmacokinetics in paediatric patients and investigate by simulations the impact of various sampling schedules on the calculation of AUC. Seventy-six children had 2 h infusions every 6 h. A two-compartment linear model was found to adequately describe the data. A lag-time was introduced to account for the delay of the administration of the drug through the infusion pump. The mean values of clearance, central volume of distribution, intercompartmental clearance, and peripheral volume of distribution were 10.7 L/h, 39.5 L, 4.68 L/h and 17.5 L, respectively, normalized for a Body Weight (BW) of 70 kg. BW was found to explain a portion of variability with an allometric relationship and fixed exponents of 0.75 on clearance parameters and 1 on volumes. Interindividual variability for clearance and volume of distribution was found to be 28% and 41%, respectively, and interoccasion variability for clearance was found to be 11%. Three sampling schedules were assessed by simulations for bias and imprecision to calculate AUC by a non-compartmental and a model-based method. The latter was found to be superior in all cases, while the non-compartmental was unbiased only in sampling up to 12 h corresponding to a once-daily dosing regimen.

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.

An updated review on application of 3D printing in fabricating pharmaceutical dosage forms

The concept of "one size fits all" followed by the conventional healthcare system has drawbacks in providing precise pharmacotherapy due to variation in the pharmacokinetics of different patients leading to serious consequences such as side effects. In this regard, digital-based three-dimensional printing (3DP), which refers to fabricating 3D printed pharmaceutical dosage forms with variable geometry in a layer-by-layer fashion, has become one of the most powerful and innovative tools in fabricating "personalized medicine" to cater to the need of therapeutic benefits for patients to the maximum extent. This is achieved due to the tremendous potential of 3DP in tailoring various drug delivery systems (DDS) in terms of size, shape, drug loading, and drug release. In addition, 3DP has a huge impact on special populations including pediatrics, geriatrics, and pregnant women with unique or frequently changing medical needs. The areas covered in the present article are as follows: (i) the difference between traditional and 3DP manufacturing tool, (ii) the basic processing steps involved in 3DP, (iii) common 3DP methods with their pros and cons, (iv) various DDS fabricated by 3DP till date with discussing few research studies in each class of DDS, (v) the drug loading principles into 3D printed dosage forms, and (vi) regulatory compliance.

Digital droplet infusion

Infusion pumps have been widely used in clinical settings for the administration of medications and fluids. We present the digital droplet infusion (DDI) device, a low-cost, high-precision digital infusion system, utilizing a microfluidic discretization unit to convert continuous flow into precisely delivered droplet aliquots and a valving unit to control the duration and frequency of flow discretization. The DDI device relies on a distinct capillarity-dominated process of coalescence and pinch-off of droplets for flow digitization, which is monitored by a pair of conductive electrodes located before and after the junction. The digital feedback-controlled flow rate can be employed to adjust a solenoid valve for refined infusion management. With this unique digital microfluidic approach, the DDI technology enables a simple yet powerful infusion system with an ultrahigh resolution of digital droplet transfer volume, as small as 57 nL, which is three orders of magnitude lower than that of clinical standard infusion pumps, as well as a wide range of digitally adjustable infusion rates ranging from 0.1 mL h^-1 to 10 mL h^-1, in addition to an array of programmable infusion profiles and safety features. Its modular design enables fast assembly using only off-the-shelf and 3D-printed components. Overall, benefiting from its simple device architecture and excellent infusion performance, the DDI technology has great potential to become the next-generation clinical standard for drug delivery with its high precision and ultimate portability at a low cost.

Nanocellulose in Drug Delivery and Antimicrobially Active Materials

In recent years, nanocellulose (NC) has also attracted a great deal of attention in drug delivery systems due to its unique physical properties, specific surface area, low risk of cytotoxicity, and excellent biological properties. This review is focused on nanocellulose based systems acting as carriers to be used in drug or antimicrobial delivery by providing different but controlled and sustained release of drugs or antimicrobial agents, respectively, thus showing potential for different routes of applications and administration. Microorganisms are increasingly resistant to antibiotics, and because, generally, the used metal or metal oxide nanoparticles at some concentration have toxic effects, more research has focused on finding biocompatible antimicrobial agents that have been obtained from natural sources. Our review contains the latest research from the last five years that tested nanocellulose-based materials in the field of drug delivery and antimicrobial activity.

