Troglitazone-induced fulminant hepatic failure. Acute Liver Failure Study Group

Selective targeting of IRAK1 attenuates low molecular weight hyaluronic acid-induced stemness and non-canonical STAT3 activation in epithelial ovarian cancer

Advanced epithelial ovarian cancer (EOC) survival rates are dishearteningly low, with ~25% surviving beyond 5 years. Evidence suggests that cancer stem cells contribute to acquired chemoresistance and tumor recurrence. Here, we show that IRAK1 is upregulated in EOC tissues, and enhanced expression correlates with poorer overall survival. Moreover, low molecular weight hyaluronic acid, which is abundant in malignant ascites from patients with advanced EOC, induced IRAK1 phosphorylation leading to STAT3 activation and enhanced spheroid formation. Knockdown of IRAK1 impaired tumor growth in peritoneal disease models, and impaired HA-induced spheroid growth and STAT3 phosphorylation. Finally, we determined that TCS2210, a known inducer of neuronal differentiation in mesenchymal stem cells, is a selective inhibitor of IRAK1. TCS2210 significantly inhibited EOC growth in vitro and in vivo both as monotherapy, and in combination with cisplatin. Collectively, these data demonstrate IRAK1 as a druggable target for EOC.

Mechanistic Understanding of Idiosyncratic Drug-Induced Hepatotoxicity Using Co-Cultures of Hepatocytes and Macrophages

Hepatotoxicity or drug-induced liver injury (DILI) is a major safety issue in drug development as a primary reason for drug failure in clinical trials and the main cause for post-marketing regulatory measures like drug withdrawal. Idiosyncratic DILI (iDILI) is a patient-specific, multifactorial, and multicellular process that cannot be recapitulated in current in vitro models; thus, our major goal is to develop and fully characterize a co-culture system and to evaluate its suitability for predicting iDILI. For this purpose, we used human hepatoma HepG2 cells and macrophages differentiated from a monocyte cell line (THP-1) and established the appropriate co-culture conditions for mimicking an inflammatory environment. Then, mono-cultures and co-cultures were treated with model iDILI compounds (trovafloxacin, troglitazone) and their parent non-iDILI compounds (levofloxacin, rosiglitazone), and the effects on viability and the mechanisms implicated (i.e., oxidative stress induction) were analyzed. Our results show that co-culture systems including hepatocytes (HepG2) and other cell types (THP-1-derived macrophages) help to enhance the mechanistic understanding of iDILI, providing better hepatotoxicity predictions.

Engineering-inspired approaches to study β-cell function and diabetes

Strategies to mitigate the pathologies from diabetes range from simply administering insulin to prescribing complex drug/biologic regimens combined with lifestyle changes. There is a substantial effort to better understand β-cell physiology during diabetes pathogenesis as a means to develop improved therapies. The convergence of multiple fields ranging from developmental biology to microfluidic engineering has led to the development of new experimental systems to better study complex aspects of diabetes and β-cell biology. Here we discuss the available insulin-secreting cell types used in research, ranging from primary human β-cells, to cell lines, to pluripotent stem cell-derived β-like cells. Each of these sources possess inherent strengths and weaknesses pertinent to specific applications, especially in the context of engineered platforms. We then outline how insulin-expressing cells have been used in engineered platforms and how recent advances allow for better mimicry of in vivo conditions. Chief among these conditions are β-cell interactions with other endocrine organs. This facet is beginning to be thoroughly addressed by the organ-on-a-chip community, but holds enormous potential in the development of novel diabetes therapeutics. Furthermore, high throughput strategies focused on studying β-cell biology, improving β-cell differentiation, or proliferation have led to enormous contributions in the field and will no doubt be instrumental in bringing new diabetes therapeutics to the clinic.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

Gene Expression Analysis of Troglitazone Reveals Its Impact on Multiple Pathways in Cell Culture: A Case for In Vitro Platforms Combined with Gene Expression Analysis for Early (Idiosyncratic) Toxicity Screening

Peroxisome proliferator-activated receptor gamma (PPAR γ) agonists of the thiazolidinedione family are used for the treatment of type 2 diabetes mellitus due to their ability to reduce glucose and lipid levels in patients with this disease. Three thiazolidinediones that were approved for treatment are Rezulin (troglitazone), Avandia (rosiglitazone), and Actos (pioglitazone). Troglitazone was withdrawn from the market due to idiosyncratic drug toxicity. Rosiglitazone and pioglitazone are still on the market for the treatment of type 2 diabetes. The authors present data from a gene expression screen that compares the impact these three compounds have in rats, in rat hepatocytes, and in the clone 9 rat liver cell line. The authors monitored the changes in expression in multiple genes, including those related to xenobiotic metabolism, proliferation, DNA damage, oxidative stress, apoptosis, and inflammation. Compared to the other two compounds, troglitazone had a significant impact on many of the pathways monitored in vitro although no major perturbation was detected in vivo. The changes detected predict not only general toxicity but potential mechanisms of toxicity. Based on gene expression analysis, the authors propose there is not just one but multiple ways troglitazone could be toxic, depending on a patient’s environment and genetic makeup, including immune response-related toxicity.

Idiosyncratic Drug-Induced Liver Injury: Is Drug-Cytokine Interaction the Linchpin?

Idiosyncratic drug-induced liver injury continues to be a human health problem in part because drugs that cause these reactions are not identified in current preclinical testing and because progress in prevention is hampered by incomplete knowledge of mechanisms that underlie these adverse responses. Several hypotheses involving adaptive immune responses, inflammatory stress, inability to adapt to stress, and multiple, concurrent factors have been proposed. Yet much remains unknown about how drugs interact with the liver to effect death of hepatocytes. Evidence supporting hypotheses implicating adaptive or innate immune responses in afflicted patients has begun to emerge and is bolstered by results obtained in experimental animal models and in vitro systems. A commonality in adaptive and innate immunity is the production of cytokines, including interferon-γ (IFNγ). IFNγ initiates cell signaling pathways that culminate in cell death or inhibition of proliferative repair. Tumor necrosis factor-α, another cytokine prominent in immune responses, can also promote cell death. Furthermore, tumor necrosis factor-α interacts with IFNγ, leading to enhanced cellular responses to each cytokine. In this short review, we propose that the interaction of drugs with these cytokines contributes to idiosyncratic drug-induced liver injury, and mechanisms by which this could occur are discussed.

