A Degron Blocking Strategy Towards Improved CRL4CRBN Recruiting PROTAC Selectivity.

Small molecules inducing protein degradation are important pharmacological tools to interrogate complex biology and are rapidly translating into clinical agents. However, to fully realise the potential of these molecules, selectivity remains a limiting challenge. Herein, we addressed the issue of selectivity in the design of CRL4CRBN recruiting PROteolysis TArgeting Chimeras (PROTACs). Thalidomide derivatives used to generate CRL4CRBN recruiting PROTACs have well described intrinsic monovalent degradation profiles by inducing the recruitment of neo-substrates, such as GSPT1, Ikaros and Aiolos. We leveraged structural insights from known CRL4CRBN neo-substrates to attenuate and indeed remove this monovalent degradation function in well-known CRL4CRBN molecular glues degraders, namely CC-885 and Pomalidomide. We then applied these design principles on a previously published BRD9 PROTAC (dBRD9-A) and generated an analogue with improved selectivity profile. Finally, we implemented a computational modelling pipeline to show that our degron blocking design does not impact PROTAC-induced ternary complex formation. We believe that the tools and principles presented in this work will be valuable to support the development of targeted protein degradation.

Investigating the phosphinic acid tripeptide mimetic DG013A as a tool compound inhibitor of the M1-aminopeptidase ERAP1.

ERAP1 is a zinc-dependent M1-aminopeptidase that trims lipophilic amino acids from the N-terminus of peptides. Owing to its importance in the processing of antigens and regulation of the adaptive immune response, dysregulation of the highly polymorphic ERAP1 has been implicated in autoimmune disease and cancer. To test this hypothesis and establish the role of ERAP1 in these disease areas, high affinity, cell permeable and selective chemical probes are essential. DG013A 1, is a phosphinic acid tripeptide mimetic inhibitor with reported low nanomolar affinity for ERAP1. However, this chemotype is a privileged structure for binding to various metal-dependent peptidases and contains a highly charged phosphinic acid moiety, so it was unclear whether it would display the high selectivity and passive permeability required for a chemical probe. Therefore, we designed a new stereoselective route to synthesize a library of DG013A 1 analogues to determine the suitability of this compound as a cellular chemical probe to validate ERAP1 as a drug discovery target.

Usability evaluation of an integrated electronic medication management system implemented in an oncology setting using the unified theory of the acceptance and use of technology.

BACKGROUND: Medication management processes in an Oncology setting are complex and difficult to examine in isolation from interrelated processes and contextual factors. This qualitative study aims to evaluate the usability of an Electronic Medication Management System (EMMS) implemented in a specialised oncology unit using the Unified Theory of Acceptance and Use of Technology (UTAUT) framework. METHODS: The study was conducted in a 12-bed outpatient Oncology unit of a major teaching hospital 6 months following implementation of a commercial EMMS. In-depth semi-structured interviews were conducted with doctors, nurses and pharmacists using the system to assess usability. The UTAUT framework was used to analyse the results, which facilitated evaluation of interrelated aspects and provided a structured summary of user experience and usability factors. RESULTS: Direct cross-comparison between user groups illustrated that doctors and pharmacists were generally satisfied with the facilitating conditions (hardware and training), but had divergent perceptions of performance (automation, standardised protocols and communication and documented) and effort (mental and temporal demand) expectancy. In counterpoint, nurses were generally satisfied across all constructs. Prior experience using an alternative EMMS influenced performance and effort expectancy and was related to early dissatisfaction with the EMMS. Furthermore, whilst not originally designed for the healthcare setting, the flexibility of the UTAUT allowed for translation to the hospital environment. CONCLUSION: Nurses demonstrated overall satisfaction with the EMMS, whilst doctors and pharmacists perceived usability problems, particularly related to restricted automaticity and system complexity, which hindered perceived EMMS success. The study demonstrates the feasibility and utility of the UTAUT framework to evaluate usability of an EMMS for multiple user groups in the Oncology setting.

Structural and functional characterisation of human RNA helicase DHX8 provides insights into the mechanism of RNA-stimulated ADP release.

