The ‘Forgotten’ Bile Acid Sequestrants: Is Now a Good Time to Remember?

Bile Acid Sequestrants Based on Natural and Synthetic Gels

Bile acid sequestrants (BASs) are non-systemic therapeutic agents used for the management of hypercholesterolemia. They are generally safe and not associated with serious systemic adverse effects. Usually, BASs are cationic polymeric gels that have the ability to bind bile salts in the small intestine and eliminate them by excretion of the non-absorbable polymer-bile salt complex. This review gives a general presentation of bile acids and the characteristics and mechanisms of action of BASs. The chemical structures and methods of synthesis are shown for commercial BASs of first- (cholestyramine, colextran, and colestipol) and second-generation (colesevelam and colestilan) and potential BASs. The latter are based on either synthetic polymers such as poly((meth)acrylates/acrylamides), poly(alkylamines), poly(allylamines) and vinyl benzyl amino polymers or biopolymers, such as cellulose, dextran, pullulan, methylan, and poly(cyclodextrins). A separate section is dedicated to molecular imprinting polymers (MIPs) because of their great selectivity and affinity for the template molecules used in the imprinting technique. Focus is given to the understanding of the relationships between the chemical structure of these cross-linked polymers and their potential to bind bile salts. The synthetic pathways used in obtaining BASs and their in vitro and in vivo hypolipidemic activities are also introduced.

Effects of Atorvastatin on Bile Acid Metabolism in High-fat Diet-fed ApoE -/- Mice

ABSTRACT

Statins are considered as the cornerstone of the prevention and treatment of atherosclerotic cardiovascular disease, where pleiotropic effects are thought to contribute greatly in addition to the lipid-lowering effect. Bile acid metabolism has been gradually reported to be involved in the antihyperlipidemic and antiatherosclerotic effects of statins, but with inconsistent results and few studies carried out on animal models of atherosclerosis. The study aimed to examine the possible role of bile acid metabolism in the lipid-lowering and antiatherosclerotic effects of atorvastatin (ATO) in high-fat diet-fed ApoE -/- mice. The results showed that the levels of liver and faecal TC as well as ileal and faecal TBA were significantly increased in mice of the model group after 20 weeks of high-fat diet feeding compared with the control group, with significantly downregulated mRNA expression of liver LXR-α, CYP7A1, BSEP, and NTCP. ATO treatment further increased the levels of ileal and faecal TBA and faecal TC, but no obvious effect was observed on serum and liver TBA. In addition, ATO significantly reversed the mRNA levels of liver CYP7A1 and NTCP, and no obvious changes were observed in the expression of LXR-α and BSEP. Our study suggested that statins may enhance the synthesis of bile acids and facilitate the reabsorption of bile acids from the ileum via portal into the liver, possibly through the upregulation of the expression of CYP7A1 and NTCP. The results are helpful in enriching the theoretical basis for the clinical use of statins and have good translational value.

Emerging Roles of Gut Microbial Modulation of Bile Acid Composition in the Etiology of Cardiovascular Diseases

Despite advances in preventive measures and treatment options, cardiovascular disease (CVD) remains the number one cause of death globally. Recent research has challenged the traditional risk factor profile and highlights the potential contribution of non-traditional factors in CVD, such as the gut microbiota and its metabolites. Disturbances in the gut microbiota have been repeatedly associated with CVD, including atherosclerosis and hypertension. Mechanistic studies support a causal role of microbiota-derived metabolites in disease development, such as short-chain fatty acids, trimethylamine-N-oxide, and bile acids, with the latter being elaborately discussed in this review. Bile acids represent a class of cholesterol derivatives that is essential for intestinal absorption of lipids and fat-soluble vitamins, plays an important role in cholesterol turnover and, as more recently discovered, acts as a group of signaling molecules that exerts hormonal functions throughout the body. Studies have shown mediating roles of bile acids in the control of lipid metabolism, immunity, and heart function. Consequently, a picture has emerged of bile acids acting as integrators and modulators of cardiometabolic pathways, highlighting their potential as therapeutic targets in CVD. In this review, we provide an overview of alterations in the gut microbiota and bile acid metabolism found in CVD patients, describe the molecular mechanisms through which bile acids may modulate CVD risk, and discuss potential bile-acid-based treatment strategies in relation to CVD.