New telmisartan-derived PPARγ agonists: Impact of the 3D-binding mode on the pharmacological profile

In previous studies, the 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid was identified as pharmacophoric core for PPARγ activation. In this structure-activity relationship study the C2-alkyl chain was elongated and the 2-COOH group was changed to a carbamide/carbonitrile or shifted to the 3- or 4-position. Furthermore, the benzo[d]imidazole was exchanged by 2,3-dihydrobenzo[d]thiazole or 1H-indole. C2-propyl derivatives showed the profile of partial agonists, while elongation of the C2-chain to that of an n-heptyl group or a 4-COOH shift changed the pharmacological profile to that of a potent full agonist. This finding can be explained by binding to the LBD in different ligand conformations. Two anchoring points (Tyr473 and Arg288) exist in the LBD, which have to be contacted to achieve receptor activation. In a crystal violet chemosensitivity assay using COS-7 cells and LNCaP cells expressing PPARγ only the carbamide derivatives influenced the cell growth, independently on the presence of the PPARγ. Therefore, receptor mediated cytotoxicity can be excluded.

Pancreatic regulation of glucose homeostasis

In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed.

Profiling cumulative proportional reporting ratios of drug-induced liver injury in the FDA Adverse Event Reporting System (FAERS) database

BACKGROUND

Early prediction and accurate characterization of risk for serious liver injury associated with newly marketed drugs remains an important challenge for clinicians, the pharmaceutical industry, and regulators. To date, a biomarker that specifically indicates exposure to a drug as the etiologic cause of liver injury has not been identified.

OBJECTIVES

Using cumulative proportional reporting ratios (PRRs), we investigated 'real-time' profiles of a set of pharmaceuticals, over the first 3 years of US marketing, for the signaling of clinically serious drug-induced liver injury (DILI) in a large spontaneous-reporting database.

METHODS

Using report counts of hepatic failure or clinically serious liver injury obtained from the FDA Adverse Events Reporting System (FAERS) database, PRRs of adverse drug event terms were calculated by division of counts of domestic reports of these events by counts of all serious adverse events for each of 13 selected drugs associated with a broad range of hepatotoxic risk (including three linked to only rare instances of clinically apparent liver injury) with reference to all other drugs in the database. Drug-specific cumulative PRRs were measured at successive intervals (calendar quarters) using cumulative tallies of FAERS reports to generate time-based profiles over the initial 3 years of US marketing.

RESULTS

In the set of drugs analyzed, those with no known hepatotoxic risk demonstrated time-based cumulative PRR profiles that approximate the background rates of hepatic failure and serious liver injury reported in the entire FAERS database. In contrast, those that were removed from marketing or subjected to marketing restrictions due to their potential to cause liver injury were associated with profiles of rapidly rising cumulative PRRs that were greater than 5 within the first 10 million domestic prescriptions or the first four quarters of US marketing. The systematic tracking and identification of rising PRRs for DILI associated with newly marketed pharmaceutical and biological agents is a valuable tool for identification of safety signals within the FAERS database.

LIMITATIONS

Disproportionality profiling of spontaneous reports in FAERS (e.g., cumulative PRR measurements), which signals an association between a recently marketed drug and liver injury, is not a method to quantitatively measure drug-related risk. Regulatory actions in response to emerging drug safety concerns often depend on an accurate assessment of risks using multiple sources of data and the consideration of overall benefits and risks of the agent. Causality must be determined through analysis of individual cases to exclude other etiologies of liver injury.

CONCLUSION

The FAERS database can be used to advance empiric hepatotoxicity time-trending reporting levels for newly marketed agents in order to rapidly identify recently launched potential hepatotoxic agents and initiate further evaluation.

Natural product agonists of peroxisome proliferator-activated receptor gamma (PPARγ): a review

Agonists of the nuclear receptor PPARγ are therapeutically used to combat hyperglycaemia associated with the metabolic syndrome and type 2 diabetes. In spite of being effective in normalization of blood glucose levels, the currently used PPARγ agonists from the thiazolidinedione type have serious side effects, making the discovery of novel ligands highly relevant.

Natural products have proven historically to be a promising pool of structures for drug discovery, and a significant research effort has recently been undertaken to explore the PPARγ-activating potential of a wide range of natural products originating from traditionally used medicinal plants or dietary sources. The majority of identified compounds are selective PPARγ modulators (SPPARMs), transactivating the expression of PPARγ-dependent reporter genes as partial agonists. Those natural PPARγ ligands have different binding modes to the receptor in comparison to the full thiazolidinedione agonists, and on some occasions activate in addition PPARα (e.g. genistein, biochanin A, sargaquinoic acid, sargahydroquinoic acid, resveratrol, amorphastilbol) or the PPARγ-dimer partner retinoid X receptor (RXR; e.g. the neolignans magnolol and honokiol). A number of in vivo studies suggest that some of the natural product activators of PPARγ (e.g. honokiol, amorfrutin 1, amorfrutin B, amorphastilbol) improve metabolic parameters in diabetic animal models, partly with reduced side effects in comparison to full thiazolidinedione agonists. The bioactivity pattern as well as the dietary use of several of the identified active compounds and plant extracts warrants future research regarding their therapeutic potential and the possibility to modulate PPARγ activation by dietary interventions or food supplements.