DHX8 is a crucial DEAH-box RNA helicase involved in splicing and required for the release of mature mRNA from the spliceosome. Here, we report the biochemical characterisation of full-length human DHX8 and the catalytically active helicase core DHX8Δ547, alongside crystal structures of DHX8Δ547 bound to ADP and a structure of DHX8Δ547 bound to poly(A)6 single-strand RNA. Our results reveal that DHX8 has an in vitro binding preference for adenine-rich RNA and that RNA binding triggers the release of ADP through significant conformational flexibility in the conserved DEAH-, P-loop and hook-turn motifs. We demonstrate the importance of R620 and both the hook-turn and hook-loop regions for DHX8 helicase activity and propose that the hook-turn acts as a gatekeeper to regulate the directional movement of the 3' end of RNA through the RNA-binding channel. This study provides an in-depth understanding of the activity of DHX8 and contributes insights into the RNA-unwinding mechanisms of the DEAH-box helicase family.

MIR21 Drives Resistance to Heat Shock Protein 90 Inhibition in Cholangiocarcinoma.

BACKGROUND & AIMS: Cholangiocarcinomas (CCA) are resistant to chemotherapy, so new therapeutic agents are needed. We performed a screen to identify small-molecule compounds that are active against CCAs. Levels of microRNA 21 (MIR21 or miRNA21) are increased in CCAs. We investigated whether miRNA21 mediates resistance of CCA cells and organoids to HSP90 inhibitors. METHODS: We performed a high-throughput screen of 484 small-molecule compounds to identify those that reduced viability of 6 human CCA cell lines. We tested the effects of HSP90 inhibitors on cells with disruption of the MIR21 gene, cells incubated with MIR21 inhibitors, and stable cell lines with inducible expression of MIR21. We obtained CCA biopsies from patients, cultured them as organoids (patient-derived organoids). We assessed their architecture, mutation and gene expression patterns, response to compounds in culture, and when grown as subcutaneous xenograft tumors in mice. RESULTS: Cells with IDH1 and PBRM1 mutations had the highest level of sensitivity to histone deacetylase inhibitors. HSP90 inhibitors were effective in all cell lines, irrespective of mutations. Sensitivity of cells to HSP90 inhibitors correlated inversely with baseline level of MIR21. Disruption of MIR21 increased cell sensitivity to HSP90 inhibitors. CCA cells that expressed transgenic MIR21 were more resistant to HSP90 inhibitors than cells transfected with control vectors; inactivation of MIR21 in these cells restored sensitivity to these agents. MIR21 was shown to target the DnaJ heat shock protein family (Hsp40) member B5 (DNAJB5). Transgenic expression of DNAJB5 in CCA cells that overexpressed MIR21 re-sensitized them to HSP90 inhibitors. Sensitivity of patient-derived organoids to HSP90 inhibitors, in culture and when grown as xenograft tumors in mice, depended on expression of miRNA21. CONCLUSIONS: miRNA21 appears to mediate resistance of CCA cells to HSP90 inhibitors by reducing levels of DNAJB5. HSP90 inhibitors might be developed for the treatment of CCA and miRNA21 might be a marker of sensitivity to these agents.

Characterisation of CCT271850, a selective, oral and potent MPS1 inhibitor, used to directly measure in vivo MPS1 inhibition vs therapeutic efficacy.

BACKGROUND: The main role of the cell cycle is to enable error-free DNA replication, chromosome segregation and cytokinesis. One of the best characterised checkpoint pathways is the spindle assembly checkpoint, which prevents anaphase onset until the appropriate attachment and tension across kinetochores is achieved. MPS1 kinase activity is essential for the activation of the spindle assembly checkpoint and has been shown to be deregulated in human tumours with chromosomal instability and aneuploidy. Therefore, MPS1 inhibition represents an attractive strategy to target cancers. METHODS: To evaluate CCT271850 cellular potency, two specific antibodies that recognise the activation sites of MPS1 were used and its antiproliferative activity was determined in 91 human cancer cell lines. DLD1 cells with induced GFP-MPS1 and HCT116 cells were used in in vivo studies to directly measure MPS1 inhibition and efficacy of CCT271850 treatment. RESULTS: CCT271850 selectively and potently inhibits MPS1 kinase activity in biochemical and cellular assays and in in vivo models. Mechanistically, tumour cells treated with CCT271850 acquire aberrant numbers of chromosomes and the majority of cells divide their chromosomes without proper alignment because of abrogation of the mitotic checkpoint, leading to cell death. We demonstrated a moderate level of efficacy of CCT271850 as a single agent in a human colorectal carcinoma xenograft model. CONCLUSIONS: CCT271850 is a potent, selective and orally bioavailable MPS1 kinase inhibitor. On the basis of in vivo pharmacodynamic vs efficacy relationships, we predict that more than 80% inhibition of MPS1 activity for at least 24 h is required to achieve tumour stasis or regression by CCT271850.