Bile acid metabolism and signaling, the microbiota, and metabolic disease

The diversity, composition, and function of the bacterial community inhabiting the human gastrointestinal tract contributes to host health through its role in producing energy or signaling molecules that regulate metabolic and immunologic functions. Bile acids are potent metabolic and immune signaling molecules synthesized from cholesterol in the liver and then transported to the intestine where they can undergo metabolism by gut bacteria. The combination of host- and microbiota-derived enzymatic activities contribute to the composition of the bile acid pool and thus there can be great diversity in bile acid composition that depends in part on the differences in the gut bacteria species. Bile acids can profoundly impact host metabolic and immunological functions by activating different bile acid receptors to regulate signaling pathways that control a broad range of complex symbiotic metabolic networks, including glucose, lipid, steroid and xenobiotic metabolism, and modulation of energy homeostasis. Disruption of bile acid signaling due to perturbation of the gut microbiota or dysregulation of the gut microbiota-host interaction is associated with the pathogenesis and progression of metabolic disorders. The metabolic and immunological roles of bile acids in human health have led to novel therapeutic approaches to manipulate the bile acid pool size, composition, and function by targeting one or multiple components of the microbiota-bile acid-bile acid receptor axis.

Anti-Obesity Medications and Investigational Agents: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This "Anti-Obesity Medications and Investigational Agents: An Obesity Medicine Association Clinical Practice Statement 2022" is intended to provide clinicians an overview of Food and Drug Administration (FDA) approved anti-obesity medications and investigational anti-obesity agents in development.

Methods

The scientific information for this Clinical Practice Statement (CPS) is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

This CPS describes pharmacokinetic principles applicable to those with obesity, and discusses the efficacy and safety of anti-obesity medications [e.g., phentermine, semaglutide, liraglutide, phentermine/topiramate, naltrexone/bupropion, and orlistat, as well as non-systemic superabsorbent oral hydrogel particles (which is technically classified as a medical device)]. Other medications discussed include setmelanotide, metreleptin, and lisdexamfetamine dimesylate. Data regarding the use of combination anti-obesity pharmacotherapy, as well as use of anti-obesity pharmacotherapy after bariatric surgery are limited; however, published data support such approaches. Finally, this CPS discusses investigational anti-obesity medications, with an emphasis on the mechanisms of action and summary of available clinical trial data regarding tirzepatide.

Conclusion

This "Anti-Obesity Medications and Investigational Agents: An Obesity Medicine Association Clinical Practice Statement 2022" is one of a series of OMA CPSs designed to assist clinicians in the care of patients with pre-obesity/obesity.

Bempedoic acid in patients with type 2 diabetes mellitus, prediabetes, and normoglycaemia: A post hoc analysis of efficacy and glycaemic control using pooled data from phase 3 clinical trials

AIM

To evaluate the effect of bempedoic acid on glycaemic and lipid variables in patients with hypercholesterolaemia.

METHODS

A patient-level pooled analysis of four phase 3, randomized, double-blind, placebo-controlled trials evaluated changes in glycaemia, change from baseline in LDL-C, and adverse events. Patients (N = 3621) on maximally tolerated statins were randomized 2:1 to oral bempedoic acid 180 mg or placebo once daily for 12 to 52 weeks with the results analysed by baseline glycaemic status (diabetes, prediabetes, or normoglycaemia).

RESULTS

The annual rate of new-onset diabetes for bempedoic acid versus placebo in patients with normoglycaemia at baseline (n = 618) was 0.3% versus 0.8%, and for patients with prediabetes at baseline (n = 1868) it was 4.7% versus 5.9%. In patients with diabetes or prediabetes, bempedoic acid significantly (P < .0001) reduced HbA1c by -0.12% and -0.06%, respectively, and did not worsen fasting glucose versus placebo. Bempedoic acid significantly and consistently lowered LDL-C levels versus placebo, regardless of baseline glycaemic status (placebo-corrected difference range, -17.2% to -29.6%; P < .001 for each stratum). The safety of bempedoic acid was comparable with placebo and similar across glycaemic strata.

