Hepatotoxicity with thiazolidinediones: is it a class effect?

Unraveling the mechanisms of hepatogenous diabetes and its therapeutic perspectives

The review focused mainly on the pathogenesis of hepatogenous diabetes (HD) in liver cirrhosis (LC). This review reveals parallels between the mechanisms of metabolic dysfunction observed in LC and type II diabetes (T2DM), suggesting a shared pathway leading to HD. It underscores the role of insulin in HD pathogenesis, highlighting key factors such as insulin signaling, glucose metabolism, insulin resistance (IR), and the influence of adipocytes. Furthermore, the impact of adipose tissue accumulation, fatty acid metabolism, and pro-inflammatory cytokines like Tumor necrosis factor-α (TNF-α) on IR are discussed in the context of HD. Altered signaling pathways, disruptions in the endocrine system, liver inflammation, changes in muscle mass and composition, and modifications to the gut microbiota collectively contribute to the complex interplay linking cirrhosis and HD. This study highlights how important it is to identify and treat this complex condition in cirrhotic patients by thoroughly analyzing the link between cirrhosis, IR, and HD. It also emphasizes the vitality of targeted interventions. Cellular and molecular investigations into IR have revealed potential therapeutic targets for managing and preventing HD.

Harnessing peroxisome proliferator-activated receptor γ agonists to induce Heme Oxygenase-1: a promising approach for pulmonary inflammatory disorders

The activation of peroxisome proliferator-activated receptor (PPAR)-γ has been extensively shown to attenuate inflammatory responses in conditions such as asthma, acute lung injury, and acute respiratory distress syndrome, as demonstrated in animal studies. However, the precise molecular mechanisms underlying these inhibitory effects remain largely unknown. The upregulation of heme oxygenase-1 (HO-1) has been shown to confer protective effects, including antioxidant, antiapoptotic, and immunomodulatory effects in vitro and in vivo. PPARγ is highly expressed not only in adipose tissues but also in various other tissues, including the pulmonary system. Thiazolidinediones (TZDs) are highly selective agonists for PPARγ and are used as antihyperglycemic medications. These observations suggest that PPARγ agonists could modulate metabolism and inflammation. Several studies have indicated that PPARγ agonists may serve as potential therapeutic candidates in inflammation-related diseases by upregulating HO-1, which in turn modulates inflammatory responses. In the respiratory system, exposure to external insults triggers the expression of inflammatory molecules, such as cytokines, chemokines, adhesion molecules, matrix metalloproteinases, and reactive oxygen species, leading to the development of pulmonary inflammatory diseases. Previous studies have demonstrated that the upregulation of HO-1 protects tissues and cells from external insults, indicating that the induction of HO-1 by PPARγ agonists could exert protective effects by inhibiting inflammatory signaling pathways and attenuating the development of pulmonary inflammatory diseases. However, the mechanisms underlying TZD-induced HO-1 expression are not well understood. This review aimed to elucidate the molecular mechanisms through which PPARγ agonists induce the expression of HO-1 and explore how they protect against inflammatory and oxidative responses.

Pharmacokinetic, toxicological, and clinical considerations for the treatment of type 2 diabetes in patients with liver disease: a comprehensive update

INTRODUCTION

Type 2 diabetes and liver disease, mainly metabolic-associated fatty liver disease (MAFLD) and more rarely cirrhosis, coexist in many patients. This duality has direct implications for the physician when choosing glucose-lowering agents, with classical concerns but also recent new hopes.

AREAS COVERED

This updated comprehensive review will consider the pharmacokinetics, the tolerance/safety profile, the benefit/risk balance in cirrhosis, the effects on MAFLD and the risk of hepatocellular carcinoma of old and new glucose-lowering compounds in patients with liver disease, with a special focus on glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors.

EXPERT OPINION

We are currently facing a new paradigm in the management of patients with diabetes and liver disease. From previous reluctance when using antidiabetic agents (except insulin) in diabetic patients with hepatic impairment because of safety concerns, the commercialization of novel glucose-lowering agents has changed the scene. These agents, which have a good safety profile, are associated with weight loss and pleiotropic effects. They have proven their efficacy in improving MAFLD. However, more specific studies are still needed to prove their efficacy in preventing the progression to fibrosis/cirrhosis and confirm this new opportunity for the management of patients with diabetes and liver disease.

Clinical pharmacology of antidiabetic drugs: What can be expected of their use?

The pharmacotherapy of type 2 diabetes mellitus (T2DM) has markedly evolved in the last two decades. Classical antidiabetic agents (sulphonylureas, metformin, insulin) are now in competition with new glucose-lowering medications. Alpha-glucosidase inhibitors and thiazolidinediones (glitazones) were not able to replace older agents, because of insufficient efficacy and/or poor tolerability/safety. In contrast, incretin-based therapies, both dipeptidyl peptidase-4 inhibitors (DPP-4is or gliptins, oral agents) and glucagon-like peptide-1 receptor agonists (GLP-1RAs, subcutaneous injections) are a major breakthrough in the management of T2DM. Because they are not associated with hypoglycaemia and weight gain, DPP-4is tend to replace sulphonylureas as add-on to metformin while GLP-1RAs tend to replace basal insulin therapy after failure of oral therapies. Furthermore, placebo-controlled cardiovascular outcome trials demonstrated neutrality for DPP-4is, but cardiovascular protection for GLP-1RAs in patients with T2DM at high cardiovascular risk. More recently sodium-glucose cotransporter 2 inhibitors (SGLT2is or gliflozins, oral agents) also showed cardiovascular protection, especially a reduction in hospitalization for heart failure, as well as a renal protection in patients with and without T2DM, at high cardiovascular risk, with established heart failure and/or with chronic kidney disease. Thus, GLP-1RAs and SGLT2is are now considered as preferred drugs in T2DM patients with or at high risk of atherosclerotic cardiovascular disease whereas SGLT2is are more specifically recommended in patients with or at risk of heart failure and renal (albuminuric) disease. The management of T2DM is moving from a glucocentric approach to a broader strategy focusing on all risk factors, including overweight/obesity, and to an organ-disease targeted personalized approach.