7-(Pyrazol-4-yl)-3H-imidazo[4,5-b]pyridine-based derivatives for kinase inhibition: Co-crystallisation studies with Aurora-A reveal distinct differences in the orientation of the pyrazole N1-substituent.

Introduction of a 1-benzyl-1H-pyrazol-4-yl moiety at C7 of the imidazo[4,5-b]pyridine scaffold provided 7a which inhibited a range of kinases including Aurora-A. Modification of the benzyl group in 7a, and subsequent co-crystallisation of the resulting analogues with Aurora-A indicated distinct differences in binding mode dependent upon the pyrazole N-substituent. Compounds 7a and 14d interact with the P-loop whereas 14a and 14b engage with Thr217 in the post-hinge region. These crystallographic insights provide options for the design of compounds interacting with the DFG motif or with Thr217.

What are incident reports telling us? A comparative study at two Australian hospitals of medication errors identified at audit, detected by staff and reported to an incident system.

OBJECTIVES: To (i) compare medication errors identified at audit and observation with medication incident reports; (ii) identify differences between two hospitals in incident report frequency and medication error rates; (iii) identify prescribing error detection rates by staff. DESIGN: Audit of 3291 patient records at two hospitals to identify prescribing errors and evidence of their detection by staff. Medication administration errors were identified from a direct observational study of 180 nurses administering 7451 medications. Severity of errors was classified. Those likely to lead to patient harm were categorized as 'clinically important'. SETTING: Two major academic teaching hospitals in Sydney, Australia. MAIN OUTCOME MEASURES: Rates of medication errors identified from audit and from direct observation were compared with reported medication incident reports. RESULTS: A total of 12 567 prescribing errors were identified at audit. Of these 1.2/1000 errors (95% CI: 0.6-1.8) had incident reports. Clinically important prescribing errors (n = 539) were detected by staff at a rate of 218.9/1000 (95% CI: 184.0-253.8), but only 13.0/1000 (95% CI: 3.4-22.5) were reported. 78.1% (n = 421) of clinically important prescribing errors were not detected. A total of 2043 drug administrations (27.4%; 95% CI: 26.4-28.4%) contained ≥ 1 errors; none had an incident report. Hospital A had a higher frequency of incident reports than Hospital B, but a lower rate of errors at audit. CONCLUSIONS: Prescribing errors with the potential to cause harm frequently go undetected. Reported incidents do not reflect the profile of medication errors which occur in hospitals or the underlying rates. This demonstrates the inaccuracy of using incident frequency to compare patient risk or quality performance within or across hospitals. New approaches including data mining of electronic clinical information systems are required to support more effective medication error detection and mitigation.

Targeting the PPM1D phenotype; 2,4-bisarylthiazoles cause highly selective apoptosis in PPM1D amplified cell-lines.

The metal-dependent phosphatase PPM1D (WIP1) is an important oncogene in cancer, with over-expression of the protein being associated with significantly worse clinical outcomes. In this communication we describe the discovery and optimization of novel 2,4-bisarylthiazoles that phenocopy the knockdown of PPM1D, without inhibiting its phosphatase activity. These compounds cause growth inhibition at nanomolar concentrations, induce apoptosis, activate p53 and display impressive cell-line selectivity. The results demonstrate the potential for targeting phenotypes in drug discovery when tackling challenging targets or unknown mechanisms.

An Analysis of Incident Reports Related to Electronic Medication Management: How They Change Over Time.