Characterization of telmisartan-derived PPARγ agonists: importance of moiety shift from position 6 to 5 on potency, efficacy and cofactor recruitment

Selective modulation of the peroxisome proliferator-activated receptor gamma (PPARγ) by direct binding of small molecules demonstrates a promising tool for treatment of insulin resistance and type 2 diabetes mellitus. Besides its blood pressure-lowering properties, the AT1-receptor blocker telmisartan has been shown to be a partial agonist of PPARγ with beneficial metabolic effects in vitro and in mice. In our previous work, comprehensive structure-activity relationship (SAR) studies discussed the different parts of the telmisartan structure and various moieties. Based on these findings, we designed and synthesized new PPARγ ligands with a benzimidazole (agonists 4-5 and 4-6), benzothiophene (agonists 5-5 and 5-6) or benzofuran (agonists 6-5 and 6-6) moiety either at position 5 or 6 of the benzimidazole core structure. Lipophilicity and EC50 values were improved for all new compounds compared with telmisartan. Regarding PPARγ activation, the compounds were characterized by a differentiation assay using 3T3-L1 cells and a luciferase assay with COS-7 cells transiently transfected with pGal4-hPPARgDEF, pGal5-TK-pGL3 and pRL-CMV. A decrease in both potency and efficacy was observed after the shift of either the benzothiophene or the benzofuran moiety from position 6 to position 5. Selective recruitment of the coactivators TRAP220, SRC-1 and PGC-1α, and release of corepressor NCoR1 determined by time-resolved fluorescence resonance energy transfer (TR-FRET) was detected depending on residues in position 5 or 6.

Glucose-lowering drugs in patients with chronic kidney disease: a narrative review on pharmacokinetic properties

The achievement of a good glycaemic control is one of the cornerstones for preventing and delaying progression of microvascular and macrovascular complications in patients with both diabetes and chronic kidney disease (CKD). As for other drugs, the presence of an impaired renal function may significantly affect pharmacokinetics of the majority of glucose-lowering agents, thus exposing diabetic CKD patients to a higher risk of side effects, mainly hypoglycaemic episodes. As a consequence, a reduction in dosing and/or frequency of administration is necessary to keep a satisfactory efficacy/safety profile. In this review, we aim to summarize the pharmacology of the most widely used glucose-lowering agents, discuss whether and how it is altered by a reduced renal function, and the recommendations that can be made for their use in patients with different degrees of CKD.

Effects of thiazolidinediones on polycystic ovary syndrome: a meta-analysis of randomized placebo-controlled trials

INTRODUCTION

Thiazolidinedione (TZD) is one of the therapy options for polycystic ovary syndrome (PCOS) patients; however, the effectiveness of TZD in the treatment of PCOS remains controversial. The aim of this metaanalysis was to clarify the role that TZDs play in the treatment of PCOS.

METHODS

The authors searched the following databases for any date up to June 2012 for randomized controlled trials on PCOS treatment in which interventions for the experimental and control groups were TZDs and placebo, respectively: Medline, Embase, and the Cochrane library.

RESULTS

The search strategy identified 173 potential publications, eight of which were included. In the treatment of PCOS, the insulin-lowering effects of TZDs were superior to placebo (95% CI -1.50 to -0.12; P=0.021), and the lowering of fasting blood glucose was superior to placebo (95% CI -1.06 to -0.05; P=0.031). There was no difference in reduction of the Ferriman-Gallwey scores or the androgen levels between TZDs and placebo (95% CI -0.57 to 0.10; P=0.169 and 95% CI -0.64 to 0.09; P=0.141, respectively). The effects of TZDs on body weight reduction were inferior to placebo (95% CI 0.13 to 0.66; P=0.003). Significant between-study heterogeneity was detected for several variables assessed.

CONCLUSION

This is the first meta-analysis to evaluate the role that TZDs plays in the treatment of PCOS compared with placebo. The currently available data showed that TZDs can effectively reduce insulin and fasting blood glucose levels in patients with PCOS, but TZDs may not effectively reduce the Ferriman-Gallwey score or androgen levels and may increase body weight.

Efficacy of liver transplantation for acute hepatic failure: a single-center experience

BACKGROUND

Acute hepatic failure (AHF) is a devastating clinical syndrome with a high mortality rate. The outcome of AHF varies with etiology, but liver transplantation (LT) can significantly improve the prognosis and survival rate of such patients. This study aimed to detect the role of LT and artificial liver support systems (ALSS) for AHF patients and to analyze the etiology and outcome of patients with this disease.

METHODS

A retrospective analysis was made of 48 consecutive patients with AHF who fulfilled the Kings College Criteria for LT at our center. We analyzed and compared the etiology, outcome, prognosis, and survival rates of patients between the transplantation (LT) group and the non-transplantation (N-LT) group.

RESULTS

AHF was due to viral hepatitis in 25 patients (52.1%; hepatitis B virus in 22), drug or toxic reactions in 14 (29.2%; acetaminophen in 6), Wilson disease in 4 (8.3%), unknown reasons in 3 (6.3%), and miscellaneous conditions in 2 (4.2%). In the LT group, 36 patients (7 underwent living donor LT, and 29 cadaveric LT) had an average model for end-stage liver disease score (MELD) of 35.7. Twenty-eight patients survived with good graft function after a follow-up of 27.3+/-4.5 months. During the waiting time, 6 patients were treated with ALSS and 2 of them died during hospitalization. The 30-day, 12-month, and 18-month survival rates were 77.8%, 72.2%, and 66.7%, respectively. In the N-LT group, 12 patients had an average MELD score of 34.5. Four patients were treated with ALSS and all died during hospitalization. The 90-day and 1-year survival rates were only 16.7% and 8.3%, respectively.

CONCLUSIONS

Hepatitis is the most prominent cause of AHF at our center. Most patients with AHF, who fulfill the Kings College Criteria for LT, did not survive longer without LT. ALSS did not improve the prognosis of AHF patients, but may extend the waiting time for a donor. Currently, LT is still the most effective way to improve the prognosis of AHF patients.

Clinical applications of drug desensitization in the Asia-Pacific region

Drug desensitization is the induction, within hours to days, of a temporary state of tolerance to a drug which the patient has developed a hypersensitivity reaction to. It may be used for IgE and non-IgE mediated allergic reactions, and certain non-allergic reactions. The indication for desensitization is where no alternative medications are available for the treatment of that condition, and where the benefits of desensitization outweigh the risks. Desensitization is a therapeutic modality for drug allergy (similar to allergen specific immunotherapy for allergic rhinitis and insect venom anaphylaxis). In contrast, the drug provocation test is a diagnostic modality used to confirm or refute the diagnosis of drug allergy. This review discusses the clinical applications of desensitization for the treatment of common infectious, metabolic and cardiovascular diseases, and oncological conditions in the Asia-Pacific region.

