Novel tricyclic-alpha-alkyloxyphenylpropionic acids: dual PPARalpha/gamma agonists with hypolipidemic and antidiabetic activity

Synthesis and structure-activity relationships of tricyclic alpha-ethoxy-phenylpropionic acid derivatives guided by in vitro PPARalpha and PPARgamma transactivation data and computer modeling led to the identification of the novel carbazole analogue, 3q, with dual PPARalpha (EC(50) = 0.36 microM) and PPARgamma (EC(50) = 0.17 microM) activity in vitro. Ten days treatment of db/db mice with 3q improved the insulin sensitivity, as measured by OGTT, better than that seen with both pioglitazone and rosiglitazone treatment, suggesting in vivo PPARgamma activity. Likewise, 3q lowered plasma triglycerides and cholesterol in high cholesterol fed rats after 4 days treatment, indicating in vivo PPARalpha activity. Investigations of the pharmacokinetics of selected compounds suggested that extended drug exposure improved the in vivo activity of in vitro active compounds.     

Platelet activation, and antiplatelet targets and agents: current and novel strategies

Platelets play a key role in thrombosis and haemostasis, which can be either beneficial or deleterious depending on the circumstances. Multiple factors, such as genetic polymorphisms, pathological state and lifestyle, are thought to be associated with platelet hyperreactivity. Platelet activation occurs through the complex process of transmembrane signalling, with a cascade of biochemical interactions leading to platelet activation. Transmembrane signalling involves many different molecules with different enzymatic activity and/or function. Based on the signalling pathways involved in platelet activation, there are four possible targets of antiplatelet drugs: (i) inhibition of agonist generation; (ii) receptor inhibition; (iii) G-protein inhibition; and (iv) inhibition of enzymatic cascades. However, both established and novel antiplatelet drugs have their own advantages and disadvantages. Because of the problems associated with the use of current antiplatelet drugs, such as resistance, optimal dosage and safety, future strategies for the development of new antiplatelet drugs and new treatment regimens may include consideration of the following: (i) a shift from single targets within the signalling cascade to multiple targets; (ii) a shift from therapy with a single drug to combination therapy; and (iii) investigating drugs in current clinical use for novel antiplatelet properties.     

Discovery and development of selective PPARγ modulators as safe and effective antidiabetic agents

Importance of the field: PPARγ full agonists (pioglitazone and rosiglitazone) are the mainstay drugs for the treatment of type 2 diabetes; however, mechanism-based side effects have limited their full therapeutic potential. In recent years, much progress has been achieved in the discovery and development of selective PPARγ modulators (SPPARγMs) as safer alternatives to PPARγ full agonists.

Areas covered in this review: This review focuses on the preclinical and clinical data of all the SPPARγMs discovered so far, retrieved by searching PubMed, Prous Integrity database and company news updates from 1999 to date.

What the reader will gain: Here we thoroughly discuss SPPARγMs' mode of action, briefly examine new ways to identify superior SPPARγMs, and finally, compare and contrast the pharmacological and safety profile of various agents.

Take home message: The preclinical and clinical findings clearly suggest that selective PPARγ modulators have the potential to become the next generation of PPARγ agonists: effective insulin sensitizers with a superior safety profile to that of PPARγ full agonists.     

Nootropic action of some antihypertensive drugs: computer predicting and experimental testing

Several antihypertensive drugs belonging to the group of ACE inhibitors have been selected for testing their nootropic activity based on a computer-aided prediction of their biological activity spectra using the PASS computer program package. Experiments were conducted on mice by the spontaneous orientation test (patrolling behavior) in a cross-maze. It was found that perindopril at a dose of 1 mg/kg in addition to quinapril and monopril at a dose of 10 mg/kg improved the patrolling behavior in the cross-maze test. This effect is similar to the effects of the standard nootropic drugs piracetam and meclofenoxate (at doses of 300 and 120 mg/kg, respectively). The observed nootropic effect of some ACE inhibitors is likely to be unrelated to their antihypertensive effect since the nootropic action took place only at relatively low doses of perindopril, quinapril, and monopril and was not observed with further increase of the dose. The identification of nootropic action of antihypertensive drugs that are commonly used in clinical practice leads to their new clinical applications with allowance for the relevant idiosyncrasies of patients.     

Mechanisms of action and targets for actual and future antiplatelet drugs

Platelets are key players in arterial thrombosis and have become important targets in the primary and secondary prevention of atherothrombosis. Antiplatelet drugs are primarily directed against platelets and inhibit platelet activation by a number of different mechanisms. They are used for the prevention and treatment of thrombotic processes, especially in the arterial vascular system. Antiplatelet drugs in clinical use and experimental drugs are discussed.     

