Thiazolidinediones and congestive heart failure: a judicious balance of risks and benefits

New Peroxisome Proliferator-Activated Receptor Agonist (GQ-11) Improves Wound Healing in Diabetic Mice

Objective: Chronic wounds associated with diabetes are an important public health problem demanding new treatments to improve wound healing and decrease amputations. Monocytes/macrophages play a key role in sustained inflammation associated with impaired healing and local administration of peroxisome proliferator-activated receptor (PPAR)γ agonists may modulate macrophage, improving healing. In this study, we investigated the effects of GQ-11, a partial/dual PPARα/γ agonist, on macrophage function and wound healing in diabetes. Approach: Wounds were surgically induced at the dorsum of C57BL/6J and BKS.Cg-Dock7^m +/+ Lepr^db/J (db/db) mice and treated with hydrogel (vehicle), pioglitazone or GQ-11, for 7 or 10 days, respectively. After treatment, wounds were analyzed histologically and by quantitative PCR (qPCR). In addition, bone marrow-derived macrophages (BMDM) were cultured from C57BL/6J mice and treated with vehicle, pioglitazone, or GQ-11, after challenge with lipopolysaccharide or interleukin-4 to be analyzed by qPCR and flow cytometry. Results: GQ-11 treatment upregulated anti-inflammatory/pro-healing factors and downregulated pro-inflammatory factors both in wounds of db/db mice and in BMDM. Innovation: Wounds of db/db mice treated with GQ-11 exhibited faster wound closure and re-epithelization, increased collagen deposition, and less Mac-3 staining compared with vehicle, providing a new approach to treatment of diabetic wound healing to prevent complications. Conclusion: GQ-11 improves wound healing in db/db mice, regulating the expression of pro- and anti-inflammatory cytokines and wound growth factors, leading to increased re-epithelization and collagen deposition.

New indole-thiazolidine attenuates atherosclerosis in LDLr(-/-) mice

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor γ (PPARγ) agonists that improve insulin-mediated glucose uptake and possess beneficial vasculoprotective actions. However, because undesirable side effects are associated with these drugs, novel TZDs are under development. In this study, we evaluated the biological activity of LYSO-7, a new indole-thiazolidine, on PPAR activation, inflammation and atherogenesis using a gene reporter assay, lipopolysaccharide (LPS)-activated RAW 264.7 cell culture, and a low-density lipoprotein receptor knockout (LDLr(-/-)) mouse model of atherosclerosis. LYSO-7 shows low cytotoxicity in RAW 264.7 cells and at 2.5μmol/L induces PPARα and PPARγ transactivation as well as inhibits LPS-induced nitrite production and the mRNA gene expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1). In addition, treatment with LYSO-7 reduces the development of atherosclerosis in LDLr(-/-) mice, improves the lipid profile, blood glucose levels, and downregulates CD40 and CD40L expression without affecting the body weight of the animals. Altogether, our data show that LYSO-7 possesses anti-inflammatory properties and that treatment with this TZD attenuates atherosclerosis progression in LDLr(-/-) mice by modulating lipid metabolism and inflammation. Thus, LYSO-7 shows potential as a new drug candidate for the treatment of atherosclerosis.

Submaximal PPARγ activation and endothelial dysfunction: new perspectives for the management of cardiovascular disorders

PPARγ activation plays an important role in glucose metabolism by enhancing insulin sensitization. PPARγ is a primary target for thiazolidinedione-structured insulin sensitizers like pioglitazone and rosiglitazone employed for the treatment of type 2 diabetes mellitus. Additionally, PPARγ activation inhibits adhesion cascades and detrimental vascular inflammatory events. Importantly, activation of PPARγ plays a distinctive role in regulating the physiology and expression of endothelial nitric oxide synthase (eNOS) in the endothelium, resulting in enhanced generation of vascular nitric oxide. The PPARγ activation-mediated vascular anti-inflammatory and direct endothelial functional regulatory actions could, therefore, be beneficial in improving the vascular function in patients with atherosclerosis and hypertension with or without diabetes mellitus. Despite the disappointing cardiac side effect profile of rosiglitazone-like PPARγ full agonists, the therapeutic potential of novel pharmacological agents targeting PPARγ submaximally cannot be ruled out. This review discusses the potential regulatory role of PPARγ on eNOS expression and activation in improving the function of vascular endothelium. We argue that partial/submaximal activation of PPARγ could be a major target for vascular endothelial functional improvement. Interestingly, newly synthesized partial agonists of PPARγ such as balaglitazone, MBX-102, MK-0533, PAR-1622, PAM-1616, KR-62776 and SPPARγM5 are devoid of or have a reduced tendency to cause the adverse effects associated with full agonists of PPARγ. We propose that the vascular protective properties of pharmacological agents, which submaximally activate PPARγ, should be investigated. Moreover, the therapeutic opportunities of agents that submaximally activate PPARγ in preventing vascular endothelial dysfunction (VED) and VED-associated cardiovascular disorders are discussed.