An Approach to the Management of Diabetes Mellitus in Cirrhosis: A Primer for the Hepatologist

The management of diabetes in cirrhosis and liver transplantation can be challenging. There is difficulty in diagnosis and monitoring of diabetes as fasting blood sugar values are low and glycosylated hemoglobin may not be a reliable marker. The challenges in the management of diabetes in cirrhosis include the likelihood of cognitive impairment, risk of hypoglycemia, altered drug metabolism, frequent renal dysfunction, risk of lactic acidosis, and associated malnutrition and sarcopenia. Moreover, calorie restriction and an attempt to lose weight in obese diabetics may be associated with a worsening of sarcopenia. Many commonly used antidiabetic drugs may be unsafe or be associated with a high risk of hypoglycemia in cirrhotics. Post-transplant diabetes is common and may be contributed by immunosuppressive medication. There is inadequate clinical data on the use of antidiabetic drugs in cirrhosis, and the management of diabetes in cirrhosis is hampered by the lack of guidelines focusing on this issue. The current review aims at addressing the practical management of diabetes by a hepatologist.

Therapeutic potentials of agonist and antagonist of adenosine receptors in type 2 diabetes

Type 2 diabetes has been a global health challenge over the decades and is among the leading causes of death. Several treatment approaches have been developed, but more effective and new therapies are still needed. The role of adenosine in glucose and lipid homeostasis has offered a different therapeutic approach. Adenosine mediates its physiological role through the activation of adenosine receptors. These adenosine receptors have been implicated in glucose and lipid homeostasis. The ability of agonists and antagonists of adenosine receptors to activate or inhibit the adenosine signalling cascade and thereby affecting the balance of glucose and lipid homeostasis has challenged the studies of agonists and antagonists of adenosine receptors, both preclinical and clinical, as potential anti-diabetic drugs. This review provides a background on different anti-diabetic therapeutic approaches, outlining the role of adenosine receptors in glucose and lipid homeostasis, and mechanisms underlying the action of agonists/antagonists of adenosine receptors as a therapeutic potential towards type 2 diabetes.

Discovery of Atabecestat (JNJ-54861911): A Thiazine-Based β-Amyloid Precursor Protein Cleaving Enzyme 1 Inhibitor Advanced to the Phase 2b/3 EARLY Clinical Trial

Accumulation of amyloid β peptides (Aβ) is thought to be one of the causal factors of Alzheimer's disease (AD). The aspartyl protease β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate-limiting protease for Aβ production, and therefore, BACE1 inhibition is a promising therapeutic approach for the treatment of AD. Starting with a dihydro-1,3-thiazine-based lead, Compound J, we discovered atabecestat 1 (JNJ-54861911) as a centrally efficacious BACE1 inhibitor that was advanced into the EARLY Phase 2b/3 clinical trial for the treatment of preclinical AD patients. Compound 1 demonstrated robust and dose-dependent Aβ reduction and showed sufficient safety margins in preclinical models. The potential of reactive metabolite formation was evaluated in a covalent binding study to assess its irreversible binding to human hepatocytes. Unfortunately, the EARLY trial was discontinued due to significant elevation of liver enzymes, and subsequent analysis of the clinical outcomes showed dose-related cognitive worsening.

Metabolic Comorbidities and Risk of Development and Severity of Drug-Induced Liver Injury

The incidence and rates of diagnosis of drug-induced liver injury (DILI) have been increasing in recent years as findings from basic research and the examination of clinical databases reveal information about the clinical course, etiology, and prognosis of this complex disease. The prevalence of metabolic comorbidities (e.g., diabetes mellitus, fatty liver, obesity, and metabolic syndrome (MetS)) has been increasing during the same period. The results of preclinical and clinical research studies indicate that characteristics of metabolic comorbidities are also factors that affect DILI phenotype and progression. The objective of this review is to present the evidence for DILI and hepatotoxicity mechanisms, incidence, and outcomes in patients with MetS and nonalcoholic fatty liver disease. Moreover, we also summarize the relationships between drugs used to treat metabolic comorbidities and DILI.

Effective Therapeutic Delivery and Bioavailability Enhancement of Pioglitazone Using Drug in Adhesive Transdermal Patch

The administration of pioglitazone as an oral therapy is restricted due to various challenges. The aim of the current investigation was to evaluate the suitability of pioglitazone in adhesive transdermal patch as an alternative delivery system, in order to improve therapeutic delivery. Drug in adhesive pioglitazone (2% w/w) transdermal patch were optimized for drug release, suitable adhesive, and skin permeation enhancer. The selected patch was examined for drug-loading capacity and the patch with greater pioglitazone (6% w/w) was evaluated in rat models. The release of pioglitazone was influenced by the tested adhesive and was shown to be significantly higher (p < 0.001) with patch, prepared using Duro-Tak 87-2516. The ex vivo permeation results substantiate the release data as a greater transdermal flux (15.67 ± 2.35 µg/cm²/h) was demonstrated in patch fabricated with Duro-Tak 87-2516. Skin penetration enhancers promoted the ex vivo transdermal delivery of pioglitazone, and was ~2 folds (p < 0.0001) higher with propylene glycol, as compared to patch without enhancer. The maximum solubility of pioglitazone in Duro-Tak 87-2516 was found to be 6% w/w. Increasing the drug content in patch enhanced the transdermal flux and was highest when the pioglitazone level was 6% w/w (72.68 ± 5.76 µg/cm²/h). In vivo pharmacokinetic data demonstrate that the AUC_0-α in transdermal application (13,506.51 ± 1649.92 ng·h/mL) was ~2 times higher (p < 0.0001) as compared to oral dosage form. In conclusion, the promising results observed here signifies that developed patch could be a viable alternative for oral therapy of pioglitazone.