Idiosyncratic drug-induced liver injury and the role of inflammatory stress with an emphasis on an animal model of trovafloxacin hepatotoxicity

Idiosyncratic adverse drug reactions (IADRs) occur in a minority of patients yet account for the majority of postmarketing use restrictions by the Food and Drug Administration. Despite the impact of these toxicities, the underlying mechanisms are still poorly understood. Animal models of IADRs would be beneficial in understanding mechanisms and in developing assays with predictive potential. Recent work exploring the interactions between inflammatory stress and drugs associated with human idiosyncratic drug-induced liver injury (IDILI) has led to the development of the first animal models that apply to a range of drugs. Here, we discuss hypotheses for the mechanisms of IDILI and focus on a murine model of trovafloxacin-induced hepatotoxicity as an example related to the inflammatory stress hypothesis.

Important elements for the diagnosis of drug-induced liver injury

BACKGROUND & AIMS

Drug-induced liver disease is the leading cause of acute liver failure in the United States. Accurate reporting of drug-induced liver injury is essential for early detection of hepatotoxicity and for developing reliable, interpretable literature. We assessed the extent to which published case reports of drug-induced liver disease include sufficient clinical data for interpreting the cause of toxicity.

METHODS

We developed a list of 42 predetermined, specific minimal elements necessary in evaluating causality of drug-induced liver injury. We then analyzed 97 published case reports or series studies of hepatotoxicity from 6 drugs (from 3 classes): amoxicillin/clavulanic acid (n = 35), troglitazone (n = 32), rosiglitazone (n = 10), pioglitazone (n = 8), zafirlukast (n = 8), and montelukast (n = 4).

RESULTS

Patient age, sex, primary disease, and drug name were reported in most, if not all, published case reports. However, many elements were underreported; some publications did not mention initial bilirubin levels (12%), many did not provide initial alkaline phosphatase levels (58%), and others provided vague descriptions of how certain diagnoses were excluded, that is, tests for hepatitis A, B, and C were negative. Data on abnormal results from serial liver tests frequently were absent. Exclusions of competing viral etiologies were reported in less than 50% of the studies.

CONCLUSIONS

Reports of drug-induced liver diseases often do not provide the data needed to determine the causes of the adverse effects. Efforts to promote and include a list of essential diagnostic elements in research articles could increase the quality and clinical utility of published case reports of drug toxicity.

Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models

Adverse drug reactions (ADRs) present a serious human health problem. They are major contributors to hospitalization and mortality throughout the world (Lazarou et al., 1998; Pirmohamed et al., 2004). A small fraction (less than 5%) of ADRs can be classified as "idiosyncratic." Idiosyncratic ADRs (IADRs) are caused by drugs with diverse pharmacological effects and occur at various times during drug therapy. Although IADRs affect a number of organs, liver toxicity occurs frequently and is the primary focus of this review. Because of the inconsistency of clinical data and the lack of experimental animal models, how IADRs arise is largely undefined. Generation of toxic drug metabolites and induction of specific immunity are frequently cited as causes of IADRs, but definitive evidence supporting either mechanism is lacking for most drugs. Among the more recent hypotheses for causation of IADRs is that inflammatory stress induced by exogenous or endogenous inflammagens is a susceptibility factor. In this review, we give a brief overview of idiosyncratic hepatotoxicity and the inflammatory response induced by bacterial lipopolysaccharide. We discuss the inflammatory stress hypothesis and use as examples two drugs that have caused IADRs in human patients: ranitidine and diclofenac. The review focuses on experimental animal models that support the inflammatory stress hypothesis and on the mechanisms of hepatotoxic response in these models. The need for design of epidemiological studies and the potential for implementation of inflammation interaction studies in preclinical toxicity screening are also discussed briefly.

How safe is the use of thiazolidinediones in clinical practice?

BACKGROUND

Thiazolidinediones (TZDs) are widely used antidiabetic drugs with proven efficacy regarding mainly surrogate markers of diabetes management. However, efficacy on surrogate markers may not always translate into benefits in clinical outcomes. Thiazolidinediones are usually well tolerated; however, their use may be associated with several adverse effects. The first TZD, troglitazone, was withdrawn from the market owing to serious hepatotoxicity. However, this does not seem to be the case with newer TZDs.

OBJECTIVE

The aim of the present review is to discuss the safety profile of this drug class.

METHODS

We searched PubMed up to July 2008 using relevant keywords.

CONCLUSIONS

Common side effects associated with TZDs include edema, weight gain, macular edema and heart failure. Moreover, they may cause hypoglycemia when combined with other antidiabetic drugs as well as decrease hematocrit and hemoglobin levels. Increased bone fracture risk is another TZD-related side effect. Thiazolidinediones tend to increase serum low density lipoprotein cholesterol levels, with rosiglitazone having a more pronounced effect compared with pioglitazone. Moreover, rosiglitazone increases low density lipoprotein particle concentration in contrast to pioglitazone where a decrease is observed. Rosiglitazone has been associated with an increase in myocardial infarction incidence. On the other hand, pioglitazone may reduce cardiovascular events. Overall, TZDs are valuable drugs for diabetes management but physicians should keep in mind that they are associated with several adverse events, the most prominent of which is heart failure.

A liquid chromatography/tandem mass spectrometry method for detecting UGT-mediated bioactivation of drugs as their N-acetylcysteine adducts in human liver microsomes

The detection of the reactive metabolites of drugs has recently been gaining increasing importance. In vitro trapping studies using trapping agents such as glutathione are usually conducted for the detection of reactive metabolites, especially those of cytochrome P450-mediated metabolism. In order to detect the UDP-glucuronosyltransferase (UGT)-mediated bioactivation of drugs, an in vitro trapping method using N-acetylcysteine (NAC) as a trapping agent followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed in this study. After the test compounds (diclofenac and ketoprofen) had been incubated in human liver microsomes with uridine diphosphoglucuronic acid (UDPGA) and NAC, the NAC adducts formed through their acyl glucuronides were analyzed using LC/MS/MS with electrospray ionization (ESI). The NAC adduct showed a mass shift of 145 units as compared to its parent, and the characteristic ion fragmentations reflected the parent. This is a concise and high-throughput method for evaluating reactive metabolites by UGT-mediated bioactivation.

