Ivacaftor pharmacokinetics and lymphatic transport after enteral administration in rats.

Background: Ivacaftor is a modern drug used in the treatment of cystic fibrosis. It is highly lipophilic and exhibits a strong positive food effect. These characteristics can be potentially connected to a pronounced lymphatic transport after oral administration. Methods: A series of studies was conducted to describe the basic pharmacokinetic parameters of ivacaftor in jugular vein cannulated rats when dosed in two distinct formulations: an aqueous suspension and an oil solution. Additionally, an anesthetized mesenteric lymph duct cannulated rat model was studied to precisely assess the extent of lymphatic transport. Results: Mean ± SD ivacaftor oral bioavailability was 18.4 ± 3.2% and 16.2 ± 7.8%, respectively, when administered as an aqueous suspension and an oil solution. The relative contribution of the lymphatic transport to the overall bioavailability was 5.91 ± 1.61% and 4.35 ± 1.84%, respectively. Conclusion: Lymphatic transport plays only a minor role in the process of ivacaftor intestinal absorption, and other factors are, therefore, responsible for its pronounced positive food effect.

Pharmacological effects of mTORC1/C2 inhibitor in a preclinical model of NASH progression.

Knowledge of the benefits of mTOR inhibition concerning adipogenesis and inflammation has recently encouraged the investigation of a new generation of mTOR inhibitors for non-alcoholic steatohepatitis (NASH). We investigated whether treatment with a specific mTORC1/C2 inhibitor (Ku-0063794; KU) exerted any beneficial impacts on experimentally-induced NASH in vitro and in vivo. The results indicated that KU decreases palmitic acid-induced lipotoxicity in cultivated primary hepatocytes, thus emerging as a successful candidate for testing in an in vivo NASH dietary model, which adopted the intraperitoneal KU dosing route rather than oral application due to its significantly greater bioavailability in mice. The pharmacodynamics experiments commenced with the feeding of male C57BL/6 mice with a high-fat atherogenic western-type diet (WD) for differing intervals over several weeks aimed at inducing various phases of NASH. In addition to the WD, the mice were treated with KU for 3 weeks or 4 months. Acute and chronic KU treatments were observed to be safe at the given concentrations with no toxicity indications in the mice. KU was found to alleviate NASH-related hepatotoxicity, mitochondrial and oxidative stress, and decrease the liver triglyceride content and TNF-α mRNA in at least one set of in vivo experiments. The KU modulated liver expression of selected metabolic and oxidative stress-related genes depended upon the length and severity of the disease. Although KU failed to completely reverse the histological progression of NASH in the mice, we demonstrated the complexity of mTORC1/C2 signaling regulation and suggest a stratified therapeutic management approach throughout the disease course.

Differentiated modulation of signaling molecules AMPK and SIRT1 in experimentally drug-induced hepatocyte injury.

AIM: Currently available medicines have little to offer in terms of supporting the regeneration of injured hepatic cells. Previous experimental studies have shown that resveratrol and metformin, less specific activators of AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1), can effectively attenuate acute liver injury. The aim of this experimental study was to elucidate whether modulation of AMPK and SIRT1 activity can modify drug/paracetamol (APAP)-induced hepatocyte damage in vitro. METHODS: Primary rat hepatocytes were pretreated with mutual combinations of specific synthetic activators and inhibitors of SIRT1 and AMPK and followed by a toxic dose of APAP. At the end of cultivation, medium samples were collected for biochemical analysis of alanine-aminotransferase and nitrite levels. Hepatocyte viability, thiobarbituric reactive substances, SIRT1 and AMPK activity and protein expression were also assessed. RESULTS: The harmful effect of APAP was associated with decreased AMPK and SIRT1 activity and protein expression alongside enhanced oxidative stress in hepatocytes. The addition of AMPK activator (AICAR) or SIRT1 activator (CAY10591) significantly attenuated the deleterious effects of AMPK inhibitor (Compound C) on the hepatotoxicity of APAP. Furthermore, CAY10591 but not AICAR markedly decreased the deleterious effect of APAP in combination with SIRT1 inhibitor (EX-527). CONCLUSION: Our findings demonstrate that decreased AMPK activity is associated with the hepatotoxic effect of APAP which can be significantly attenuated by the administration of a SIRT1 activator. These findings suggest that differentiated modulation of AMPK and SIRT1 activity could therefore provide an interesting and novel therapeutic opportunity in the future to combat hepatocyte injury.

Statins and liver.

Statins are widely accepted hypolipidemics that work by inhibiting hydroxymethylglutaryl coenzyme A reductase and thereby inhibiting cholesterol synthesis. They significantly reduce cardiovascular risk. Their use could be associated with side effects, which are serious only in rare cases. However, an unhealthy lifestyle, obesity, and elevation of blood lipids do not only damage the cardiovascular system. The current topic not only in hepatology is non-alcoholic fatty liver disease - NAFLD. The aim of this article is, among others, to draw attention to the pleiotropic effects of statins, which could be used in the treatment of this disease in the future. Recent studies have suggested that the administration of statins to patients with NAFLD is beneficial.

mTOR as an eligible molecular target for possible pharmacological treatment of nonalcoholic steatohepatitis.

Currently, non-alcoholic fatty liver disease (NAFLD) progressing into chronic non-alcoholic steatohepatitis (NASH), liver cirrhosis, and eventually hepatocellular cancer has emerged as an epidemiological concern due to lack of proven treatment. Our review briefly comprises of the mechanism of pathogenesis and inflammation corresponding to the disease, and all the offered insights of mechanistic pathways that could be targeted in the progression of NASH. The review principally focuses on mTOR (mammalian target of rapamycin) as a promising target highlighting its immense role in lipogenesis and alleviating inflammation and fibrosis. A detailed description of signaling pathways of mTORC1 and mTORC2 that are inhibited by rapamycin and other mTOR inhibitor analogues is accentuated. The exploration of mTOR inhibitors clearly explains the exigent molecular aspects of mTOR in regulating adipocyte and lipogenic marker genes (e.g. those encoding PPARγ, SREBP1c). The literature on available mTOR inhibitors and their classification so far could be extremely useful in highlighting mTOR as a favorable drug target in the indication of NASH in the near future.