CONCLUSIONS

Bempedoic acid significantly lowered LDL-C across glycaemic strata and did not worsen glycaemic variables or increase the incidence of new-onset diabetes versus placebo over a median follow-up of 1 year.

Bile Acid Sequestrants for Hypercholesterolemia Treatment Using Sustainable Biopolymers: Recent Advances and Future Perspectives

Bile acids, the endogenous steroid nucleus containing signaling molecules, are responsible for the regulation of multiple metabolic processes, including lipoprotein and glucose metabolism to maintain homeostasis. Within our body, they are directly produced from their immediate precursors, cholesterol C (low-density lipoprotein C, LDL-C), through the enzymatic catabolic process mediated by 7-α-hydroxylase (CYP7A1). Bile acid sequestrants (BASs) or amphiphilic resins that are nonabsorbable to the human body (being complex high molecular weight polymers/electrolytes) are one of the classes of drugs used to treat hypercholesterolemia (a high plasma cholesterol level) or dyslipidemia (lipid abnormalities in the body); thus, they have been used clinically for more than 50 years with strong safety profiles as demonstrated by the Lipid Research Council-Cardiovascular Primary Prevention Trial (LRC-CPPT). They reduce plasma LDL-C and can slightly increase high-density lipoprotein C (HDL-C) levels, whereas many of the recent clinical studies have demonstrated that they can reduce glucose levels in patients with type 2 diabetes mellitus (T2DM). However, due to higher daily dosage requirements, lower efficacy in LDL-C reduction, and concomitant drug malabsorption, research to develop an "ideal" BAS from sustainable or natural sources with better LDL-C lowering efficacy and glucose regulations and lower side effects is being pursued. This Review discusses some recent developments and their corresponding efficacies as bile removal or LDL-C reduction of natural biopolymer (polysaccharide)-based compounds.

Bile salts adsorption on dextran-based hydrogels

Dextran-based gels bearing two types of pendant N, N-dimethyl-N-alkyl-N-(2-hydroxypropyl) ammonium chloride groups with different alkyl chain length substituents (C₂ and C₁₂/C₁₆, respectively) at the quaternary nitrogen were synthesized and structural characteristics of the compounds were studied by elemental analysis, potentiometric titration, FTIR and NMR spectroscopy. The morphology and size of polymeric microspheres were examined by SEM and their swelling behavior in water was also investigated. The hydrogels were evaluated as sorbents for sodium cholate (NaCA) and sodium deoxycholate (NaDCA) in water and 10 mM NaCl solutions. Different isotherm models (nearest-neighbor-interaction, Langmuir, Freundlich, Dubinin-Raduskevich, Sips and Hill) were used to elucidate the adsorption mechanism and established the characteristics of the most efficient polymeric sorbent. The maximum adsorption capacity of the gels was highly controlled by gel hydrophobicity which enhanced gel-bile salt affinity but decreased binding cooperativity. Swelling porosity, ionic strength and ligand lipophilicity were other factors that also affected the adsorption process. The hydrogel having 25 mol% pendant dodecyl groups retained the maximum amount of bile salts (1051 mg NaCA/g and 1138 mg NaDCA/g). All hydrophobically modified hydrogels revealed a better affinity and strength of binding compared to commercial Cholestyramine®.

PCSK9 Inhibitors

Objective: To evaluate the safety and efficacy of 2 human monoclonal antibodies, alirocumab and evolocumab, on reduction of low-density lipoprotein cholesterol (LDL-C), cardiovascular benefits, and their place in current practice. Data Sources: A search of MEDLINE and Scopus databases (1966 to May 2016) with search terms “alirocumab,” “evolocumab,” “LDL,” and “PCSK9.” Study Selection and Data Extraction: The search identified phase 3 randomized control trials in English language in the past 10 years that studied LDL-C reduction of alirocumab or evolocumab. The studies were assessed for all efficacy and safety endpoints. Data Synthesis: Twelve total studies were identified evaluating alirocumab or evolocumab. These monoclonal antibodies have been shown to significantly decrease LDL-C as monotherapy and in combination with statins in phase 3 clinical trials in patients with primary hypercholesterolemia as well as familial hypercholesterolemia by inhibiting PCSK9. Alirocumab significantly reduced LDL-C by up to 61%, while evolocumab significantly reduced LDL-C by up to 66%. Adverse effects of these medications have been low and overall well tolerated. Conclusion: Although these monoclonal antibodies have shown to significantly reduce LDL-C, their effect on cardiovascular outcomes has not yet been determined. Further studies are being conducted to assess the cardiovascular benefit of both alirocumab and evolocumab. Until these studies demonstrate a reduction in atherosclerotic cardiovascular disease risk, statins should remain first-line therapy for most patients. However, alirocumab and evolocumab can be used as an effective adjunctive therapy option to lower LDL-C or in patients who are statin intolerant.