The prince and the pauper. A tale of anticancer targeted agents

Cancer rates are set to increase at an alarming rate, from 10 million new cases globally in 2000 to 15 million in 2020. Regarding the pharmacological treatment of cancer, we currently are in the interphase of two treatment eras. The so-called pregenomic therapy which names the traditional cancer drugs, mainly cytotoxic drug types, and post-genomic era-type drugs referring to rationally-based designed. Although there are successful examples of this newer drug discovery approach, most target-specific agents only provide small gains in symptom control and/or survival, whereas others have consistently failed in the clinical testing. There is however, a characteristic shared by these agents: -their high cost-. This is expected as drug discovery and development is generally carried out within the commercial rather than the academic realm. Given the extraordinarily high therapeutic drug discovery-associated costs and risks, it is highly unlikely that any single public-sector research group will see a novel chemical "probe" become a "drug". An alternative drug development strategy is the exploitation of established drugs that have already been approved for treatment of non-cancerous diseases and whose cancer target has already been discovered. This strategy is also denominated drug repositioning, drug repurposing, or indication switch. Although traditionally development of these drugs was unlikely to be pursued by Big Pharma due to their limited commercial value, biopharmaceutical companies attempting to increase productivity at present are pursuing drug repositioning. More and more companies are scanning the existing pharmacopoeia for repositioning candidates, and the number of repositioning success stories is increasing. Here we provide noteworthy examples of known drugs whose potential anticancer activities have been highlighted, to encourage further research on these known drugs as a means to foster their translation into clinical trials utilizing the more limited public-sector resources. If these drug types eventually result in being effective, it follows that they could be much more affordable for patients with cancer; therefore, their contribution in terms of reducing cancer mortality at the global level would be greater.

Can in vitro metabolism-dependent covalent binding data in liver microsomes distinguish hepatotoxic from nonhepatotoxic drugs? An analysis of 18 drugs with consideration of intrinsic clearance and daily dose

In vitro covalent binding assessments of drugs have been useful in providing retrospective insights into the association between drug metabolism and a resulting toxicological response. On the basis of these studies, it has been advocated that in vitro covalent binding to liver microsomal proteins in the presence and the absence of NADPH be used routinely to screen drug candidates. However, the utility of this approach in predicting toxicities of drug candidates accurately remains an unanswered question. Importantly, the years of research that have been invested in understanding metabolic bioactivation and covalent binding and its potential role in toxicity have focused only on those compounds that demonstrate toxicity. Investigations have not frequently queried whether in vitro covalent binding could be observed with drugs with good safety records. Eighteen drugs (nine hepatotoxins and nine nonhepatotoxins in humans) were assessed for in vitro covalent binding in NADPH-supplemented human liver microsomes. Of the two sets of nine drugs, seven in each set were shown to undergo some degree of covalent binding. Among hepatotoxic drugs, acetaminophen, carbamazepine, diclofenac, indomethacin, nefazodone, sudoxicam, and tienilic acid demonstrated covalent binding, while benoxaprofen and felbamate did not. Of the nonhepatotoxic drugs evaluated, buspirone, diphenhydramine, meloxicam, paroxetine, propranolol, raloxifene, and simvastatin demonstrated covalent binding, while ibuprofen and theophylline did not. A quantitative comparison of covalent binding in vitro intrinsic clearance did not separate the two groups of compounds, and in fact, paroxetine, a nonhepatotoxin, showed the greatest amount of covalent binding in microsomes. Including factors such as the fraction of total metabolism comprised by covalent binding and the total daily dose of each drug improved the discrimination between hepatotoxic and nontoxic drugs based on in vitro covalent binding data; however, the approach still would falsely identify some agents as potentially hepatotoxic.

Idiosyncratic drug reactions: past, present, and future

Although the major working hypothesis for the mechanism of idiosyncratic drug reactions (IDRs), the hapten hypothesis, has not changed since 1987, several hypotheses have been added, for example, the danger hypothesis and the pharmaceutical interaction hypothesis. Genetic studies have found that several IDRs are linked to specific HLA genes, providing additional evidence that they are immune-mediated. Evidence that most IDRs are caused by reactive metabolites has led pharmaceutical companies to avoid drug candidates that form significant amounts of reactive metabolites; however, at least one IDR, ximelagatran-induced liver toxicity, does not appear to be caused by a reactive metabolite. It is possible that there are biomarkers such as those related to cell stress that would predict that a drug candidate would cause a significant incidence of IDRs; however, there has been no systematic study of the changes in gene expression induced by drugs known to cause IDRs. A major impediment to the study of the mechanisms of IDRs is the paucity of valid animal models, and if we had a better mechanistic understanding, it should be easier to develop such models. There is growing evidence that these adverse reactions are more varied and complex than previously recognized, and it is unlikely that a quick fix will be achieved. However, IDRs are an important cause of patient morbidity and mortality and markedly increase the uncertainty of drug development; therefore, continued basic research in this area is essential.

Mechanisms and outcomes of drug- and toxicant-induced liver toxicity in diabetes

Increase dincidences of hepatotoxicity have been observed in diabetic patients receiving drug therapies. Neither the mechanisms nor the predisposing factors underlying hepatotoxicity in diabetics are clearly understood. Animal studies designed to examine the mechanisms of diabetes-modulated hepatotoxicity have traditionally focused only on bioactivation/detoxification of drugs and toxicants. It is becoming clear that once injury is initiated, additional events determine the final outcome of liver injury. Foremost among them are two leading mechanisms: first, biochemical mechanisms that lead to progression or regression of injury; and second, whether or not timely and adequate liver tissue repair occurs to mitigate injury and restore liver function. The liver has a remarkable ability to repair and restore its structure and function after physical or chemical-induced damage. The dynamic interaction between biotransformation-based liver injury and compensatory tissue repair plays a pivotal role in determining the ultimate outcome of hepatotoxicity initiated by drugs or toxicants. In this review, mechanisms underlying altered hepatotoxicity in diabetes with emphasis on both altered bioactivation and liver tissue repair are discussed. Animal models of both marked sensitivity (diabetic rats) and equally marked protection (diabetic mice) from drug-induced hepatotoxicity are described. These examples represent a remarkable species difference. Availability of the rodent diabetic models offers a unique opportunity to uncover mechanisms of clinical interest in averting human diabetic sensitivity to drug-induced hepatotoxicities. While the rat diabetic models appear to be suitable, the diabetic mouse models might not be suitable in preclinical testing for potential hepatotoxic effects of drugs or toxicants, because regardless of type 1 or type2 diabetes, mice are resistant to acute drug-or toxicant-induced toxicities.