Establishment of a mouse model of troglitazone-induced liver injury and analysis of its hepatotoxic mechanism

Drug-induced liver injury is a major problem in drug development and clinical drug therapy. Troglitazone (TGZ), a thiazolidinedione antidiabetic drug for the treatment of type II diabetes mellitus, was found to induce rare idiosyncratic severe liver injury in patients, which led to its withdrawal in 2000. However, in normal experimental animals in vivo TGZ has never induced liver injury. To explore TGZ hepatotoxic mechanism, we established a novel mouse model of TGZ-induced liver injury. Administration of BALB/c female mice with a single intraperitoneal TGZ dose (300 mg/kg) significantly elevated alanine aminotransferase and aspartate aminotransferase levels 6 hours after the treatment. The ratio of oxidative stress marker glutathione/disulfide glutathione was significantly decreased. The increased hepatic mRNA levels of inflammation- and oxidative stress-related factors were observed in TGZ-treated mice. Subsequently, hepatic transcriptome profiles of TGZ-exposed liver were compared with those of non-hepatotoxic rosiglitazone. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was activated in TGZ-induced liver injury. The activation of the JAK/STAT pathway promoted phosphorylation of STAT3 in TGZ-treated mice. Consequently, upregulation of STAT3 activation increased mRNA levels of its downstream genes. In conclusion, a single intraperitoneal dose of TGZ exposure could induce liver injury in BALB/c female mice and, by a hepatic transcriptomic analysis, we found that the activation of JAK/STAT pathway might be related to TGZ-induced hepatotoxicity.

Evaluating biological activity of compounds by transcription factor activity profiling

Assessing the biological activity of compounds is an essential objective of biomedical research. We show that one can infer the bioactivity of compounds by assessing the activity of transcription factors (TFs) that regulate gene expression. Using a multiplex reporter system, the FACTORIAL, we characterized cell response to a compound by a quantitative signature, the TF activity profile (TFAP). We found that perturbagens of biological pathways elicited distinct TFAP signatures in human cells. Unexpectedly, perturbagens of the same pathway all produced identical TFAPs, regardless of where or how they interfered. We found invariant TFAPs for mitochondrial, histone deacetylase, and ubiquitin/proteasome pathway inhibitors; cytoskeleton disruptors; and DNA-damaging agents. Using these invariant signatures permitted straightforward identification of compounds with specified bioactivities among uncharacterized chemicals. Furthermore, this approach allowed us to assess the multiple bioactivities of polypharmacological drugs. Thus, TF activity profiling affords straightforward assessment of the bioactivity of compounds through the identification of perturbed biological pathways.

Hepatogenous Diabetes: An Underestimated Problem of Liver Cirrhosis

The prevalence of diabetes mellitus in cirrhotic patients is much higher than that in the general population. Two types of diabetes are usually seen in patients with cirrhosis: type 2 diabetes mellitus and hepatogenous diabetes (HD). The HD is an acquired condition which is believed to be caused by impaired insulin clearance and pancreatic β-cell dysfunction in cirrhotic patients. Increased levels of advanced glycation end products and hypoxia-inducible factors have been implicated in the pathogenesis of HD. Patients with HD typically present with normal fasting glucose, but abnormal response to an oral glucose tolerance test, which is required for the diagnosis. Because the level of glycated hemoglobin is often falsely low in patients with cirrhosis, it does not help in the early diagnosis of HD. HD is associated with an increased rate of complications of cirrhosis, decreased 5-year survival rate, and increased risk of hepatocellular carcinoma. The major complications of cirrhosis associated with HD include hepatic encephalopathy (HE), spontaneous bacterial peritonitis, sepsis, variceal hemorrhage, and renal dysfunction. Treatment of HD may be difficult as many antihyperglycemic therapies are associated with increased risk of complications in cirrhosis, particularly hypoglycemia. Biguanides, alpha-glucosidase inhibitors, and new medications such as dipeptidyl peptidase-4 inhibitors and sodium-glucose co-transporter 2 inhibitors appear to be safe in patients with cirrhosis. Though insulin therapy is currently advocated, requirement of insulin is variable and is difficult to predict. The liver transplantation usually results in reversal of HD. This review article provides an overview of magnitude, patients' characteristics, clinical implications, pathophysiological mechanisms, diagnosis, and management of HD.

