ABSTRACT:We previously reported the discovery of VU0364572 and VU0357017 as M 1 -selective agonists that appear to activate M 1 through actions at an allosteric site. Previous studies have revealed that chemical scaffolds for many allosteric modulators contain molecular switches that allow discovery of allosteric antagonists and allosteric agonists or positive allosteric modulators (PAMs) based on a single chemical scaffold. Based on this, we initiated a series of studies to develop selective M 1 allosteric antagonists based on the VU0364572 scaffold. Interestingly, two lead antagonists identified in this series, VU0409774 and VU0409775, inhibited ACh-induced Ca 2+ responses at rat M 1−5 receptor subtypes, suggesting they are nonselective muscarinic antagonists. VU0409774 and VU0409775 also completely displaced binding of the nonselective radioligand [3 H]-NMS at M 1 and M 3 mAChRs with affinities similar to their functional IC 50 values. Finally, Schild analysis revealed that these compounds inhibit M 1 responses through a fully competitive interaction at the orthosteric binding site. This surprising finding prompted further studies to determine whether agonist activity of VU0364572 and VU0357017 may also engage in previously unappreciated actions at the orthosteric site on M 1 . Surprisingly, both VU0364572 and VU0357017 completely displaced [ 3 H]-NMS binding to the orthosteric site of M 1 −M 5 receptors at high concentrations. Furthermore, evaluation of agonist activity in systems with varying levels of receptor reserve and Furchgott analysis using a cell line expressing M 1 under control of an inducible promotor was consistent with an action of these compounds as weak orthosteric partial agonists of M 1 . However, consistent with previous studies suggesting actions at a site that is distinct from the orthosteric binding site, VU0364572 or VU0357017 slowed the rate of [ 3 H]-NMS dissociation from CHOrM 1 membranes. Together, these results suggest that VU0364572 and VU0357017 act as bitopic ligands and that novel antagonists in this series act as competitive orthosteric site antagonists.

Background: Drug change (DC) is a common challenge in Danish hospitals. It affects the work of hospital personnel and has potentially serious patient safety consequences. Focus on medication safety is becoming increasingly important in the prevention of adverse events. The aim of this study is to identify and describe patient safety challenges related to DCs, and to explore potential facilitators to improve patient safety in the medication process in Danish hospital setting. Method: Two qualitative methods were combined. Data were obtained from the Danish Patient Safety Database (DPSD) containing incidents reports of adverse events related to DCs. Additionally, five semi-structured focus group interviews with hospital personnel (doctors, nurses, pharmacists and pharmacy technicians) from the five regions of Denmark were held. Results: The DPSD search identified 88 incidents related to DCs due to tender or drug shortage. The incidents were linked to prescribing errors, incorrect dose being dispensed/administered, and delayed/omitted treatment. Four themes from the interviews emerged: (1) challenges related to the drug itself; (2) situational challenges; (3) challenges related to the organization/IT systems/personnel; (4) facilitators/measures to ensure patient safety. Conclusion: DC is as a complex challenge, especially related to drug shortage. The results allow for a deeper understanding of the challenges and possible facilitators of DCs on the individual and organizational level. Pharmacy personnel were identified to play a key role in ensuring patient safety of DCs in hospitals. Indeed, this emphasizes that pharmacy personnel should be engaged in developing patient safety strategies and support hospital personnel around drug changes.

This letter describes the further exploration of two series of M1allosteric agonists, TBPB and VU0357017, previously reported from our lab. Within the TPBP scaffold, either electronic or steric perturbations to the central piperidine ring led to a loss of selective M1 allosteric agonism and afforded pan-mAChR antagonism, which was demonstrated to be mediated via the orthosteric site. Additional SAR around a related M1 allosteric agonist family (VU0357017) identified similar, subtle ‘molecular switches’ that modulated modes of pharmacology from allosteric agonism to pan-mAChR orthosteric antagonism. Therefore, all of these ligands are best classified as bi-topic ligands that possess high affinity binding at an allosteric site to engender selective M1 activation, but all bind, at higher concentrations, to the orthosteric ACh site, leading to non-selective orthosteric site binding and mAChR antagonism.

This Letter describes the continued optimization of an MLPCN probe molecule M1 antagonist (ML012) through an iterative parallel synthesis approach. After several rounds of modifications of the parent compound, we arrived at a new azetidine scaffold that displayed improved potency while maintaining a desirable level of selectivity over other muscarinic receptor subtypes. Data for representative molecules 7w (VU0452865) and 12a (VU0455691) are presented.

Utilizing a combination of high-throughput and multi-step synthesis, SAR in a novel series of M1 acetylcholine receptor antagonists was rapidly established. The efforts led to the discovery the highly potent M1 antagonists 6 (VU0431263), and 8f (VU0433670). Functional Schild analysis and radioligand displacement experiments demonstrated the competitive, orthosteric binding of these compounds; human selectivity data are presented.