Idiosyncratic toxicity: a convergence of risk factors

The therapeutic margin for any drug is based on both toxicity and efficacy. Generally, toxicity is dose-dependent and is driven either by the therapeutic target or by an untoward target. However, idiosyncratic toxicities are usually not observed until a drug has been on the market and has gained broad exposure. Except in the case of pharmacokinetic interactions, these toxicities are not driven solely by drug exposure but rather depend on several drug- and patient-related risk factors. Drug-related risk factors include metabolism, bioactivation and covalent binding, and the inhibition of key cell functions. Patient-related risk factors include underlying disease, age, gender, comedications, nutritional status, activation of the innate immune system, physical activity, and genetic predispositions. Idiosyncratic toxicity can occur when a convergence of risk factors, including drug exposure, tips the risk-benefit balance away from benefit and toward risk.

Oral antidiabetic agents as cardiovascular drugs

The increased risk of cardiovascular disease associated with type 2 diabetes is well documented. Lesser degrees of abnormal glucose metabolism including impaired fasting glycaemia and impaired glucose tolerance are also associated with increased cardiovascular risk. Studies showing improved cardiovascular outcomes with oral antidiabetic agents are limited, with the UKPDS demonstrating improved macrovascular outcomes only in a subgroup of obese patients with type 2 diabetes treated with metformin, and the heavily criticized STOP NIDDM trial showing a reduction in the number of cardiovascular events with the alpha glucosidase inhibitor acarbose. In recent years there has been an increase in the number of oral antidiabetic drugs available to treat the hyperglycaemia of diabetes. Some of these drugs have complex metabolic properties, additional to their antihyperglycaemic effect, improving endothelial function and markers of atherogenesis, with the potential to reduce cardiovascular morbidity and mortality, as supported by the recently published results of the PROACTIVE study. The results of further long-term cardiovascular outcome studies with these newer agents are awaited.

The obesity epidemic and its cardiovascular consequences

PURPOSE OF REVIEW

Obesity has reached global epidemic proportions because of an increasingly obesogenic environment. This review examines the association between obesity, and in particular visceral fat, as a risk factor for cardiovascular disease and mortality.

RECENT FINDINGS

The World Health Organization defines obesity based on the body mass index. Recently the waist-to-hip ratio has been shown to be a significantly stronger predictor of cardiovascular events than body mass index. The metabolic syndrome and its evolving definition represent a cluster of metabolic risk factors which help predict cardiovascular disease and mortality. Although insulin resistance plays a central role in the pathophysiology of the metabolic syndrome, there is limited support for therapy with insulin sensitizers, thiazolidinediones, in patients with coronary artery disease. The current anti-obesity drugs, orlistat and sibutramine, have only a modest effect on weight loss. The blockade of the endocannabinoid system with rimonabant, however, may be a promising new strategy.

SUMMARY

Obesity is associated with significant increase in cardiovascular risk. Lifestyle modification remains the cornerstone of management although anti-obesity medications may be indicated in high risk individuals with comorbid disease.

Thiazolidinediones in patients with diabetes mellitus and heart failure : implications of emerging data

Individuals with diabetes mellitus have an increased risk of developing heart failure, usually as a consequence of coronary artery disease, although a specific diabetic cardiomyopathy, secondary to a microangiopathy, may also exist. The thiazolidinediones, a relatively new class of insulin-sensitizing agents used in the management of type 2 diabetes mellitus, have a number of complex metabolic actions on surrogate markers of atherogenesis, supported by the results of the recently published PROACTIVE (PROspective pioglitAzone Clinical Trial In macroVascular Events) trial. Unfortunately, the use of thiazolidinediones in individuals with diabetes mellitus and heart failure is limited because of a propensity to cause fluid retention. The underlying mechanisms of fluid retention have yet to be fully elucidated, but appear to be a dose-related class effect, exacerbated by combination therapy with insulin, and in some cases may be localized to peripheral edema. In parallel, echocardiographic studies show no significant effect of thiazolidinediones on cardiac structure or function. The design of epidemiologic studies describing an increased risk of developing heart failure in individuals with type 2 diabetes mellitus prescribed thiazolidinediones has been questioned, and a study of 'new users' of antihyperglycemic treatments found no increased risk of hospitalization for heart failure with thiazolidinedione therapy. There is also increasing evidence for the potential benefits of insulin sensitization in patients with diabetes mellitus and known heart failure, and a large observational study of over 16 000 patients with a principal discharge diagnosis of heart failure found a reduced mortality (hazard ratio [HR] 0.87; 95% CI 0.80, 0.94) in those prescribed thiazolidinediones. This benefit was offset by an increased risk of readmission with heart failure (HR 1.06; 95% CI 1.00, 1.09). Despite an increase in fluid-related events, recent studies suggest that individuals with type 2 diabetes mellitus and heart failure (New York Heart Association grade I/II) can be treated with thiazolidinediones with appropriate monitoring and adjustment of heart failure therapies. These findings would suggest the need for large-scale, prospective trials to investigate the safety and potential benefits of thiazolidinedione use in patients with diabetes mellitus and heart failure.