Quantitative assessment of required separator fluid volume in multi-infusion settings

BACKGROUND

Administering a separator fluid between incompatible solutions can optimize the use of intravenous lumens. Factors affecting the required separator fluid volume to safely separate incompatible solutions are unknown.

METHODS

An intravenous tube (2-m, 2-mL, 6-French) containing methylene blue dye was flushed with separator fluid until a methylene blue concentration ⩽2% from initial was reached. Independent variables were administration rate, dye solvent (glucose 5% and NaCl 0.9%), and separator fluid. In the second part of the study, methylene blue, separator fluid, and eosin yellow were administered in various administration profiles using 2- and 4-mL (2 × 2 m, 4-mL, 6-French) intravenous tubes.

RESULTS

Neither administration rate nor solvent affected the separator fluid volume (p = 0.24 and p = 0.12, respectively). Glucose 5% as separator fluid required a marginally smaller mean ± SD separator fluid volume than NaCl 0.9% (3.64 ± 0.13 mL vs 3.82 ± 0.11 mL, p < 0.001). Using 2-mL tubing required less separator fluid volume than 4-mL tubing for methylene blue (3.89 ± 0.57 mL vs 4.91 ± 0.88 mL, p = 0.01) and eosin yellow (4.41 ± 0.56 mL vs 5.63 ± 0.15 mL, p < 0.001). Extended tubing required less separator fluid volume/mL of tubing than smaller tubing for both methylene blue (2 vs 4 mL, 1.54 ± 0.22 vs 1.10 ± 0.19, p < 0.001) and eosin yellow (2 vs 4 mL, 1.75 ± 0.22 vs 1.25 ± 0.03, p < 0.001).

CONCLUSION

The separator fluid volume was neither affected by the administration rate nor by solvent. Glucose 5% required a marginally smaller separator fluid volume than NaCl 0.9%, however its clinical impact is debatable. A larger intravenous tubing volume requires a larger separator fluid volume. However, the ratio of separator fluid volume to the tubing's volume decreases as the tubing volume increases.

Papain-Like Proteases as Coronaviral Drug Targets: Current Inhibitors, Opportunities, and Limitations

Papain-like proteases (PLpro) of coronaviruses (CoVs) support viral reproduction and suppress the immune response of the host, which makes CoV PLpro perspective pharmaceutical targets. Their inhibition could both prevent viral replication and boost the immune system of the host, leading to the speedy recovery of the patient. Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the third CoV outbreak in the last 20 years. Frequent mutations of the viral genome likely lead to the emergence of more CoVs. Inhibitors for CoV PLpro can be broad-spectrum and can diminish present and prevent future CoV outbreaks as PLpro from different CoVs have conservative structures. Several inhibitors have been developed to withstand SARS-CoV and Middle East respiratory syndrome CoV (MERS-CoV). This review summarizes the structural features of CoV PLpro, the inhibitors that have been identified over the last 20 years, and the compounds that have the potential to become novel effective therapeutics against CoVs in the near future.

Does carrier fluid reduce low flow drug infusion error from syringe size?

BACKGROUND

Critically ill neonates and pediatric patients commonly require multiple low flow infusions. Volume limitations are imposed by small body habitus and co-morbidities like cardiopulmonary disease, renal failure, or fluid overload. Vascular access is limited by diminutive veins. Maintenance fluids or parenteral nutrition in conjunction with actively titrated infusions such as insulin, fentanyl, prostaglandins, inotropes and vasopressors may necessitate simultaneous infusions using a single lumen to maintain vascular catheter patency. This requirement for multiple titratable infusions requires concentrated medications at low flows, rather than more dilute drugs at higher flows that in combination may volume overload small infants.

AIM

To determine whether carrier fluid reduces variability that variability of low flow drug infusions is proportional to syringe size in pediatric critical care.

METHODS

We assessed concentrations of orange “drug” in a 0.2 mL/h low flow clinical model with blue dyed carrier fluid at 5 mL/h, using 3-, 10-, or 60-mL syringes. A graduated volumetric pipette was used to measure total flow. Mean time to target concentration was 30, 21, and 46 min in 3-, 10-, and 60-mL syringes, respectively (P = 0.42). After achieving target concentration, more dilute drug was delivered by 60-mL (P < 0.001) and 10-mL syringes (P = 0.04) compared to 3-mL syringes. Drug overdoses were observed during the initial 45 min of infusion in 10-and 60-mL syringes. Total volumes infused after target concentration were less in the 60-mL condition compared to 3-mL (P < 0.01) and 10-mL (P < 0.001) syringes.