Inter-individual differences in the susceptibility of primary human hepatocytes towards drug-induced cholestasis are compound and time dependent

Cholestasis represents a major subtype of drug-induced liver injury and novel preclinical models for its prediction are needed. Here we used primary human hepatocytes (PHH) from different donors in 2D-sandwich (2D-sw) and/or 3D-spheroid cultures to study inter-individual differences in the response towards cholestatic hepatotoxins after short-term (48-72 hours) and long-term repeated exposures (14 days). The cholestatic liabilities of drugs were determined by comparing cell viability upon exposure to the highest non-cytotoxic drug concentration in the presence and absence of a non-cytotoxic concentrated bile acid mixture. In 2D-sw culture, cyclosporine A and amiodarone presented clear cholestatic liabilities in all four PHH donors tested, whereas differences in the susceptibility of the various PHH donors towards the cholestatic toxicity of bosentan, chlorpromazine and troglitazone were observed. In PHH from one donor, the cholestatic liabilities of chlorpromazine and troglitazone could only be detected after long-term repeated exposures when maintained in 3D-spheroid culture, but not after short-term exposures in either 2D-sw or 3D-spheroid culture, suggesting that cholestatic hepatotoxicity may require time to develop. In conclusion, inter-individual susceptibility exists towards drug-induced cholestasis, which depends on the compound as well as the exposure time.

New Pioglitazone Metabolites and Absence of Opened-Ring Metabolites in New N-Substituted Thiazolidinedione

Thiazolidinediones (TZDs) are drugs used to treat type 2 diabetes mellitus; however, several safety concerns remain regarding the available drugs in this class. Therefore, the search for new TZD candidates is ongoing; metabolism studies play a crucial step in the development of new candidates. Pioglitazone, one of the most commonly used TZDs, and GQ-11, a new N-substituted TZD, were investigated in terms of their metabolic activity in rat and human liver microsomes to assess their metabolic stability and investigate their metabolites. Methods for preparation of samples were based on liquid-liquid extraction and protein precipitation. Quantitation was performed using liquid chromatography (LC)-tandem mass spectrometry, and the metabolite investigation was performed using ultraperformance LC coupled to a hybrid quadrupole-time of flight mass spectrometer. The predicted intrinsic clearance of GQ-11 was 70.3 and 46.1 ml/kg per minute for rats and humans, respectively. The predicted intrinsic clearance of pioglitazone was 24.1 and 15.9 ml/kg per minute for rats and humans, respectively. The pioglitazone metabolite investigation revealed two unpublished metabolites (M-D and M-A). M-A is a hydration product and may be related to the mechanism of ring opening and the toxicity of pioglitazone. The metabolites of GQ-11 are products of oxidation; no ring-opening metabolite was observed for GQ-11. In conclusion, under the same experimental conditions, a ring-opening metabolite was observed only for pioglitazone. The resistance of GQ-11 to the ring opening is probably related to N-substitution in the TZD ring.

Practical Review of Oral Antihyperglycemic Agents for Type 2 Diabetes Mellitus

This article gives a practical review of the pharmacology, clinical efficacy, safety, dosing, cost, and place in therapy for oral antihyperglycemic agents used in the treatment of type 2 diabetes mellitus. There are 5 classes of oral antihyperglycemic agents available in the United States: sulfonylurea secretagogues, biguanides, α-glucosidase inhibitors, thiazolidinediones, and nonsulfonylurea secretagogues. These agents have distinct characteristics that help in their selection for the treatment of type 2 diabetes.

Drug induced mitochondrial dysfunction: Mechanisms and adverse clinical consequences

Several commonly used medications impair mitochondrial function resulting in adverse effects or toxicities. Drug induced mitochondrial dysfunction may be a consequence of increased production of reactive oxygen species, altered mitochondrial permeability transition, impaired mitochondrial respiration, mitochondrial DNA damage or inhibition of beta-oxidation of fatty acids. The clinical manifestation depends on the specific drug and its effect on mitochondria. Given the ubiquitous presence of mitochondria and its central role in cellular metabolism, drug-mitochondrial interactions may manifest clinically as hepatotoxicity, enteropathy, myelosuppression, lipodystrophy syndrome or neuropsychiatric adverse effects, to name a few. The current review focuses on specific drug groups which adversely affect mitochondria, the mechanisms involved and the clinical consequences based on the data available from experimental and clinical studies. Knowledge of these adverse drug-mitochondrial interactions may help the clinicians foresee potential issues in individual patients, prevent adverse drug reactions or alter drug regimens to enhance patient safety.

Evidence-based selection of training compounds for use in the mechanism-based integrated prediction of drug-induced liver injury in man

The current test systems employed by pharmaceutical industry are poorly predictive for drug-induced liver injury (DILI). The ‘MIP-DILI’ project addresses this situation by the development of innovative preclinical test systems which are both mechanism-based and of physiological, pharmacological and pathological relevance to DILI in humans. An iterative, tiered approach with respect to test compounds, test systems, bioanalysis and systems analysis is adopted to evaluate existing models and develop new models that can provide validated test systems with respect to the prediction of specific forms of DILI and further elucidation of mechanisms. An essential component of this effort is the choice of compound training set that will be used to inform refinement and/or development of new model systems that allow prediction based on knowledge of mechanisms, in a tiered fashion. In this review, we focus on the selection of MIP-DILI training compounds for mechanism-based evaluation of non-clinical prediction of DILI. The selected compounds address both hepatocellular and cholestatic DILI patterns in man, covering a broad range of pharmacologies and chemistries, and taking into account available data on potential DILI mechanisms (e.g. mitochondrial injury, reactive metabolites, biliary transport inhibition, and immune responses). Known mechanisms by which these compounds are believed to cause liver injury have been described, where many if not all drugs in this review appear to exhibit multiple toxicological mechanisms. Thus, the training compounds selection offered a valuable tool to profile DILI mechanisms and to interrogate existing and novel in vitro systems for the prediction of human DILI.