OBJECTIVE: Electronic medication management (EMM) systems have been shown to introduce new patient safety risks that were not possible, or unlikely to occur, with the use of paper charts. Our aim was to examine the factors that contribute to EMM-related incidents and how these incidents change over time with ongoing EMM use. METHODS: Incidents reported at 3 hospitals between January 1, 2010, and December 31, 2019, were extracted using a keyword search and then screened to identify EMM-related reports. Data contained in EMM-related incident reports were then classified as unsafe acts made by users and the latent conditions contributing to each incident. RESULTS: In our sample, 444 incident reports were determined to be EMM related. Commission errors were the most frequent unsafe act reported by users (n = 298), whereas workarounds were reported in only 13 reports. User latent conditions (n = 207) were described in the highest number of incident reports, followed by conditions related to the organization (n = 200) and EMM design (n = 184). Over time, user unfamiliarity with the system remained a key contributor to reported incidents. Although fewer articles to electronic transfer errors were reported over time, incident reports related to the transfer of information between different computerized systems increased as hospitals adopted more clinical information systems. CONCLUSIONS: Electronic medication management-related incidents continue to occur years after EMM implementation and are driven by design, user, and organizational conditions. Although factors contribute to reported incidents in varying degrees over time, some factors are persistent and highlight the importance of continuously improving the EMM system and its use.

Design, Synthesis, and Evaluation of Inhibitors of Hedgehog Acyltransferase.

Hedgehog signaling is involved in embryonic development and cancer growth. Functional activity of secreted Hedgehog signaling proteins is dependent on N-terminal palmitoylation, making the palmitoyl transferase Hedgehog acyltransferase (HHAT), a potential drug target and a series of 4,5,6,7-tetrahydrothieno[3,2-c]pyridines have been identified as HHAT inhibitors. Based on structural data, we designed and synthesized 37 new analogues which we profiled alongside 13 previously reported analogues in enzymatic and cellular assays. Our results show that a central amide linkage, a secondary amine, and (R)-configuration at the 4-position of the core are three key factors for inhibitory potency. Several potent analogues with low- or sub-µM IC50 against purified HHAT also inhibit Sonic Hedgehog (SHH) palmitoylation in cells and suppress the SHH signaling pathway. This work identifies IMP-1575 as the most potent cell-active chemical probe for HHAT function, alongside an inactive control enantiomer, providing tool compounds for validation of HHAT as a target in cellular assays.

Erratum: iTAG an optimized IMiD-induced degron for targeted protein degradation in human and murine cells.

[This corrects the article DOI: 10.1016/j.isci.2023.107059.].

What Goes Up, Must Come Down: A State-of-the-Art Electronic Health Record Downtime and Uptime Procedure in a Metropolitan Health Setting.

BACKGROUND: Electronic health records (EHRs) are used at most hospitals around the world, and downtime events are inevitable and common. Downtime represents a risky time for patients because patient information and critical EHR functionality are unavailable. Many institutions have used EHRs for years, with health professionals less likely to be familiar or comfortable with paper-based processes, resulting in an increased risk of errors during downtimes. There is currently limited guidance available on how to develop and operationalize downtime procedure at a local level. In this paper, we fill this gap by describing our state-of-the-art downtime and uptime procedure and its evaluation. METHOD: A district-wide downtime and uptime procedure was revised and standardized based on lessons learned from other health care organizations. The procedure outlines downtime and uptime preparations including downtime drills, downtime viewer auditing, and downtime education; downtime response including activating downtime and tracking patient changes; and uptime recovery including medication reconciliation and uptime documentation. IMPLEMENTATION: We implemented our new procedure across the district during an 8-hour planned downtime. A district downtime planning committee was formed, and a virtual command center was established to coordinate the downtime and uptime events. During downtime and uptime, onsite support was provided by the district's health informatics teams and clinicians. Data recovery was completed safely and efficiently with the revised uptime process. Following the event, we gathered staff feedback and reflections on implementing the procedure which highlighted its success but also revealed some areas for further improvement. CONCLUSION: In this paper, we describe a state-of-the-art EHR downtime and uptime procedure and lessons learned from its implementation. The implementation was successful with staff well prepared and information reconciled efficiently ensuring safe continuity of care. It was only through extensive planning, significant commitment, and engagement of all stakeholders that this outcome was possible.

Nurses' Medication Administration Workarounds when Using Electronic Systems: An Analysis of Safety Incident Reports.

Electronic medication management systems (EMMS) have been implemented in most acute care settings in Australia to reduce medication error rates. One of the key challenges related to the introduction of EMMS in hospitals is the uptake of informal "workarounds" by clinicians, including nurses. In this study, we aimed to examine one workaround in depth, nurses not documenting medication administration in the EMMS at the time of administration. We conducted a review of incident reports to identify the factors that contribute to this workaround occurring and the consequences or potential consequences of this workaround on patients. We identified a range of contributing factors, with factors relating to the user (e.g. nurses being time poor) occurring most frequently in incident reports. The most frequently seen consequence of this workaround was the patient receiving an additional dose. This research revealed that strategies to reduce the uptake of this workaround should consider user and organisational factors rather than just EMMS design alone.