RESULTS

Linear mixed effects models demonstrated lesser delivered drug concentrations in the initial 30 min by 3-mL compared to 10-and 60-mL syringes (P = 0.005 and P < 0.001, respectively) but greater drug concentrations and total infused drug in the subsequent 30-60 and 60-90 min intervals with the 3- and 10-mL compared to 60-mL syringes.

CONCLUSION

With carrier fluid, larger syringes were associated with significantly less drug delivery, less total volume delivered, and other flow problems in our low flow drug model. Carrier fluid should not be used to compensate for inappropriately large syringes in critical low flow drug infusions.

Additive Manufacturing Technologies for Drug Delivery Applications

Patient to patient variability is one of the issues when administering medications to individuals with different health conditions, pharmacokinetic, age, fitness, gender, and race. This requires introducing smart and personalised drug delivery systems with controlled release profile manufactured using novel approaches. Additive manufacturing (AM) provides opportunities such as full customisation, design freedom, and on-site manufacturing, and materials recycling. As a result, the academic and industrial demand for additive manufacturing for drug delivery has been continuously increasing and showing impressive results for a wide range of products. This paper provides an extensive overview of AM technologies and their applications for drug delivery. The review discusses AM technologies including their working principles, processed materials, as well as current progress in drug delivery to produce personalized dosages for every patient with controlled release profile. AM potentials, industrial scale, and challenges are investigated with regards to practice and industrial applications. The paper covers novel possibilities of AM technologies and their pharmaceuticals applications, which indicate a promising healthcare future.

Digital microfluidic meter-on-chip

The accurate monitoring and control of liquid flow at low flow rates have become increasingly important in contemporary biomedical research and industrial monitoring. Inspired by the drop-counting principle implemented in a clinical gravity drip, we propose a novel microfluidic flowmetry technology for polydimethylsiloxane (PDMS)-based conventional microfluidic devices, known as a microfluidic digital meter-on-chip (DMC), to achieve on-chip and localized microflow measurements with ultrahigh precision and a wide tunable range. The DMC technology primarily relies on capillarity, unlike a gravity drip, to induce a characteristic interfacial droplet pinch-off process, from which digital microflowmetry devices can discretize continuous flow into countable transferred liquid units with consistent quantifiable volumes. Enabled by the passive discretization principle and optical transparency, the DMC device requires no external energy input or bulky control equipment, and a non-contact wireless optical detection scheme using a smartphone can be conveniently used as a readout module. Moreover, the DMC technology achieves an ultrahigh flow-to-frequency sensitivity (6.59 Hz (μL min^-1)^-1) and resolution (droplet transfer volume down to 2.5 nL, nearly two orders of magnitude smaller than in previously reported work, resulting in ultralow flow rates of 1 μL min^-1). In addition, the flow rate measurement range covers up to 80 μL min^-1 and down to at least 150 nL min^-1 (over 100 times lower than reported similar digital flowmetry on the same time scale) using the current device configuration. Benefiting from its simple device architecture and adaptability, the versatile DMC technology can be seamlessly integrated with various microfluidic and nanofluidic devices for drug delivery and biochemical analysis, serving as a promising technology platform for next-generation highly demanding microflow measurements.

Best Practice for Delivering Small-Volume Intermittent Intravenous Infusions

This study investigated the delivery of small-volume intermittent intravenous (IV) infusions. Laboratory protocol evaluated potential medication loss among 6 administration methods using 50- and 100-mL solutions. Significant variations existed in calculated medication loss depending on administration method and volume. Up to 35% of medication may not be administered due to residual volume, with the greatest percentage associated with 50-mL solutions. Results suggest that intermittent IV infusions should only be delivered as a secondary infusion through a primary infusion administration set with a continuous infusion or an infusion that can flush the administration set at the completion of the secondary infusion.

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.