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.

Sitagliptin compared with thiazolidinediones as a third-line oral antihyperglycemic agent in type 2 diabetes mellitus

OBJECTIVE

To compare sitagliptin and thiazolidinediones as third-line oral antihyperglycemic agents among ethnic minority patients with poorly controlled type 2 diabetes mellitus.

METHODS

In an open-label, single-arm design, we treated type 2 diabetic patients who had suboptimal diabetes control on maximum tolerated dosages of metformin plus sulfonylureas with the addition of sitagliptin, 100 mg daily, and compared their responses with findings from a historical control group of similar patients treated with rosiglitazone, 8 mg daily, or pioglitazone, 45 mg daily, as their third-line oral agent. Patients were assessed bimonthly, and those who achieved hemoglobin A1c levels less than 7.5% at 4 months continued through 1 year of follow-up.

RESULTS

One hundred eight patients were treated with sitagliptin, and 104 patients constituted the historical control group treated with rosiglitazone or pioglitazone. At baseline, sitagliptin- and thiazolidinedione-treated patients had identical hemoglobin A1c levels (mean ± SD) (9.4 ± 1.8% and 9.4 ± 1.9%, respectively) and similar known diabetes duration (6.7 ± 5.0 years and 7.6 ± 5.8 years, respectively). Hemoglobin A1c was reduced in both groups at 4 months (P<.001), but the reduction was greater with thiazolidinediones than with sitagliptin (-2.0 ± 1.7% vs -1.3 ± 1.8%; P = .006), as was the proportion of patients achieving a hemoglobin A1c level less than 7.5% (62% vs 46%; P = .026). Of all patients achieving a hemoglobin A1c level less than 7.5% at 4 months, the same proportions in each group sustained their hemoglobin A1c level less than 7.5% by 12 months (59% vs 58%). Sitagliptin was well tolerated.

CONCLUSIONS

Among ethnic minority patients with poorly controlled type 2 diabetes while taking maximum tolerated dosages of metformin and sulfonylureas, third-line add-on therapy with a thiazolidinedione controlled hyperglycemia more effectively than sitagliptin after 4 months.

Drug-induced heart failure

PURPOSE

The published evidence on the role of various drugs and medication classes in causing or exacerbating heart failure (HF) is reviewed, with discussion of precautions and management strategies for use in clinical practice.

SUMMARY

A literature search was conducted to identify reports of new-onset HF and exacerbations of HF associated with medication use published from 1960 to January 2011. A large body of evidence from controlled clinical trials has led to an improved understanding of well-established causes of drug-induced HF symptoms (e.g., thiazolidinediones, certain older chemotherapy agents) while implicating a wide range of other commonly used drugs and drug classes (e.g., tyrosine kinase inhibitors, biological response modifiers) as having causal or contributory roles. Among the various medications cited in cases of drug-induced HF, some have been linked to significantly increased risks of stroke, myocardial infarction, and death, particularly in patients with existing cardiovascular (CV) disorders or CV risk factors. In recent years, postmarketing and surveillance data have linked a number of newer medications--including the antiarrhythmic dronedarone, the antifungal itraconazole, and the anti-cancer drugs trastuzumab, lapatinib, and bevacizumab--to serious cardiac effects not reported during clinical trials.

CONCLUSION

A variety of agents have been associated with drug-induced HF. Patients receiving agents that have been implicated in cases of new-onset HF or exacerbations of HF should be monitored for signs and symptoms of CV effects.