Randomized double blind clinical trial on the effect of oral α-cyclodextrin on serum lipids

Background

This single center, double-blinded, cross-over, placebo controlled clinical trial investigated the effect of oral α-cyclodextrin (α-CD), a soluble dietary fiber, on blood lipid and lipoprotein levels in healthy human subjects. α-CD, a cyclical polymer containing 6 glucose subunits, is currently sold as an over the counter food supplement and is also a common additive in many foods. α-CD forms a hydrophobic central cavity that binds lipids and has been shown in animal studies and in previous clinical trials to alter plasma lipid levels.

Methods

We screened for healthy subjects, males and females, between ages 18 to 75. Out of total 103 subjects interviewed, 75 subjects completed the study. Qualified individuals in each gender group were randomized into two groups in terms of which treatment arm they received first (placebo vs. α-CD, receiving 6 grams P.O. a day, for 12–14 weeks with a 7 day wash out between arms). The primary outcome variable, plasma total cholesterol, as well as other tests related to lipids and lipoprotein and glucose metabolism, were measured at baseline and at the end of each arm of the study.

Results

α-CD was well tolerated; no serious adverse events related to α-CD were observed. Approximately 8 % of the subjects on α-CD complained of minor gastrointestinal symptoms versus 3 % on placebo (p = 0.2). Small-LDL particle number decreased 10 % (p < 0.045) for subjects on α-CD versus placebo. Fasting plasma glucose (1.6 %, p < 0.05) and Insulin resistance index (11 %, p < 0.04) were also decreased when on α-CD versus placebo.

Conclusion

α-CD treatment appears to be safe and well tolerated in healthy individuals and showed a modest reduction in small LDL particles, and an improvement in glucose related parameters.

Trial registration

NCT01131299

Trends in the Use of Nonstatin Lipid-Lowering Therapy Among Patients With Coronary Heart Disease: A Retrospective Cohort Study in the Medicare Population 2007 to 2011

BACKGROUND

Nonstatin lipid-lowering therapy is adjunctive therapy for high-risk individuals on statins or monotherapy among those who cannot tolerate statins.

OBJECTIVES

This study determined time trends between 2007 and 2011 for statin and nonstatin lipid-lowering therapy (niacin, fibrates, bile acid sequestrants, and ezetimibe) use among Medicare beneficiaries with coronary heart disease (CHD) in light of emerging clinical trial evidence.

METHODS

We conducted a retrospective cohort study using the national 5% random sample of Medicare beneficiaries (n = 310,091). We created 20 cohorts of individuals with CHD, representing calendar quarters from 2007 through 2011, to assess trends in use of statins and nonstatin lipid-lowering medications.

RESULTS

Statin use increased from 53.1% to 58.8% between 2007 and 2011. Ezetimibe use peaked at 12.1% and declined to 4.6% by the end of 2011, declining among both patients on statins (18.4% to 6.2%) and not on statins (5.0% to 2.4%). Fibrate use increased from 4.2% to 5.0%, bile acid sequestrants did not change significantly, and niacin use increased from 1.5% to 2.4% and then declined in late 2011. Use of nonstatin lipid-lowering therapy was less common at older age, among African Americans, patients with heart failure, and patients with a higher Charlson comorbidity score. Nonstatin lipid-lowering therapy use was more common among men and patients with diabetes, those who had cardiologist visits, and among those taking statins.

CONCLUSIONS

Declining ezetimibe and niacin use but not fibrate therapy among Medicare beneficiaries with CHD coincides with negative clinical trial results for these agents.