Impact of Physical Parameters on Dosing Errors due to a Syringe Exchange in Multi-Infusion Therapy

Introduction

Infusion therapy is challenging and dosing errors may occur due to physical phenomena related to the infusion hardware, despite the use of accurate syringe pumps. These errors typically occur after interventions, such as the exchange of a syringe. We aimed to characterize and quantify dosing errors due to a syringe exchange in relation to physical properties of infusion hardware.

Methods

An analytical simulation model was used to investigate dosing errors due to two different syringe exchange protocols (variations). Each protocol involved a fast syringe pump, containing a non-critical medication, and a slow syringe pump, containing a critical drug. The protocols were also reproduced in

Results

The syringe exchange of the slow pump resulted in an additional delay of up to 3536 seconds due to backflow. Syringe exchange of the fast pump resulted in an undiluted volume of critical drug (0.17 ml) accumulated in the infusion system, which may result in a dosing error rate of 2400 %. The quantity of the dosing errors are related to the syringe exchange duration; however, impact of infusion hardware properties is generally larger. Smaller syringes, catheters with larger diameters and less compliant infusion systems in general give rise to smaller dosing errors during a syringe exchange. If both lines are clamped, additional dosing errors can be prevented.

Conclusion

Infusion hardware has a substantial impact on the dosing errors during a syringe exchange. Clamping or blocking the infusion lines using, e. g. stopcocks, on all infusion lines during a syringe exchange is essential.

Drug Infusion Systems: Technologies, Performance, and Pitfalls

This review aims to broadly describe drug infusion technologies and raise subtle but important issues arising from infusion therapy that can potentially lead to patient instability and morbidity. Advantages and disadvantages of gravity-dependent drug infusion are described and compared with electromechanical approaches for precise control of medication infusion, including large-volume peristaltic and syringe pumps. This review discusses how drugs and inert carriers interact within infusion systems and outlines several complexities and potential sources of drug error. Major topics are (1) the importance of the infusion system dead volume; (2) the quantities of coadministered fluid and the concept of microinfusion; and (3) future directions for drug infusion.The infusion system dead volume resides between the point where drug and inert carrier streams meet and the patient's blood. The dead volume is an often forgotten reservoir of drugs, especially when infusion flows slow or stop. Even with medications and carriers flowing, some mass of drug always resides within the dead volume. This reservoir of drug can be accidentally delivered into patients. When dose rate is changed, there can be a significant lag between intended and actual drug delivery. When a drug infusion is discontinued, drug delivery continues until the dead volume is fully cleared of residual drug by the carrier. When multiple drug infusions flow together, a change in any drug flow rate transiently affects the rate of delivery of all the others. For all of these reasons, the use of drug infusion systems with smaller dead volumes may be advantageous.For critically ill patients requiring multiple infusions, the obligate amount of administered fluid can contribute to volume overload. Recognition of the risk of overload has given rise to microinfusion strategies wherein drug solutions are highly concentrated and infused at low rates. However, potential risks associated with the dead volume may be magnified with microinfusion. All of these potential sources for adverse events relating to the infusion system dead volume illustrate the need for continuing education of clinical personnel in the complexities of drug delivery by infusion.This review concludes with an outline of future technologies for managing drug delivery by continuous infusion. Automated systems based on physiologic signals and smart systems based on physical principles and an understanding of dead volume may mitigate against adverse patient events and clinical errors in the complex process of drug delivery by infusion.

Analytical method for calculation of deviations from intended dosages during multi-infusion

BACKGROUND

In this paper, a new method is presented that combines mechanical compliance effects with Poiseuille flow and push-out effects ("dead volume") in one single mathematical framework for calculating dosing errors in multi-infusion set-ups. In contrast to existing numerical methods, our method produces explicit expressions that illustrate the mathematical dependencies of the dosing errors on hardware parameters and pump flow rate settings.

METHODS

Our new approach uses the Z-transform to model the contents of the catheter, and after implementation in Mathematica (Wolfram), explicit expressions are produced automatically. Consistency of the resulting analytical expressions has been examined for limiting cases, and three types of in-vitro measurements have been performed to obtain a first experimental test of the validity of the theoretical results.