Oral Antidiabetic Agents: A Comparative Review

Type 2 diabetes mellitus is a chronic disease characterized by insulin resistance, impaired insulin secretion, and/or increased hepatic glucose production. The mainstays of drug treatment are the oral antidiabetic agents. Insulin is usually reserved for patients who do not achieve fasting plasma glucose or A1C goals with or cannot tolerate the oral antidiabetic agents. There are 5 classes of oral antidiabetic agents available in the United States: sulfonylureas, biguanides, alpha-glucosidase inhibitors, thiazolidinediones, and nonsulfonylurea secretagogues. They have differences and similarities with respect to their pharmacology and role in diabetes. This article reviews the pharmacology, efficacy, safety, and selection of the oral agents used to treat type 2 diabetes mellitus.

The treatment of diabetes mellitus of patients with chronic liver disease

About 80% of patients with liver cirrhosis may have glucose metabolism disorders, 30% show overt diabetes mellitus (DM). Prospective studies have demonstrated that DM is associated with an increased risk of hepatic complications and death in patients with liver cirrhosis. DM might contribute to liver damage by promoting inflammation and fibrosis through an increase in mitochondrial oxidative stress mediated by adipokines. Based on the above mentioned the effective control of hyperglycemia may have a favorable impact on the evolution of these patients. However, only few therapeutic studies have evaluated the effectiveness and safety of antidiabetic drugs and the impact of the treatment of DM on morbidity and mortality in patients with liver cirrhosis. In addition, oral hypoglycemic agents and insulin may produce hypoglycemia and lactic acidosis, as most of these agents are metabolized by the liver. This review discusses the clinical implications of DM in patients with chronic liver disease. In addition the effectiveness and safety of old, but particularly the new antidiabetic drugs will be described based on pharmacokinetic studies and chronic administration to patients. Recent reports regarding the use of the SGLT2 inhibitors as well as the new incretin-based therapies such as injectable glucagon-like peptide-1 (GLP-1) receptor agonists and oral inhibitors of dipeptidylpeptidase-4 (DPP-4) will be discussed. The establishment of clear guidelines for the management of diabetes in patients with CLD is strongly required.

Cytotoxicity of thiazolidinedione-, oxazolidinedione- and pyrrolidinedione-ring containing compounds in HepG2 cells

Liver damage occurred in some patients who took troglitazone (TGZ) for type II diabetes. The 2,4-thiazolidinedione (TZD) ring in TGZ's structure has been implicated in its hepatotoxicity. To further examine the potential role of a TZD ring in toxicity we used HepG2 cells to evaluate two series of compounds containing different cyclic imides. N-phenyl analogues comprised 3-(3,5-dichlorophenyl)-2,4-thiazolidinedione (DCPT); 3-(3,5-dichlorophenyl)-2,4-oxazolidinedione (DCPO) and N-(3,5-dichlorophenyl)succinimide (NDPS). Benzylic compounds, which closely resemble TGZ, included 5-(3,5-dichlorophenylmethyl)-2,4-thiazolidinedione (DCPMT); 5-(4-methoxyphenylmethyl)-2,4-thiazolidinedione (MPMT); 5-(4-methoxyphenylmethylene)-2,4-thiazolidinedione (MPMT-I); 5-(4-methoxyphenylmethyl)-2,4-oxazolidinedione (MPMO); 3-(4-methoxyphenylmethyl)succinimide (MPMS) and 3-(4-methoxyphenylmethylene)succinimide (MPMS-I). Cytotoxicity was assessed using the MTS assay after incubating the compounds (0-250μM) with HepG2 cells for 24h. Only certain TZD derivatives (TGZ, DCPT, DCPMT and MPMT-I) markedly decreased cell viability, whereas MPMT had low toxicity. In contrast, analogues without a TZD ring (DCPO, NDPS, MPMO, MPMS and MPMS-I) were not cytotoxic. These findings suggest that a TZD ring may be an important determinant of toxicity, although different structural features, chemical stability, cellular uptake or metabolism, etc., may also be involved. A simple clustering approach, using chemical fingerprints, assigned each compound to one of three classes (each containing one active compound and close homologues), and provided a framework for rationalizing the activity in terms of structure.

Pharmacokinetics and clinical evaluation of the alogliptin plus pioglitazone combination for type 2 diabetes

INTRODUCTION

Type 2 diabetes is a complex disease with multiple defects, which generally requires a combination of several pharmacological approaches to reach glucose control targets. A unique fixed-dose combination combines a thiazolidinedione (pioglitazone) and a dipeptidyl peptidase-4 inhibitor (alogliptin).

AREA COVERED

An extensive literature search was performed to analyze the pharmacokinetics of pioglitazone and alogliptin when used separately and in combination as well as to summarize clinical and toxicological considerations about the combined therapy.

EXPERT OPINION

Pioglitazone, a potent insulin sensitizer, and alogliptin, an incretin-based agent that potentiates post-meal insulin secretion and reduces glucagon secretion, have complementary mechanisms of action. The clinical efficacy of a combined therapy is superior to any single therapy in patients treated with diet or with metformin (with or without sulphonylurea). These two drugs can be administered once daily, with or without a meal. No clinically relevant pharmacokinetic interactions between the two agents have been described and the fixed-dose combination has shown bioequivalence with alogliptin and pioglitazone given separately. Combining alogliptin with pioglitazone does not alter the safety profile of each compound. Weight gain observed with pioglitazone may be limited with the addition of alogliptin. The concern of an increased risk of heart failure remains to be better investigated.