Accuracy of best possible medication histories by pharmacy students: an observational study.

BACKGROUND: Medication reconciliation is an effective strategy to prevent medication errors upon hospital admission and requires obtaining a patient's best possible mediation history (BPMH). However, obtaining a BPMH is time-consuming and pharmacy students may assist pharmacists in this task. AIM: To evaluate the proportion of patients who have an accurate BPMH from the pharmacy student-obtained BPMH compared to the pharmacist-obtained BPMH. METHOD: Twelve final-year pharmacy students were trained to obtain BPMHs upon admission at 2 tertiary hospitals and worked in pairs. Each student pair completed one 8-h shift each week for 8 weeks. Students obtained BPMHs for patients taking 5 or more medications. A pharmacist then independently obtained and checked the student BPMH from the same patient for accuracy. Deviations were determined between student-obtained and pharmacist-obtained BMPH. An accurate BPMH was defined as only having no-or-low risk medication deviations. RESULTS: The pharmacy students took BPMHs for 91 patients. Of these, 65 patients (71.4%) had an accurate BPMH. Of the 1170 medications included in patients' BPMH, 1118 (95.6%) were deemed accurate. For the student-obtained BPMHs, they were more likely to be accurate for patients who were older (OR 1.04; 95% CI 1.03-1.06; p < 0.001), had fewer medications (OR 0.85; 95% CI 0.75-0.97; p = 0.02), and if students used two source types (administration and supplier) to obtain the BPMH (OR 1.65; 95% CI 1.09-2.50; p = 0.02). CONCLUSION: It is suitable for final-year pharmacy students to be incorporated into the BPMHs process and for their BPMHs to be verified for accuracy by a pharmacist.

Discovery of 2-(3-Benzamidopropanamido)thiazole-5-carboxylate Inhibitors of the Kinesin HSET (KIFC1) and the Development of Cellular Target Engagement Probes.

The existence of multiple centrosomes in some cancer cells can lead to cell death through the formation of multipolar mitotic spindles and consequent aberrant cell division. Many cancer cells rely on HSET (KIFC1) to cluster the extra centrosomes into two groups to mimic the bipolar spindle formation of non-centrosome-amplified cells and ensure their survival. Here, we report the discovery of a novel 2-(3-benzamidopropanamido)thiazole-5-carboxylate with micromolar in vitro inhibition of HSET (KIFC1) through high-throughput screening and its progression to ATP-competitive compounds with nanomolar biochemical potency and high selectivity against the opposing mitotic kinesin Eg5. Induction of the multipolar phenotype was shown in centrosome-amplified human cancer cells treated with these inhibitors. In addition, a suitable linker position was identified to allow the synthesis of both fluorescent- and trans-cyclooctene (TCO)-tagged probes, which demonstrated direct compound binding to the HSET protein and confirmed target engagement in cells, through a click-chemistry approach.

Determination of Ligand-Binding Affinity (Kd) Using Transverse Relaxation Rate (R2) in the Ligand-Observed 1H NMR Experiment and Applications to Fragment-Based Drug Discovery.

High hit rates from initial ligand-observed NMR screening can make it challenging to prioritize which hits to follow up, especially in cases where there are no available crystal structures of these hits bound to the target proteins or other strategies to provide affinity ranking. Here, we report a reproducible, accurate, and versatile quantitative ligand-observed NMR assay, which can determine Kd values of fragments in the affinity range of low µM to low mM using transverse relaxation rate R2 as the observable parameter. In this study, we examined the theory and proposed a mathematical formulation to obtain Kd values using non-linear regression analysis. We designed an assay format with automated sample preparation and simplified data analysis. Using tool compounds, we explored the assay reproducibility, accuracy, and detection limits. Finally, we used this assay to triage fragment hits, yielded from fragment screening against the CRBN/DDB1 complex.

iTAG an optimized IMiD-induced degron for targeted protein degradation in human and murine cells.