RESULTS

The relative contribution of various factors affecting the dosing errors, such as the Poiseuille flow profile, resistance and internal volume of the catheter, mechanical compliance of the syringes and the various pump flow rate settings, can now be discerned clearly in the structure of the expressions generated by our method. The in-vitro experiments showed a standard deviation between theory and experiment of 14% for the delay time in the catheter, and of 13% for the time duration of the dosing error bolus.

CONCLUSIONS

Our method provides insight and predictability in a large range of possible situations involving many variables and dependencies, which is potentially very useful for e.g. the development of a fast, bed-side tool ("calculator") that provides the clinician with a precise prediction of dosing errors and delay times interactively for many scenario's. The interactive nature of such a device has now been made feasible by the fact that, using our method, explicit expressions are available for these situations, as opposed to conventional time-consuming numerical simulations.

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.

Automatic versus manual changeovers of norepinephrine infusion pumps in critically ill adults: a prospective controlled study

Background

Norepinephrine is a key drug for treating shock but has a short half-life that requires continuous intravenous administration to maintain the constant plasma concentration needed to obtain a stable blood pressure. The small volume of the syringes used in power infusion pumps requires frequent changeovers, which can lead to norepinephrine flow interruptions responsible for hemodynamic instability. Changeovers from the nearly empty to the full syringe can be performed manually using the quick change technique (QC) or automatically using smart infusion pumps (SIP) that link two syringes. The purpose of our study was to evaluate the hypothesis that, compared to QC, SIP for norepinephrine changeovers was associated with less hemodynamic instability.

Methods

After information of the patient or next of kin, patients receiving norepinephrine for shock were allocated to QC or SIP changeovers. QC changeovers were performed by a nurse, who started a new loaded pump when the previous syringe was nearly empty. SIP changeovers were managed automatically by SIP workstations. The primary outcome was the proportion of changeovers followed by a ≥20 % drop in mean arterial pressure (MAP).

Results

411 changeovers were performed, 193 in the 18 patients allocated to QC and 218 in the 32 patients allocated to SIP. Baseline patient characteristics were similar in both groups. The proportion of changeovers followed by an MAP drop ≥20 % was 12.4 % (24/193) with QC and 5.5 % (12/218) with SIP (P = 0.01). By multivariate analysis, two factors were independently associated with a significantly decreased risk of ≥20 % MAP drops during changeovers, namely, SIP (odds ratio, 0.47; 95 % confidence interval, 0.22–0.98) and norepinephrine dosage >0.5 μg/kg/min (odds ratio, 0.39; 95 % confidence interval, 0.19–0.81).

Conclusions

The risk of MAP drops ≥20 % during changeovers can be significantly diminished using SIPs instead of the QC method.

Trial registration: Clinicaltrial.gov NCT 01127152

Computer control of drug delivery by continuous intravenous infusion: bridging the gap between intended and actual drug delivery

BACKGROUND

Intravenous drug infusion driven by syringe pumps may lead to substantial temporal lags in achieving steady-state delivery at target levels when using very low flow rates ("microinfusion"). This study evaluated computer algorithms for reducing temporal lags via coordinated control of drug and carrier flows.

METHODS

Novel computer control algorithms were developed based on mathematical models of fluid flow. Algorithm 1 controlled initiation of drug infusion and algorithm 2 controlled changes to ongoing steady-state infusions. These algorithms were tested in vitro and in vivo using typical high and low dead volume infusion system architectures. One syringe pump infused a carrier fluid and a second infused drug. Drug and carrier flowed together via a manifold through standard central venous catheters. Samples were collected in vitro for quantitative delivery analysis. Parameters including left ventricular max dP/dt were recorded in vivo.

RESULTS

Regulation by algorithm 1 reduced delivery delay in vitro during infusion initiation by 69% (low dead volume) and 78% (high dead volume). Algorithmic control in vivo measuring % change in max dP/dt showed similar results (55% for low dead volume and 64% for high dead volume). Algorithm 2 yielded greater precision in matching the magnitude and timing of intended changes in vivo and in vitro.

CONCLUSIONS

Compared with conventional methods, algorithm-based computer control of carrier and drug flows can improve drug delivery by pump-driven intravenous infusion to better match intent. For norepinephrine infusions, the amount of drug reaching the bloodstream per time appears to be a dominant factor in the hemodynamic response to infusion.