Combination therapy using metformin or thiazolidinediones and insulin in the treatment of diabetes mellitus

The biguanide, metformin, sensitizes the liver to the effect of insulin, suppressing hepatic glucose output. Thiazolidinediones such as rosiglitazone and pioglitazone enhance insulin-mediated glucose disposal, leading to reduced plasma insulin concentrations. These classes of drugs may also have varying beneficial effects on features of insulin resistance such as lipid levels, blood pressure and body weight. Metformin in combination with insulin has been shown to significantly improve blood glucose levels while lowering total daily insulin dose and body weight. The thiazolidinediones in combination with insulin have also been effective in lowering blood glucose levels and total daily insulin dose. Triple combination therapy using insulin, metformin and a thiazolidinedione improves glycaemic control to a greater degree than dual therapy using insulin and metformin or insulin and a thiazolidinedione. There is insufficient evidence to recommend the use of metformin or thiazolidinediones in type 1 diabetic patients. Although these agents are largely well tolerated, some subjects experience significant gastrointestinal problems while using metformin. Metformin is associated with a low risk of lactic acidosis, but should not be used in patients with elevated serum creatinine or those being treated for congestive heart failure. The thiazolidinediones are associated with an increase in body weight, although this can be avoided with careful lifestyle management. Thiazolidinediones may also lead to oedema and are associated with a low incidence of hepatocellular injury. Thiazolidinediones are contraindicated in patients with underlying heart disease who are at risk of congestive heart failure and in patients who have abnormal hepatic function. The desired blood glucose-lowering effect and adverse event profiles of these agents should be considered when recommending these agents to diabetic patients. The potential for metformin or the thiazolidinediones to impact long-term cardiovascular outcomes remains under investigation.

Recognizing drug-induced liver injury: current problems, possible solutions

Currently there are three major problems in understanding drug-induced liver injury (DILI): (1) reliably establishing whether the liver disease was caused by the drug, or by another process; (2) determining the true incidence of and clinical risk factors for drug-induced hepatotoxicity; and(3) elaborating the mechanisms by which injury occurs to hepatocytes and other liver cells. We have focused here on the first two problems, as issues that may be amenable to actions in the near future, but the third may take substantially longer to work out. The first problem requires sufficient information for medical differential diagnosis. There are no pathognomonic indicators of DILI; even liver biopsy is not diagnostic. Making the correct attribution of causality requires analyzing the temporal relationship of drug exposure to illness and excluding all other possible causes. The second problem, determining incidence, cannot be done entirely adequately using currently available methods, whether by clinical trials, by spontaneous adverse event reports, or by retrospective epidemiologic studies. There is need for prospective safety studies to establish the true incidence of DILI caused by a drug, to identify risk factors for it, and to collect biologic materials for analytic studies toward better understanding mechanisms of DILI.

Role of insulin secretagogues and insulin sensitizing agents in the prevention of cardiovascular disease in patients who have diabetes

In the absence of clinical trial evidence to compare the secretagogues with sensitizers, it is difficult to make recommendations about which class of drug is more important to prescribe for the prevention of cardiovascular disease in diabetes mellitus. Epidemiologic data supports insulin resistance as a major factor in cardiovascular disease through a variety of mechanisms. Because sensitizers improve insulin sensitivity and correct many of the vascular abnormalities that are associated with insulin resistance, it is tempting to suggest that they may be superior for this purpose. Conversely, meeting the goals that are recommended for glycemia also are important and achieving them may not be always possible with sensitizers, particularly in the later stages of the disease when insulin levels are not high,despite insulin resistance. In such situations,combination therapy may be needed with both types of drugs. No data are available on the cardiovascular effects of such combinations;some retrospective data suggest a possibility of increased events with the combination of sulfonylureas and metformin. Thus, further prospective studies in this area are necessary.

Comparison of pioglitazone with other antidiabetic drugs for associated incidence of liver failure: no evidence of increased risk of liver failure with pioglitazone

AIM

The aim of this study was to assess the incidence of liver failure in association with antidiabetic treatment using pioglitazone vs. other oral antidiabetic medications.

METHODS

The study was a retrospective analysis of claim data from the PharMetrics Patient-Centric Database that had over 1.12 million enrollees with type 2 diabetes. All patients, > or =18 years of age with type 2 diabetes, who had initiated treatment either with a thiazolidinedione (pioglitazone and rosiglitazone), sulfonylurea or metformin were identified and matched on the basis of propensity scores, which served as a proxy for severity of disease. The primary measure of interest was the incidence of liver failure or hepatitis post-index date. In addition to unadjusted comparisons, Cox proportional hazard models were employed to estimate the risk of developing liver failure or hepatitis.

RESULTS

There was no significant difference in the 1- and 2-year incidence rates of liver failure or hepatitis (primary and secondary diagnoses) between the pioglitazone monotherapy group and the respective comparator groups. In Cox proportional hazard models controlling for age, pre-index total healthcare costs, Charlson comorbidity index, procedures and a hospitalization or Emergency room (ER) visit for pre-index hyperglycaemia, and pioglitazone were not associated with an increased risk of liver failure or hepatitis, compared to all other defined groups. Furthermore, no primary or secondary diagnosis of liver failure was reported in the pioglitazone group during the follow-up period.

CONCLUSIONS

Results of retrospective data analysis demonstrate no evidence of increased risk of liver failure or hepatitis for patients initiating therapy on pioglitazone, compared to other oral antidiabetic agents. Pioglitazone therapy was not associated with an increased risk of liver failure at 2 years relative to other oral antidiabetic therapies.

The stepwise approach to the management of type 2 diabetes

As the prevalence of type 2 diabetes continues to increase worldwide, there is an enhanced need for effective disease management. Type 2 diabetes is managed through a stepwise program of intensive therapy that consists of lifestyle modifications and sequential addition of oral antihyperglycemic agents and insulin as necessary. Successful implementation of this approach lessens the microvascular complications of the disease and promotes a lifestyle that may reduce macrovascular complications and comorbidities. Because of the progressive pancreatic beta-cell failure that causes hyperglycemia in type 2 diabetes, many people with type 2 diabetes will ultimately require insulin for disease management. Insulin may be used alone or in combination with oral agents to achieve glycemic control with a minimum of side effects. Although disease management regimens must be tailored to the needs of the individual with type 2 diabetes, the health care provider should always employ an aggressive, treat-to-target strategy to lower hyperglycemia and lessen diabetes-related risk factors.

