Linear peptides can mimic and disrupt protein-protein interactions involved in critical cell signaling pathways. Such peptides however are usually protease sensitive and unable to engage with intracellular targets due to lack of membrane permeability. Peptide stapling has been proposed to circumvent these limitations but recent data has suggested that this method does not universally solve the problem of cell entry and can lead to molecules with off target cell lytic properties. To address these issues a library of stapled peptides was synthesized and screened to identify compounds that bound Mdm2 and activated cellular p53. A lead peptide was identified that activated intracellular p53 with negligible nonspecific cytotoxicity, however it still bound serum avidly and only showed a marginal improvement in cellular potency. These hurdles were overcome by successfully identifying a pyridinium-based cationic lipid formulation, which significantly improved the activity of the stapled peptide in a p53 reporter cell line, principally through increased vesicular escape. These studies underscore that stapled peptides, which are cell permeable and target specific, can be identified with rigorous experimental design and that these properties can be improved through use with lipid based formulations. This work should facilitate the clinical translation of stapled peptides.
Background Dosing regimens guided by therapeutic drug monitoring (TDM) may be able to improve penicillin exposure in patients, which could result in improved patient health outcomes. Objectives This systematic review aims to describe the impact penicillin TDM has on health outcomes, including antimicrobial resistance (AMR). Methods Studies measuring penicillins in patient samples that adjusted regimens according to the result, and reported health outcomes were selected. Study bias was assessed according to study type. Included study characteristics were tabulated and described by narrative synthesis. Results Three randomized controlled trials (RCTs), 16 cohort studies, and 9 case studies were included. No RCTs showed statistically significant improvements in health outcomes. Five cohort studies showed improvement in at least one health outcome associated with target attainment. However, there was a high risk of bias in all studies for health outcomes. One study assessed the impact of penicillin TDM on AMR and found that improved target attainment was associated with suppression of resistance. No studies found a detrimental effect of penicillin TDM. Conclusions There is little evidence to suggest that TDM improves health outcomes, however neither health outcomes nor impact on AMR were adequately addressed. Variations in TDM implementation meant that a meta-analysis was not suitable. Penicillin TDM needs standardization, however there is currently no clear evidence of optimal conditions. Suitably powered studies are required to resolve the ambiguity surrounding the impact of TDM on clinical outcomes, including AMR. Further, standardized protocols and concentration targets need to be identified for TDM to be implemented successfully.
Adjusting dosing regimens based on measurements of carbapenem levels may improve carbapenem exposure in patients. This systematic review aims to describe the effect carbapenem therapeutic drug monitoring (TDM) has on health outcomes, including the emergence of antimicrobial resistance (AMR). Four databases were searched for studies that reported health outcomes following adjustment to dosing regimens, according to measurements of carbapenem concentration. Bias in the studies was assessed with risk of bias analysis tools. Study characteristics and outcomes were tabulated and a narrative synthesis was performed. In total, 2 randomised controlled trials (RCTs), 17 non-randomised studies, and 19 clinical case studies were included. Significant variation in TDM practice was seen; consequently, a meta-analysis was unsuitable. Few studies assessed impacts on AMR. No significant improvement on health outcomes and no detrimental effects of carbapenem TDM were observed. Five cohort studies showed significant associations between achieving target concentrations and clinical success, including suppression of resistance. Studies in this review showed no obvious improvement in clinical outcomes when TDM is implemented. Optimisation and standardisation of carbapenem TDM practice are needed to improve intervention success and enable study synthesis. Further suitably powered studies of standardised TDM are required to assess the impact of TMD on clinical outcomes and AMR.
Background Dosing regimens guided by therapeutic drug monitoring (TDM) may be able to improve penicillin exposure in patients. Improved penicillin exposure could result in improved patient health outcomes. This systematic review aims to describe the impact TDM in penicillin treatment has on health outcomes, including the emergence of antimicrobial resistance (AMR). Methods A search of four databases was conducted and supplemented with a hand search of the literature. Studies that measured concentrations of penicillins in patients, adjusted dosing regimens according to the result and reported health outcomes were selected. The risk of bias was assessed according to study type: randomized controlled trials (RCTs) were assessed with the revised Cochrane risk-of-bias tool for randomized trials (RoB2) assessment tool, the risk of bias in non-randomized studies (ROBINS-1) assessment tool was used to assess observational studies, and the Office of Health Assessment and Translation (OHAT) tool was used to assess case studies. The study characteristics were tabulated and described using a narrative synthesis. Results Three RCTs, 16 observational cohort studies and 9 case studies were included. None of the studies showed statistically significant improvements in health outcomes, when comparing groups receiving TDM and standard care. Five observational studies showed improvement in at least one health outcome statistically significantly associated with target attainment: mortality,1–5 bacterial persistence,1,4,5 ICU length of stay,4 treatment efficacy,1,4,6 and suppression of AMR.4 However there was a high risk of bias in all of these studies for health outcomes. Most had pharmacological primary outcomes and were underpowered to detect health outcomes. All three RCTs and four (25%) observational studies found that the use of penicillin TDM was associated with improved pharmacological target attainment. Only one study was found that assessed the impact of β-lactams TDM on AMR and found that target attainment of 100% ƒT>4×MIC was significantly associated with suppression of resistance. No studies found a detrimental effect of penicillin TDM on health outcomes. A meta-analysis was not performed due to the heterogeneity of the included studies. Conclusions There is little evidence to suggest that TDM improves health outcomes, however neither health outcomes nor reductions in emergence of AMR were adequately addressed by currently published studies. The evaluation of health outcomes was not the primary aim of the majority of the included studies, consequently those that did include these outcomes were underpowered to detect a difference. Observational studies often did not take into account co-interventions, or confounding factors, resulting in a high risk of bias. Large variations in how TDM of penicillins was implemented and the different populations used meant that a quantitative synthesis of results was not suitable. Recommendations to standardize penicillin TDM are a challenge currently, as there is no clear evidence of optimal conditions. Suitably powered studies designed to assess clinical outcomes are required to resolve the ambiguity surrounding the impacts of TDM on clinical outcomes, and to address the gap of the impacts on AMR. Further, appropriate standardized protocols and concentration targets for penicillin TDM in humans need to be identified for it to be implemented successfully.
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