Investigating Nephrotoxicity of Polymyxin Derivatives by Mapping Renal Distribution Using Mass Spectrometry Imaging

Colistin and polymyxin B are effective treatment options for Gram-negative resistant bacteria but are used as last-line therapy due to their dose-limiting nephrotoxicity. A critical factor in developing safer polymyxin analogues is understanding accumulation of the drugs and their metabolites, which is currently limited due to the lack of effective techniques for analysis of these challenging molecules. Mass spectrometry imaging (MSI) allows direct detection of targets (drugs, metabolites, and endogenous compounds) from tissue sections. The presented study exemplifies the utility of MSI by measuring the distribution of polymyxin B1, colistin, and polymyxin B nonapeptide (PMBN) within dosed rat kidney tissue sections. The label-free MSI analysis revealed that the nephrotoxic compounds (polymyxin B1 and colistin) preferentially accumulated in the renal cortical region. The less nephrotoxic analogue, polymyxin B nonapeptide, was more uniformly distributed throughout the kidney. In addition, metabolites of the dosed compounds were detected by MSI. Kidney homogenates were analyzed using LC/MS/MS to determine total drug exposure and for metabolite identification. To our knowledge, this is the first time such techniques have been utilized to measure the distribution of polymyxin drugs and their metabolites. By simultaneously detecting the distribution of drug and drug metabolites, MSI offers a powerful alternative to tissue homogenization analysis and label or antibody-based imaging

Optimization of Brain Penetrant 11β-Hydroxysteroid Dehydrogenase Type I Inhibitors and in Vivo Testing in Diet-Induced Obese Mice

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) has been widely considered by the pharmaceutical industry as a target to treat metabolic syndrome in type II diabetics. We hypothesized that central nervous system (CNS) penetration might be required to see efficacy. Starting from a previously reported pyrimidine compound, we removed hydrogen-bond donors to yield <b>3</b>, which had modest CNS penetration. More significant progress was achieved by changing the core to give <b>40</b>, which combines good potency and CNS penetration. Compound <b>40</b> was dosed to diet-induced obese (DIO) mice and gave excellent target engagement in the liver and high free exposures of drug, both peripherally and in the CNS. However, no body weight reduction or effects on glucose or insulin were observed in this model. Similar data were obtained with a structurally diverse thiazole compound <b>51</b>. This work casts doubt on the hypothesis that localized tissue modulation of 11β-HSD1 activity alleviates metabolic syndrome

Novel Acidic 11β-Hydroxysteroid Dehydrogenase Type 1 (11β-HSD1) Inhibitor with Reduced Acyl Glucuronide Liability: The Discovery of 4‑[4-(2-Adamantylcarbamoyl)-5-<i>tert</i>-butyl-pyrazol-1-yl]benzoic Acid (AZD8329)

Inhibition of 11β-HSD1 is viewed as a potential target for the treatment of obesity and other elements of the metabolic syndrome. We report here the optimization of a carboxylic acid class of inhibitors from AZD4017 (<b>1</b>) to the development candidate AZD8329 (<b>27</b>). A structural change from pyridine to pyrazole together with structural optimization led to an improved technical profile in terms of both solubility and pharmacokinetics. The extent of acyl glucuronidation was reduced through structural optimization of both the carboxylic acid and amide substituents, coupled with a reduction in lipophilicity leading to an overall increase in metabolic stability

Discovery of a Potent, Selective, and Orally Bioavailable Acidic 11β-Hydroxysteroid Dehydrogenase Type 1 (11β-HSD1) Inhibitor: Discovery of 2-[(3<i>S</i>)-1-[5-(Cyclohexylcarbamoyl)-6-propylsulfanylpyridin-2-yl]-3-piperidyl]acetic Acid (AZD4017)

Inhibition of 11β-HSD1 is an attractive mechanism for the treatment of obesity and other elements of the metabolic syndrome. We report here the discovery of a nicotinic amide derived carboxylic acid class of inhibitors that has good potency, selectivity, and pharmacokinetic characteristics. Compound <b>11i</b> (AZD4017) is an effective inhibitor of 11β-HSD1 in human adipocytes and exhibits good druglike properties and as a consequence was selected for clinical development