LPSF/GQ-02 inhibits the development of hepatic steatosis and inflammation in a mouse model of non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) defines a wide spectrum of liver diseases that extends from simple steatosis to non-alcoholic steatohepatitis. Although the pathogenesis of NAFLD remains undefined, it is recognized that insulin resistance is present in almost all patients who develop this disease. Thiazolidinediones (TZDs) act as an insulin sensitizer and have been used in the treatment of patients with type 2 diabetes and other insulin-resistant conditions, including NAFLD. Hence, therapy of NAFLD with insulin-sensitizing drugs should ideally improve the key hepatic histological changes, while also reducing cardiometabolic and cancer risks. Controversially, TZDs are associated with the development of cardiovascular events and liver problems. Therefore, there is a need for the development of new therapeutic strategies to improve liver function in patients with chronic liver diseases. The aim of the present study was to assess the therapeutic effects of LPSF/GQ-02 on the liver of LDLR-/- mice after a high-fat diet. Eighty male mice were divided into 4 groups and two different experiments: 1-received a standard diet; 2-fed with a high-fat diet (HFD); 3–HFD+pioglitazone; 4–HFD+LPSF/GQ-02. The experiments were conducted for 10 or 12 weeks and in the last two or four weeks respectively, the drugs were administered daily by gavage. The results obtained with an NAFLD murine model indicated that LPSF/GQ-02 was effective in improving the hepatic architecture, decreasing fat accumulation, reducing the amount of collagen, decreasing inflammation by reducing IL-6, iNOS, COX-2 and F4 / 80, and increasing the protein expression of IκBα, cytoplasmic NFκB-65, eNOS and IRS-1 in mice LDLR -/-. These results suggest a direct action by LPSF/GQ-02 on the factors that affect inflammation, insulin resistance and fat accumulation in the liver of these animals. Further studies are being conducted in our laboratory to investigate the possible mechanism of action of LPSF/GQ-02 on hepatic lipid metabolism.

Tolerability and pharmacokinetics of lobeglitazone, a novel peroxisome proliferator-activated receptor-γ agonist, after a single oral administration in healthy female subjects

BACKGROUND AND OBJECTIVES

Lobeglitazone is a recently approved peroxisome proliferator-activated receptor-γ agonist for the treatment of type 2 diabetes mellitus in Korea. The purpose of this study was to investigate the pharmaco kinetic properties of lobeglitazone in healthy females and to compare these with historical data in healthy males.

METHODS

This study was designed as a block-randomized, double-blind, placebo-controlled, parallel-group study. A single 2 or 4 mg oral dose of lobeglitazone or a placebo was randomly administered to 22 female subjects, and pharmacokinetic blood samples were obtained after dosing. Pharmacokinetic parameters were calculated by a non-compartmental method, and the results were compared with those previously obtained from male subjects. Tolerability was assessed by clinical and laboratory parameters.

RESULTS

During the study, a total of 28 adverse events (AEs) were observed in the lobeglitazone group (n = 16) and nine AEs in the placebo group (n = 6). Serious AEs or significant clinical changes were not observed. After oral administration, lobeglitazone was rapidly absorbed with the time to maximum plasma concentration (t(max)) ranging from 0.5 to 4.0 h. The mean (standard deviation) maximum plasma concentration (C(max)) and area under the plasma concentration-time curve from time zero to infinity (AUC(∞)) for the 2 mg dose were 214.8 (56.4) µg/L and 2,251.3 (721.2) µg·h/L, respectively, and the corresponding values for the 4 mg dose were 310.0 (47.8) µg/L and 6,942.6 (1,778.9) µg·h/L, respectively. The ratios (95 % CIs) for the geometric means (female/male) of the C(max) and AUC∞ were 1.23 (0.89-1.69) and 1.11 (0.73-1.68), respectively (2 mg), and 1.28 (1.01-1.63) and 2.36 (1.60-3.47), respectively (4 mg).

CONCLUSION

Lobeglitazone was well-tolerated in healthy females. There was no sex difference for systemic lobeglitazone exposure at a 2 mg dose; however, female subjects showed greater systemic exposure than males after the administration of 4 mg of lobeglitazone. In spite of the pharmacokinetic difference, dose adjustment based on sex alone is not needed in clinical use because therapy should be individualized for each patient to achieve glycemic control.

Prodrugs of pioglitazone for extended-release (XR) injectable formulations

N-Acyloxymethyl derivatives of pioglitazone (PIO) have been prepared and characterized as model candidates for extended-release injectable formulations. All PIO derivatives prepared are crystalline solids as determined by powder X-ray diffraction, and the solubility in aqueous media is below 1 μM at 37 °C. The melting points steadily increase from 55 °C, for the hexanoyloxymethyl derivative, to 85 °C, for the palmitoyloxymethyl derivative; inversely, the solubilities in ethyl oleate decrease as a function of increasing acyl chain length. The butyroyloxymethyl ester has a higher melting point and a lower solubility in ethyl oleate than expected from the trend. The (13)C solid-state NMR spectra of the PIO homologues between the hexanoyloxymethyl derivative and stearoyloxymethyl derivative suggest a common structural motif with the acyl chains exchanging between two distinct conformations, and the rate of exchange is slower for longer chain derivatives. The butyroyloxymethyl derivative is efficiently converted to PIO in in vitro rat plasma with a half-life of <2 min at 37 (o) C, while the rate of enzymatic cleavage in rat plasma decreases as the ester chain length increases for the longer acyloxymethyl derivatives. The concentration of PIO in plasma increases rapidly, or "spikes," in the hours following intramuscular (IM) injection of either the HCl salt or the butyroyloxymethyl derivative. In contrast, the more lipophilic palmitoyloxymethyl derivative provides slow growth in the PIO concentration over the first day to reach levels that remain steady for 2 weeks. On the basis of its in vivo pharmacokinetic profile, as well as material and solubility properties, the PIO palmitoyloxymethyl derivative has potential as a once-monthly injectable medication to treat diabetes.

