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A novel series of potent benzoxazole mPGES-1 inhibitors has been derived from a hit from a high throughput screen. Compound 37 displays mPGES-1 inhibition in an enzyme assay (0.018 μM) and PGE-2 inhibition in a cell-based assay (0.034 μM). It demonstrates 500- and 2500-fold selectivity for mPGES-1 over COX-2 and 6-keto PGF-1α, respectively. In vivo PK studies in dogs demonstrate 55% oral bioavailability and an 7 h half-life., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Dietary proteins are mostly absorbed as di- and tripeptides by the intestinal proton-dependent transporter PepT1. We have examined the effects of leptin on PepT1 function in rat jejunum and in monolayers of the human enterocyte-like 2 cell Caco-2. Leptin is produced by the stomach and secreted in the gut lumen. We show here that PepT1 and leptin receptors are expressed in Caco-2 and rat intestinal mucosal cells. Apical (but not basolateral) leptin increased Caco-2 cell transport of cephalexin (CFX) and glycylsarcosine (Gly-Sar), an effect that was associated with increased Gly-Sar uptake, increased membrane PepT1 protein, decreased intracellular PepT1 content, and no change in PepT1 mRNA levels. The maximal velocity (Vmax) for Gly-Sar transport was significantly increased by leptin, whereas the apparent Michaelis-Menten constant (Km) did not change. Furthermore, leptin-stimulated Gly-Sar transport was completely suppressed by colchicine, which disrupts cellular translocation of proteins to plasma membranes. Intrajejunal leptin also induced a rapid twofold increase in plasma CFX after jejunal perfusion with CFX in the rat, indicating enhanced intestinal absorption of CFX. These data revealed an unexpected action of gastric leptin in controlling ingestion of dietary proteins.

Di- and tripeptides, as well as peptidomimetic drugs such as cephalexin (CFX), are absorbed by enterocytes via the oligopeptide transporter PepT1. We recently showed that the alpha(2)-adrenergic agonist clonidine increases CFX absorption in anaesthetized rats. Herein, we investigated whether alpha(2)-adrenergic receptors can directly affect PepT1 activity in a clone of the differentiated human intestinal cell line Caco-2 (Caco-2 3B) engineered to stably express alpha(2A)-adrenergic receptors at a density similar to that found in normal mucosa. Measurement of CFX fluxes across cell monolayers cultured on transwell filters demonstrated that the alpha(2)-agonists clonidine and UK14304 caused a 2-fold increase of CFX transport in Caco-2 3B cells, but not in Caco-2 (expressing PepT1 but not alpha(2)-adrenergic receptors) or in the HT29 19A clone (expressing alpha(2)-adrenergic receptors but not PepT1). The stimulatory effect of clonidine was abolished by glycyl-sarcosine (a competitor for the transporter) and blocked by yohimbine or RX821002 (alpha(2)-antagonists). Analysis of the kinetics of CFX transport in control and clonidine-treated Caco-2 3B cells showed that clonidine increased V(max) of CFX transport without changing K(m). Clonidine action was abolished by colchicine but not altered by amiloride, demonstrating that microtubule integrity but not Na(+)/H(+) exchanger activity is necessary for the effect of alpha(2)-agonists to occur. In conclusion, clonidine can directly activate alpha(2)-adrenergic receptors located on epithelial cells. The precise molecular mechanisms whereby these receptors modulate PepT1 activity remain to be elucidated but an increased translocation to the apical membrane of preformed cytoplasmic transporter molecules is likely to be involved.

Intestinal absorption of beta-lactamine antibiotics (e.g., cefixime and cephalexin) has been shown to proceed through the dipeptide carrier system. In a previous study, nifedipine (NFP), an L-type calcium channel blocker, enhanced the absorption of cefixime in vivo but not in vitro, and it was suggested that neural mechanisms might be involved in the effect of NFP. The aim of the present study was to assess the involvement of the nervous system on the intestinal absorption of cephalexin (CFX). To investigate this, we used a single-pass jejunal perfusion technique in rats. NFP and diltiazem enhanced approximately 2-fold the plasma levels of CFX in treated rats versus untreated controls. NFP also increased approximately 2-fold the CFX level in portal plasma and increased urinary excretion of CFX, thus indicating that CFX did effectively increase CFX intestinal absorption. Perfusing high concentrations of dipeptides in the jejunal lumen competitively reduced CFX absorption and inhibited the enhancement of CFX absorption produced by NFP. Hexamethonium and lidocaine inhibited the effect of NFP, whereas atropine, capsaicin, clonidine, and isoproterenol enhanced CFX absorption by the same order of magnitude as NFP. Thus, complex neural networks can modulate the function of the intestinal di- and tripeptide transporter. Sympathetic noradrenergic fibers, intestinal sensory neurons, and nicotinic synapses are involved in the increase of CFX absorption produced by NFP.

Itraconazole is a new oral triazole antifungal agent that is effective against a wide range of fungal pathogens, including Aspergillus species. There has been a considerable increase in recent years in its use in prophylaxis of aspergillosis in neutropenic patients. A total of 74 trough concentrations of itraconazole+active metabolite were retrospectively analysed at steady state in 16 patients admitted to hospital for acute myeloid leukaemia (12) or malignant lymphoma (4). The minimum therapeutic concentration (itraconazole+hydroxyitraconazole = 1000 ng/ml) was never reached in 31 per cent of patients (5/16) and a constant efficient plasma concentration was obtained in only 19 per cent (3/16) with a daily regimen of 400-600 mg. The plasma levels of patients at the same daily dose differed up to 15-fold. This study confirms the pronounced inter-patient variability of unchanged itraconazole concentrations previously found in volunteers and patients. The plasma levels in six patients during successive chemotherapy treatments also varied greatly. Intra-individual differences were more accurately examined in six patients given 600 mg itraconazole/day during their first chemotherapy treatment. The trough plasma concentrations on day 15 and day 25 varied from -53 to +245 per cent. These results indicate that the plasma itraconazole concentration of neutropenic patients must be monitored to ensure that each individual is given a clinically effective dose.