To address the limitation associated with degron based systems, we have developed iTAG, a synthetic tag based on IMiDs/CELMoDs mechanism of action that improves and addresses the limitations of both PROTAC and previous IMiDs/CeLMoDs based tags. Using structural and sequence analysis, we systematically explored native and chimeric degron containing domains (DCDs) and evaluated their ability to induce degradation. We identified the optimal chimeric iTAG(DCD23 60aa) that elicits robust degradation of targets across cell types and subcellular localizations without exhibiting the well documented "hook effect" of PROTAC-based systems. We showed that iTAG can also induce target degradation by murine CRBN and enabled the exploration of natural neo-substrates that can be degraded by murine CRBN. Hence, the iTAG system constitutes a versatile tool to degrade targets across the human and murine proteome.

Discovery of an In Vivo Chemical Probe for BCL6 Inhibition by Optimization of Tricyclic Quinolinones.

B-cell lymphoma 6 (BCL6) is a transcriptional repressor and oncogenic driver of diffuse large B-cell lymphoma (DLBCL). Here, we report the optimization of our previously reported tricyclic quinolinone series for the inhibition of BCL6. We sought to improve the cellular potency and in vivo exposure of the non-degrading isomer, CCT373567, of our recently published degrader, CCT373566. The major limitation of our inhibitors was their high topological polar surface areas (TPSA), leading to increased efflux ratios. Reducing the molecular weight allowed us to remove polarity and decrease TPSA without considerably reducing solubility. Careful optimization of these properties, as guided by pharmacokinetic studies, led to the discovery of CCT374705, a potent inhibitor of BCL6 with a good in vivo profile. Modest in vivo efficacy was achieved in a lymphoma xenograft mouse model after oral dosing.

Effects of two commercial electronic prescribing systems on prescribing error rates in hospital in-patients: a before and after study.

BACKGROUND: Considerable investments are being made in commercial electronic prescribing systems (e-prescribing) in many countries. Few studies have measured or evaluated their effectiveness at reducing prescribing error rates, and interactions between system design and errors are not well understood, despite increasing concerns regarding new errors associated with system use. This study evaluated the effectiveness of two commercial e-prescribing systems in reducing prescribing error rates and their propensities for introducing new types of error. METHODS AND RESULTS: We conducted a before and after study involving medication chart audit of 3,291 admissions (1,923 at baseline and 1,368 post e-prescribing system) at two Australian teaching hospitals. In Hospital A, the Cerner Millennium e-prescribing system was implemented on one ward, and three wards, which did not receive the e-prescribing system, acted as controls. In Hospital B, the iSoft MedChart system was implemented on two wards and we compared before and after error rates. Procedural (e.g., unclear and incomplete prescribing orders) and clinical (e.g., wrong dose, wrong drug) errors were identified. Prescribing error rates per admission and per 100 patient days; rates of serious errors (5-point severity scale, those ≥3 were categorised as serious) by hospital and study period; and rates and categories of postintervention "system-related" errors (where system functionality or design contributed to the error) were calculated. Use of an e-prescribing system was associated with a statistically significant reduction in error rates in all three intervention wards (respectively reductions of 66.1% [95% CI 53.9%-78.3%]; 57.5% [33.8%-81.2%]; and 60.5% [48.5%-72.4%]). The use of the system resulted in a decline in errors at Hospital A from 6.25 per admission (95% CI 5.23-7.28) to 2.12 (95% CI 1.71-2.54; p<0.0001) and at Hospital B from 3.62 (95% CI 3.30-3.93) to 1.46 (95% CI 1.20-1.73; p<0.0001). This decrease was driven by a large reduction in unclear, illegal, and incomplete orders. The Hospital A control wards experienced no significant change (respectively -12.8% [95% CI -41.1% to 15.5%]; -11.3% [-40.1% to 17.5%]; -20.1% [-52.2% to 12.4%]). There was limited change in clinical error rates, but serious errors decreased by 44% (0.25 per admission to 0.14; p = 0.0002) across the intervention wards compared to the control wards (17% reduction; 0.30-0.25; p = 0.40). Both hospitals experienced system-related errors (0.73 and 0.51 per admission), which accounted for 35% of postsystem errors in the intervention wards; each system was associated with different types of system-related errors. CONCLUSIONS: Implementation of these commercial e-prescribing systems resulted in statistically significant reductions in prescribing error rates. Reductions in clinical errors were limited in the absence of substantial decision support, but a statistically significant decline in serious errors was observed. System-related errors require close attention as they are frequent, but are potentially remediable by system redesign and user training. Limitations included a lack of control wards at Hospital B and an inability to randomize wards to the intervention.