Pharmacokinetic and toxicological considerations for the treatment of diabetes in patients with liver disease

INTRODUCTION

Patients with type 2 diabetes have an increased risk of chronic liver disease (CLD) such as non-alcoholic fatty liver disease and steatohepatitis and about one-third of cirrhotic patients have diabetes. However, the use of several antidiabetic agents may be a cause for concern in the case of hepatic impairment (HI).

AREAS COVERED

An extensive literature search was performed to analyze the influence of HI on the pharmacokinetics (PK) of glucose-lowering agents and the potential consequences for clinical practice as far as the efficacy/safety balance of their use in diabetic patients with CLD is concerned.

EXPERT OPINION

Almost no PK studies have been published regarding metformin, sulfonylureas, thiazolidinediones and α-glucosidase inhibitors in patients with HI. Only mild changes in PK of glinides, dipeptidyl peptidase-4 inhibitors and sodium glucose cotransporters type 2 inhibitors were observed in dedicated PK studies in patients with various degrees of HI, presumably without major clinical relevance although large clinical experience is lacking. Glucagon-like peptide-1 receptor agonists have a renal excretion rather than liver metabolism. Rare anecdotal case reports of hepatotoxicity have been described with various glucose-lowering agents contrasting with numerous reassuring data. Nevertheless, caution should be recommended, especially in patients with advanced cirrhosis, including with the use of metformin.

Peroxisome proliferator-activated receptor gamma and regulations by the ubiquitin-proteasome system in pancreatic cancer

Pancreatic cancer is one of the most lethal forms of human cancer. Although progress in oncology has improved outcomes in many forms of cancer, little progress has been made in pancreatic carcinoma and the prognosis of this malignancy remains grim. Several molecular abnormalities often present in pancreatic cancer have been defined and include mutations in K-ras, p53, p16, and DPC4 genes. Nuclear receptor Peroxisome Proliferator-Activated Receptor gamma (PPARγ) has a role in many carcinomas and has been found to be overexpressed in pancreatic cancer. It plays generally a tumor suppressor role antagonizing proteins promoting carcinogenesis such as NF-κB and TGFβ. Regulation of pathways involved in pancreatic carcinogenesis is effectuated by the Ubiquitin Proteasome System (UPS). This paper will examine PPARγ in pancreatic cancer, the regulation of this nuclear receptor by the UPS, and their relationship to other pathways important in pancreatic carcinogenesis.

Comparative molecular profiling of the PPARα/γ activator aleglitazar: PPAR selectivity, activity and interaction with cofactors

Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear hormone receptors that control the expression of genes involved in a variety of physiologic processes, through heterodimerization with retinoid X receptor and complex formation with various cofactors. Drugs or treatment regimens that combine the beneficial effects of PPARα and γ agonism present an attractive therapeutic strategy to reduce cardiovascular risk factors. Aleglitazar is a dual PPARα/γ agonist currently in phase III clinical development for the treatment of patients with type 2 diabetes mellitus who recently experienced an acute coronary event. The potency and efficacy of aleglitazar was evaluated in a head-to-head comparison with other PPARα, γ and δ ligands. A comprehensive, 12-concentration dose-response analysis using a cell-based assay showed aleglitazar to be highly potent, with EC(50) values of 5 nM and 9 nM for PPARα and PPARγ, respectively. Cofactor recruitment profiles confirmed that aleglitazar is a potent and balanced activator of PPARα and γ. The efficacy and potency of aleglitazar are discussed in relation to other dual PPARα/γ agonists, in context with the published X-ray crystal structures of both PPARα and γ.

Drug safety of rosiglitazone and pioglitazone in France: a study using the French PharmacoVigilance database

Background

Thiazolidinediones (TZDs), rosiglitazone (RGZ) and pioglitazone (PGZ) are widely used as hypoglycemic drugs in patients with type 2 diabetes mellitus. The aim of our study was to investigate the profile of adverse drug reactions (ADRs) related to TZDs and to investigate potential risk factors of these ADRs.

Methods

Type 2 diabetic patients were identified from the French Database of PharmacoVigilance (FPVD) between 2002 and 2006. We investigated ADR related to TZD, focusing on 4 ADR: edema, heart failure, myocardial infarction and hepatitis corresponding to specific WHO-ART terms.

Results

Among a total of 99,284 adult patients in the FPVD, 2295 reports concerned type 2 diabetic patients (2.3% of the whole database), with 161 (7%) exposed to TZDs. The frequency of edema and cardiac failure was significantly higher with TZDs than in other patients (18% and 7.4% versus 0.8% and 0.1% respectively, p < 0.001) whereas the frequency of hepatitis was similar (5.9% versus 4%, NS). A multiple logistic regression model taking into account potential confounding factors (age, gender, drug exposure and co-morbidities) found that TZD exposure remained associated with heart failure and edema, but not with hepatitis or myocardial infarction.

Conclusions

Thiazolidinediones exposure is associated with an increased risk of edema and heart failure in patients with type 2 diabetes even when recommendations for use are respected. In contrast, the risk of hepatic reactions and myocardial infarction with this class of drugs seems to be similar to other hypoglycemic agents.