Synthesis and in vitro evaluation of amphiphilic peptides and their nanostructured conjugates

PURPOSE

Breast cancer is the second leading cancer type among people of advanced countries. Various methods have been used for cancer treatment such as chemotherapy and radiotherapy. In the present study we have designed and synthesized a new group of drug delivery systems (DDS) containing a new class of Cell Penetrating Peptides (CPPs) named Peptide Amphiphiles (PAs).

METHODS

Two PAs and anionic peptides were synthesized using solid phase peptide synthesis (SPPS), namely [KW]4, [KW]5, E4 and E8. Then nano-peptides were synthesized by non-covalent binding between PAs and poly anions as [KW]4-E4, [KW]4-E8, [KW]5-E4 and [KW]5-E8.

RESULTS

Flow cytometry studies showed that increased chain length of PAs with a higher ratio between hydrophobicity and net charge results in increased intracellular uptake by MCF7 cells after 2h incubation. Moreover, nano-peptides showed greater intracellular uptake compared to PAs. Anti-proliferative assay revealed that by increasing chain length of PAs, the toxicity effect on MCF7 cells is reduced, however nano-peptides did not show significant toxicity on MCF7 cells even at high concentration levels.

CONCLUSION

These data suggest that due to the lack of toxicity effect at high concentration levels and also high cellular uptake, nano-peptides are more suitable carrier compared to PAs for drug delivery.

Sources of preanalytical error in pharmacokinetic analyses - focus on intravenous drug administration and collection of blood samples

INTRODUCTION

Pharmacokinetic (PK) studies for long-established drugs are generally performed outside the well-standardized settings of pharmaceutical industry trials. Instead, such studies are usually performed within daily clinical practice of hospitals.

AREAS COVERED

This article describes aspects of intravenous (i.v.) drug administration and blood sampling that contribute to potential sources of preanalytical errors for PK investigations. Parameters that bias determination of start and end time of i.v. infusions, as well as consistent rate of drug delivery, are discussed. Causes for drug loss in the infusion device, including adsorption and insufficient flushing, are outlined. The advantages and disadvantages of different blood sampling techniques are reviewed, with an emphasis on pediatric studies.

EXPERT OPINION

For PK studies that are integrated into the general hospital routine, a variety of potential sources of error exist. Potential pitfalls depend on the specific drug and trial characteristics and they must be anticipated and discussed in advance. Working procedures need to be developed that address the anticipated problems and in detail describe procedures that need compliance between bed and bench.

Peptide amphiphile containing arginine and fatty acyl chains as molecular transporters

Peptide amphiphiles (PAs) are promising tools for the intracellular delivery of numerous drugs. PAs are known to be biodegradable systems. Here, four PA derivatives containing arginine and lysine conjugated with fatty acyl groups with different chain lengths, namely, PA1: R-K(C14)-R, PA2: R-K(C16)-R, PA3: K(C14)-R-K(C14), and PA4: K(C16)-R-K(C16), where C16 = palmitic acid and C14 = myristic acid, were synthesized through Fmoc chemistry. Flow cytometry studies showed that, among all synthesized PAs, only K(C16)-R-K(C16), PA4 was able to enhance the cellular uptake of a fluorescence-labeled anti-HIV drug 2',3'-dideoxy-3'-thiacythidine (F'-3TC, F' = fluorescein) and a biologically important phosphopeptide (F'-PEpYLGLD) in human leukemia cells (CCRF-CEM) after 2 h incubation. For example, the cellular uptake of F'-3TC and F'-PEpYLGLD was enhanced approximately 7.1- and 12.6-fold in the presence of the PA4 compared to those of the drugs alone. Confocal microscopy of F'-3TC and F'-PEpYLGLD loaded PA4 in live cells showed significantly higher intracellular localization than the drug alone in human ovarian cells (SK-OV-3) after 2 h incubation. The high-performance liquid chromatography (HPLC) results showed that loading of Dox by the peptide amphiphile was 56% after 24 h. The loaded Dox was released (34%) within 48 h intracellularly. The circular dichrosim (CD) results exhibited that the secondary structure of the peptide was changed upon interactions with Dox. Mechanistic studies revealed that endocytosis is the major pathway of the internalization. These studies suggest that PAs containing the appropriate sequence of amino acids, chain length, charge, and hydrophobicity can be used as cellular delivery tools for transporting drugs and biomolecules.