Lactic acidosis induced by metformin: incidence, management and prevention

Lactic acidosis associated with metformin treatment is a rare but important adverse event, and unravelling the problem is critical. First, this potential event still influences treatment strategies in type 2 diabetes mellitus, particularly in the many patients at risk of kidney failure, in those presenting contraindications to metformin and in the elderly. Second, the relationship between metformin and lactic acidosis is complex, since use of the drug may be causal, co-responsible or coincidental. The present review is divided into three parts, dealing with the incidence, management and prevention of lactic acidosis occurring during metformin treatment. In terms of incidence, the objective of this article is to counter the conventional view of the link between metformin and lactic acidosis, according to which metformin-associated lactic acidosis is rare but is still associated with a high rate of mortality. In fact, the direct metformin-related mortality is close to zero and metformin may even be protective in cases of very severe lactic acidosis unrelated to the drug. Metformin has also inherited a negative class effect, since the early biguanide, phenformin, was associated with more frequent and sometimes fatal lactic acidosis. In the second part of this review, the objective is to identify the most efficient patient management methods based on our knowledge of how metformin acts on glucose/lactate metabolism and how lactic acidosis may occur (at the organ and cellular levels) during metformin treatment. The liver appears to be a key organ for both the antidiabetic effect of metformin and the development of lactic acidosis; the latter is attributed to mitochondrial impairment and subsequent adenosine triphosphate depletion, acceleration of the glycolytic flux, increased glucose uptake and the generation of lactate, which effluxes into the circulation rather than being oxidized further. Haemodialysis should systematically be performed in severe forms of lactic acidosis, since it provides both symptomatic and aetiological treatment (by eliminating lactate and metformin). In the third part of the review (prevention), the objective is to examine the list of contraindications to metformin (primarily related to renal and cardiovascular function). Diabetes is above all a vascular disease and metformin is a vascular drug with antidiabetic properties. Given the importance of the liver in lactate clearance, we suggest focusing on the severity of and prognosis for liver disease; renal dysfunction is only a prerequisite for metformin accumulation, which may only be dangerous per se when associated with liver failure. Lastly, in view of metformin's impressive overall effectiveness profile, it would be paradoxical to deny the majority of patients with long-established diabetes access to metformin because of the high prevalence of contraindications. The implications of these contraindications are discussed.

Ensuring optimal insulin utilization in the hospital setting: role of the pharmacist

PURPOSE

To summarize essential information for the hospital pharmacist to support the safe and effective use of insulin for the treatment of inpatient hyperglycemia.

SUMMARY

Ensuring optimal insulin utilization in the hospital setting requires collaboration of a multidisciplinary team, including physicians (and endocrinologists specifically), nurses, pharmacists, dieticians, diabetes educators, laboratory staff, quality management staff, and others. The role of pharmacists in this multidisciplinary team is to assist in the standardization of insulin therapy via selection of appropriate insulin treatment protocols, participate in formulary management of insulin products, and contribute to the development of order sets and policies and procedures to minimize the risk of medication errors and misadventures. In addition, pharmacists can provide guidelines or treatment recommendations in special situations, such as those involving patients receiving enteral or parenteral nutrition or high-dose corticosteroids and the transition from i.v. to subcutaneous insulin therapy. Education of patients and providers is another key role for pharmacists. Nurses are important allies in the effort to ensure safe insulin use, as they are at the bedside of patients administering and adjusting insulin therapy. Recommendations are provided for the safe and effective use of insulin for the treatment of inpatient hyperglycemia.

CONCLUSION

Pharmacists are an integral part of the multidisciplinary team ensuring the safe and effective implementation of inpatient hyperglycemic control and insulin usage.

Update on the safety of thiazolidinediones

Diabetic patients are at increased risk for developing cardiovascular disease, and they constitute a large proportion of the global cardiovascular disease burden. Although multiple drugs exist for treating the hyperglycemia associated with diabetes, few have been shown to reduce cardiovascular risk. Great hope surrounded the arrival of the thiazolidinediones-drugs that favorably affect insulin sensitivity, inflammation, and some aspects of lipid profiles in diabetic patients. However, the cardiovascular effects of these agents are varied, and studies have suggested that they may be associated with increases in ischemic heart disease and heart failure, as well as with an increased risk for bone fracture. The following article provides a summary of important studies that have been published regarding the safety profiles of these agents. Findings from two recently published trials, RECORD and BARI 2D, are emphasized in this paper.