Effect of structural modifications on 3-(3,5-dichlorophenyl)-2,4-thiazolidinedione-induced hepatotoxicity in Fischer 344 rats

Glitazones, used for type II diabetes, have been associated with liver damage in humans. A structural feature known as a 2,4-thiazolidinedione (TZD) ring may contribute to this toxicity. TZD rings are of interest since continued human exposure via the glitazones and various prototype drugs is possible. Previously, we found that 3-(3,5-dichlorophenyl)-2,4-thiazolidinedione (DCPT) was hepatotoxic in rats. To evaluate the importance of structure on DCPT toxicity, we therefore studied two series of analogs. The TZD ring was replaced with: a mercaptoacetic acid group {[[[(3,5-dichlorophenyl)amino]carbonyl]thio]acetic acid, DCTA}; a methylated TZD ring [3-(3,5-dichlorophenyl)-5-methyl-2,4-thiazolidinedione, DPMT]; and isomeric thiazolidinone rings [3-(3,5-dichlorophenyl)-2- and 3-(3,5-dichlorophenyl)-4-thiazolidinone, 2-DCTD and 4-DCTD, respectively]. The following phenyl ring-modified analogs were also tested: 3-phenyl-, 3-(4-chlorophenyl)-, 3-(3,5-dimethylphenyl)- and 3-[3,5-bis(trifluoromethyl)phenyl]-2,4-thiazolidinedione (PTZD, CPTD, DMPT and DFMPT, respectively). Toxicity was assessed in male Fischer 344 rats 24 h after administration of the compounds. In the TZD series only DPMT produced liver damage, as evidenced by elevated serum alanine aminotransferase (ALT) activities at 0.6 and 1.0 mmol kg(-1) (298.6 ± 176.1 and 327.3 ± 102.9 Sigma-Frankel units ml(-1) , respectively) vs corn oil controls (36.0 ± 11.3) and morphological changes in liver sections. Among the phenyl analogs, hepatotoxicity was observed in rats administered PTZD, CPTD and DMPT; with ALT values of 1196.2 ± 133.6, 1622.5 ± 218.5 and 2071.9 ± 217.8, respectively (1.0 mmol kg(-1) doses). Morphological examination revealed severe hepatic necrosis in these animals. Our results suggest that hepatotoxicity of these compounds is critically dependent on the presence of a TZD ring and also the phenyl substituents.

The potentially inappropriate prescription of new drug: thiazolidinediones for patients with type II diabetes in Taiwan

PURPOSE

To examine the potentially inappropriate prescription of thiazolidinediones (TZD).

METHODS

Data on TZD prescriptions were collected from Taiwan's National Health Insurance dataset from 2001 to 2006. TZDs were considered inappropriately prescribed when they were prescribed to patients who were (1) under 18 years old, (2) pregnant, who had (3) type 1 diabetes, (4) severe heart failure, (5) hepatic insufficiency, or (6) renal insufficiency and taking TZD + metformin in combination. We aggregated potentially inappropriate prescriptions of TZD for each health-care institution in each month starting from March 2001, when TZD was introduced to Taiwan's market.

RESULTS

The potentially inappropriate prescription of TZD increased from 9.41% in 2001 to 12.50% in 2006. Prior inappropriate prescription led to a 0.06% (95%CI: 0.04-0.08) further increase in its later inappropriate prescription. Accumulated months of experience prescribing TZD was found associated with higher proportion of inappropriate prescription of TZD (0.03%, 95%CI: 0.01-0.05). However, it was negatively associated with new incidence of inappropriate prescription of TZD (-0.20, 95%CI: -0.22 to -0.18). The greater the volume of prior TZD prescription (-0.87%, 95%CI: -0.93 to -0.81) and the greater the number of accumulated months since adoption (-0.14%, 95%CI: -0.16 to -0.12), the greater the decrease in rates of new inappropriate prescriptions.

CONCLUSIONS

Along with the quick penetration of the new DM drug came an increased possibility that it would be prescribed inappropriately, a trend that persisted over time.

Case series of liver failure associated with rosiglitazone and pioglitazone

PURPOSE

The thiazolidinedione drugs rosiglitazone and pioglitazone are not widely known to be hepatotoxic. We evaluated the FDA Adverse Event Reporting System (AERS) to determine the number of reported cases of liver failure associated with rosiglitazone and pioglitazone between 1997 and 2006, and described their clinical characteristics.

METHODS

Adverse event reports spontaneously submitted to the FDA AERS from 1997 to 2006 were examined. Liver failure associated with rosiglitazone or pioglitazone was defined as liver injury accompanied by hepatic encephalopathy, liver transplantation, placement on a liver transplant list, or death in which all other likely etiologies were excluded. Using prescribing data, the number of reported cases of liver failure per million patient-years of exposure was calculated for each drug.

RESULTS

Twenty-one cases met our case definition. Clinical characteristics, outcomes, and pathologic data were similar between cases of liver failure associated with rosiglitazone and with pioglitazone. The median duration of therapy was 9 weeks and 85% of cases were acute, defined as symptom onset to liver failure in less than 26 weeks. The case-fatality rate was 81% (17/21), and only 14% (3/21) spontaneously recovered. Accounting for underreporting, the number needed to harm (NNH) for each case of liver failure was 44 000 patient-years of exposure for rosiglitazone and 52 000 patient-years of exposure for pioglitazone.

CONCLUSIONS

This is the largest case series of liver failure associated with rosiglitazone or pioglitazone reported to date, strengthening the evidence that these drugs can cause severe hepatotoxicity.

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.