Validation of observed differences in the utilization of antihypertensive and antidiabetic drugs in Northern Ireland,Norway and Sweden

Summary The amount of antihypertensive and antidiabetic drugs based of defined daily doses per 1000 inhabitants per day varies two to three fold between Northern Ireland, Norway, and Sweden. We explored whether variations based on the universally applied defined daily doses might be accounted for by national differences in the actual average prescribed daily doses. Use of prescribed daily doses for antihypertensive drugs resulted in Northern Irish and Norwegian consumption figures which were respectively 40 and 21% lower than the Swedish one, compared to 38 and 25% when defined daily doses were used. The effect of population age-sex differences on the gross defined daily doses per 1000 inhabitants per day figures was determined by applying the Northern Irish or Norwegian age-sex group proportions to Swedish age-sex specific sales data. Taking population differences into account would have resulted in antihypertensive drug use being 21 rather than 38% less in Northern Ireland and 18 rather than 25% less in Norway. Also adjustment for prescribed daily doses left an unexplained difference of 23% between Sweden and Northern Ireland and 14% between Sweden and Norway. For oral antidiabetics use of prescribed daily doses resulted in a Northern Irish — Swedish difference of 62% compared to 67% when defined daily doses were used. Simultaneous adjustment for population differences and prescribed to defined daily dose variations left a 52% difference.     

Pharmacological investigation of bezafibrate, a hypolipidemic agent (2). Mechanism of the hypolipidemic action of bezafibrate in rats

The mechanism of the hypolipidemic action of bezafibrate was investigated in rats. Bezafibrate decreased the incorporation of 14C-acetic acid into the liver and serum triglyceride and inhibited liver acetyl CoA carboxylate activity. Bezafibrate increased liver beta-oxidation, but it had no effect on lipolysis and triglyceride secretion from the liver. Bezafibrate accelerated the elimination of serum triglyceride in Intralipid injected rats and increased tissue lipoprotein lipase activity. Bezafibrate decreased the incorporation of 14C-acetic acid into liver cholesterol and inhibited liver HMG-CoA reductase activity. Bezafibrate had no effect on cholesterol absorption and excretion. These results suggest that the hypotriglyceridemic actions of bezafibrate are due to inhibition of triglyceride synthesis and acceleration of triglyceride elimination and that the hypocholesterolemic action of bezafibrate is mainly due to inhibition of liver HMG-CoA reductase activity.     

Investigational drugs for the treatment of acute myocardial infarction: focus on antiplatelet and anticoagulant agents

Background: Advances in our understanding of the complex pathophysiologic mechanisms responsible for high-risk atherosclerotic plaque rupture resulting in acute myocardial infarction (AMI) have led to the development of numerous antiplatelet and anticoagulant agents for treatment of AMI.

Areas covered: We review various antithrombotic drugs which were recently investigated for the treatment of AMI. A MEDLINE search for relevant articles on newer antiplatelet agents and anticoagulants drugs for the treatment of AMI was performed, and important original investigations were reviewed. We also briefly discuss agents that completed evaluation and were recently recommended by expert guidelines.

Expert opinion: The antiplatelet agents cangrelor and vorapaxar and the anticoagulant rivaroxaban, have shown promise for the reduction of ischemic events when administered during, and in the acute phase following AMI. However, these agents have not been compared with more potent P2Y₁₂ inhibitors, prasugrel, and ticagrelor. Finding an optimum combination of these agents to achieve an appropriate risk (bleeding) – benefit (reduction in ischemic events) balance is challenging. Further evaluation of agents that show promise is important for enhancing our armamentarium of pharmacologic agents for the successful treatment of AMI.     

Chemotherapy of mycobacterial infections: molecular action of established drugs and investigational agents

Infections caused by mycobacteria constitute important global health problems. During the last 50 years a number of drugs have achieved an established role in the therapy of these infections. These drugs, which are often used in combination, comprise both broad-spectrum agents that display antibacterial activity against mycobacteria and other organisms and narrow-spectrum agents whose activity is primarily restricted to mycobacteria, or even to individual mycobacterial species. In addition to the established agents, a number of investigational agents with antimycobacterial activity are at various stages in the research and development process. Several of the newer agents have arisen from the need to develop new drugs to combat the problems of emerging resistance to established agents. The mechanisms of action of the established drugs and investigational agents are reviewed in this update.     