Inflammation and drug idiosyncrasy--is there a connection?

"Drug idiosyncrasy" refers to untoward reactions to drugs that occur in a small fraction of patients and have no obvious relationship to dose or duration of therapy. The liver is a frequent target for toxicity. Much of the conventional thinking about mechanisms of drug idiosyncrasy has centered on hypotheses that the reactions have a metabolic basis involving drug metabolism polymorphisms or that they arise from a specific immune response to the drug or its metabolite(s). For very few drugs does convincing evidence exist for either of these mechanisms, however. The erratic temporal and dose relationships that characterize idiosyncratic drug responses suggest the possibility that some event during the course of therapy renders tissues peculiarly susceptible to toxic effects of the drug. For example, episodes of inflammation are commonplace in people, and results of numerous studies in animals indicate that a modest inflammatory response can enhance tissue sensitivity to a variety of toxic chemicals. These observations have led to the hypothesis that an episode of inflammation during drug therapy could decrease the threshold for drug toxicity and thereby render an individual susceptible to a toxic reaction that would not otherwise occur (i.e., an "idiosyncratic" response). This hypothesis can explain the features of drug idiosyncrasy using fundamental pharmacologic principles, and results of recent animal studies are supportive of this. Knowledge gaps that need to be filled before the hypothesis should be widely accepted are discussed.

Drug therapy of diabetes in the elderly

The prevalence of type 2 diabetes mellitus is increasing in the elderly. Although type 1 diabetic patients are living longer, over 95% of elderly people affected with diabetes have type 2 diabetes. This segment of the population, comprising men and women older than 65 years of age, is more likely to develop coexisting illnesses predisposing to the development of diabetes and complicating its management. In addition to changes in lifestyle, inherent age-related changes in carbohydrate metabolism contribute to the development of type 2 diabetes in old age. The long-term outcome of tight blood sugar control in the elderly is not known. Nevertheless the principles of management of type 2 diabetes in the elderly are essentially the same as in young- or middle-aged diabetic patients. Lifestyle modifications remain the cornerstone of medical therapy. When diet and exercise fail to achieve proper glycemic control, oral pharmacologic therapy and/or insulin therapy is indicated. The recently available oral glucose lowering agents in the market along with the newer types of insulin can be used in elderly diabetic patients. The effect of aging on metabolism and drug elimination kinetics must, however, be taken into consideration. In particular, it should be borne in mind that the risk of hypoglycemia is more deleterious in the elderly and should be avoided. In this review, the various pharmacologic agents available for the management of diabetes will be reviewed and some pertinent clinical guidelines will be suggested.

Leukotriene antagonists

Hepatotoxicity is the most common cause of fulminant hepatic failure in the United States and the main indication for market withdrawal of drugs. This condition has been increasingly recognized as a problem of enormous medical, financial legal, and regulatory importance. It is in context of this heightened awareness of hepatotoxicity, particularly associated with new high profile drugs, that the authors reviews the published data regarding liver injury related to a novel group of asthma drugs.

Hepatotoxicity of the thiazolidinediones

Troglitazone, the first of the thiazolidinediones, caused severe hepatotoxicity including liver failure in several patients. It appears, however, that the thiazolidinediones as a class are not as hepatotoxic as troglitazone. Comparative data at comparable dates of usage indicate that pioglitazone and rosiglitazone are not significant hepatotoxins. This is further supported by experimental data that demonstrate that troglitazone, alone among the thiazolidinediones, is toxic in hepatocyte cell culture. All of the thiazolidinediones cause ALT elevations; however, ALT monitoring for hepatotoxicity does not appear to prevent serious liver disease nor reduce patient risk.

The starch from Solanum lycocarpum St. Hill. fruit is not a hypoglycemic agent

We have investigated the hypoglycemic effect induced by the starch obtained from the unripe fruits of Solanum lycocarpum (Solanaceae). Per os administration of the starch (1000 or 2000 mg/kg, twice daily for 7 days, N = 6) did not change glycemia levels of nondiabetic female Swiss mice weighing 25-30 g. In streptozotocin-induced diabetic mice, similar treatment with the starch did not change the elevated glycemia 3 h after the last dose (diabetic treated with saline = 288 17/309 18; starch 1000 mg/kg = 295 +/- 33; starch 2000 mg/kg = 258 +/- 37; N = 5). In animals fasted for 15 h, per os administration of glucose (600 mg/kg) significantly increased glycemia 1 h later. Previous (-30 min) treatment of the animals with the starch (1000 or 2000 mg/kg; N = 5) did not change the increase of glycemia. Per os administration of the starch (1000 or 2000 mg kg-1 day-1, twice daily for 7 days) did not induce body weight gain or loss. The chemical analysis of the starch indicated the presence of glycoalkaloids, a finding that represents a reason for concern since many of these substances are generally toxic. In interviews with 56 diabetic patients, 29 medicinal plants were reported as useful in their treatment of diabetes and S. lycocarpum was the sixth most frequently mentioned. All patients interviewed reported that they also used insulin or oral hypoglycemic drugs. The results of the present study do not provide evidence for a hypoglycemic effect associated with the polysaccharide fraction of S. lycocarpum in either normal or hyperglycemic mice. These data demonstrate the need for adequate pharmacological investigation of the natural products widely used in folk medicine.

Insulin sensitizers

Type 2 diabetes mellitus is an increasingly prevalent disorder associated with multiple metabolic derangements. Insulin resistance is the most prominent feature common in both type 2 diabetes and its associated metabolic abnormalities. Until 1995, the only therapeutic interventions available in the United States were the insulin secretagogues sulfonylureas and insulin. With the introduction of metformin in the United States in the mid-1990s and the subsequent advent of thiazolidinediones, an opportunity exists to address and directly reverse, at least in part, the defects in insulin action seen in individuals with type 2 diabetes. Evidence shows that insulin sensitizers not only have beneficial effects on glycemic control but also have multiple effects on lipid metabolism and atherosclerotic vascular processes that could prove to be beneficial. We discuss safety issues of these agents, their potential use in preventing onset and progression of diabetes, and their use in other related metabolic conditions such as polycystic ovary syndrome.

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