New approach in the research of analgesics and antihypertensive agents]

The activation or interruption of the responses induced by regulatory peptides are ensured by ectoenzymes, the most important of them belonging to the group of zinc metallopeptidases. Thus angiotensin converting enzyme (ACE) forms the hypertensive peptide angiotensin II from its inactive precursor AI. This also the case for aminopeptidase N (APN) and neutral endopeptidase 24.11 (NEP, CALLA) which together inactivate the endogenous opioid peptides, enkephalins, whereas only NEP is involved in the metabolism of the atrial natriuretic factor (ANP) at the kidney and vascular levels. The pharmacological effects resulting from the inhibition of these enzymatic processes will appear only in tissues where the peptide substrate is tonically or phasically released. This promising approach is expected to avoid, or at least to minimize, the side effects resulting from excessive and ubiquitous stimulation of peptide receptors by exogenously administered agonists or antagonists. The essential amino acids known to be present in the active site of the bacterial endopeptidase thermolysin from crystallographic studies, have also been found in NEP by using a new program of sequence comparison associated with mutagenesis experiments. Several classes of selective inhibitors of NEP, APN and ACE have been rationally designed by taking into account the structural differences in the active site of these peptidases. Thus, the retro-inversion of the amide bond of the NEP inhibitor thiorphan resulted in the elimination of a residual interaction with ACE. Moreover, we have proposed to associate inhibitory potencies towards two peptidases in the same compound. Thus kelatorphan HONH-CO-CH2-CH(CH2 phi)-CONH-CH(CH3)-COOH and other systemically-active mixed NEP/APN inhibitors were shown capable of completely blocking enkephalin metabolism in vivo. This concept has been extended to mixed NEP/ACE inhibitors with compounds such as HS-CH2-CH(CH2 phi)-CONH-CH(CH2R)-COOH where R = CH-(CH3)2 (ES 34) or -OCH2 phi (ES 37). Only mixed inhibitors of NEP and APN are able to produce potent analgesia after intracerebroventricular or systemic administration without the major side effects of morphine (tolerance and dependence). Thiorphan or its prodrugs acetorphan or sinorphan lead to a increase in natriuresis and diuresis by protection of ANP degradation, but without any significant antihypertensive effect. Contrastingly mixed NEP/ACE inhibitors such as ES34 induce decreases in blood pressure higher than those that produced by the association of selective NEP and ACE inhibitors.     

Influence of metabolic activation on the induction of micronuclei by antihypertensive drugs in L929 cells

The influence of metabolic activation on the genotoxic activity of the antihypertensive drugs hydralazine and dihydralazine was investigated. An in vitro micronucleus test for estimating the genotoxic activity of these drugs was used. The results obtained indicated that hydralazine and dihydralazine induce micronuclei formation in L929 cells. When L929 cell cultures were treated with drugs together with liver membrane fraction (S9 fraction) from polychlorinated biphenyl (Aroclor 1254) induced rat liver, the number of micronucleated cells decrease, however, almost to the level found in control cultures. The experiments with modified S9 mix allow the conclusion that the antioxidant enzymes catalase and superoxide dismutase present in S9 liver fraction play a role in the protection of cells from the genotoxic action of hydralazine and dihydralazine.     

Transdermal delivery of antidiabetic drugs: formulation and delivery strategies

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Comparative consumption of antidiabetic drugs in britain,france and germany

Summary With the aid of IMS, a database of drug sales statistics, the quantities (expressed in Defined Daily Doses per 1000 inhabitants and per day) of antidiabetic drugs prescribed from 1978 to 1987, in Britain, France and the Federal Republik of Germany have been compared.     

Inhibition of TNF-alpha-induced RANTES expression in human hepatocyte-derived cells by fibrates,the hypolipidemic drugs

Increased concentrations and activity of plasma cytokines produced by monocytes, macrophages, and hepatocytes in patients with alcoholic liver diseases, correlate with the clinical course of liver diseases and are of prognostic value. Especially, high levels of circulating tumor necrosis factor (TNF)-alpha have been found to correlate with increased mortality in alcoholic hepatitis. Moreover, hepatic RANTES was increased in patients with alcoholic hepatitis. Thus, TNF-alpha-induced RANTES expression may have a critical role in cell-mediated liver injury associated with alcoholic hepatitis. Fibrates are widely used in the treatment of hyperlipidemia and lower triglyceride levels in patients with hyperlipidemia. Recently, several groups reported that bezafibrate, one of fibrates, is effective in primary biliary cirrhosis treatment. Additionally, it is reported that bezafibrate is effective in the treatment not only of primary biliary cirrhosis but also of chronic hepatitis C and tamoxifen-induced non-alcoholic steatohepatitis. We, here, presented that bezafibrate and fenofibrate repressed TNF-alpha-induced protein production and mRNA expression of RANTES in human hepatocyte-derived cells. Luciferase assay showed that bezafibrate and fenofibrate inhibited RANTES gene expression in response to TNF-alpha. Moreover, bezafibrate repressed TNF-alpha-induced DNA-binding activity of NF-kappaB. Thus, fibrates reduced TNF-alpha-induced NF-kappaB activation and RANTES expression, possibly suggesting that fibrates might be inhibitory agents of migration of inflammatory cells by RANTES to the liver in patients with alcoholic liver diseases. In line of these results, it might be possible that fibrates are therapeutic agents in alcoholic liver diseases.