A lipidologist perspective of global lipid guidelines and recommendations, part 2: Lipid treatment goals

Having knowledge of worldwide areas of harmonization and consensus regarding lipid guidelines and recommendations may provide clinicians a more global perspective on lipid management. This review examines 8 international scientific/medical organizations that have issued lipid guidelines, recommendations, and position papers: the National Lipid Association (2014), National Institute for Health and Care Excellence (2014), International Atherosclerosis Society (2013), American College of Cardiology/American Heart Association (2013), Canadian Cardiovascular Society (2013), Japan Atherosclerosis Society (2012), European Society of Cardiology/European Atherosclerosis Society (2012), and Adult Treatment Panel III (2001/2004). Part 1 of this perspective focused on sentinel components of these lipid guidelines and recommendations as applied to the role of atherogenic lipoprotein cholesterol levels, primary lipid target of therapy, other primary and secondary lipid treatment targets, and assessment of atherosclerotic cardiovascular disease (ASCVD) risk. This part 2 examines goals of lipid-altering therapy. While lipid guidelines and recommendations may differ regarding ASCVD risk assessment and lipid treatment goals, lipid guidelines and recommendations generally agree on the need to reduce atherogenic lipoprotein cholesterol levels, with statins being the first-line treatment of choice.

Alirocumab as Add-On to Atorvastatin Versus Other Lipid Treatment Strategies: ODYSSEY OPTIONS I Randomized Trial

CONTEXT

Despite current standard of care, many patients at high risk of cardiovascular disease (CVD) still have elevated low-density lipoprotein cholesterol (LDL-C) levels. Alirocumab is a fully human monoclonal antibody inhibitor of proprotein convertase subtilisin/kexin type 9.

OBJECTIVE

The objective of the study was to compare the LDL-C-lowering efficacy of adding alirocumab vs other common lipid-lowering strategies.

DESIGN, PATIENTS, AND INTERVENTIONS

Patients (n = 355) with very high CVD risk and LDL-C levels of 70 mg/dL or greater or high CVD risk and LDL-C of 100 mg/dL or greater on baseline atorvastatin 20 or 40 mg were randomized to one of the following: 1) add-on alirocumab 75 mg every 2 weeks (Q2W) sc; 2) add-on ezetimibe 10 mg/d; 3) double atorvastatin dose; or 4) for atorvastatin 40 mg regimen only, switch to rosuvastatin 40 mg. For patients not achieving protocol-defined LDL-C goals, the alirocumab dose was increased (blinded) at week 12 to 150 mg Q2W.

MAIN OUTCOME MEASURE

The primary end point was percentage change in calculated LDL-C from baseline to 24 weeks (intent to treat).

RESULTS

Among atorvastatin 20 and 40 mg regimens, respectively, add-on alirocumab reduced LDL-C levels by 44.1% and 54.0% (P < .001 vs all comparators); add-on ezetimibe, 20.5% and 22.6%; doubling of atorvastatin dose, 5.0% and 4.8%; and switching atorvastatin 40 mg to rosuvastatin 40 mg, 21.4%. Most alirocumab-treated patients (87.2% and 84.6%) achieved their LDL-C goals. Most alirocumab-treated patients (86%) maintained their 75-mg Q2W regimen. Treatment-emergent adverse events occurred in 65.4% of alirocumab patients vs 64.4% ezetimibe and 63.8% double atorvastatin/switch to rosuvastatin (data were pooled).

CONCLUSIONS

Adding alirocumab to atorvastatin provided significantly greater LDL-C reductions vs adding ezetimibe, doubling atorvastatin dose, or switching to rosuvastatin and enabled greater LDL-C goal achievement.

Cardiovascular mortality in chronic kidney disease patients: potential mechanisms and possibilities of inhibition by resin-based phosphate binders

Cardiovascular mortality has been considered as the most important risk associated with chronic kidney disease. The mechanisms underlying this include inflammation, poor control of serum phosphate, high serum calcium, increased calcification of the arteries and cardiac valves, hyperlipidemia, diabetes, severe anemia, uric acid accumulation and others. Elevated phosphate levels have been strongly associated with increased mortality, thus phosphate-binding drugs have long been used to control the increase serum phosphate levels. However, phosphate-binding drugs differ considerably and recently numerous publications suggest differences between agents in the effects on overall mortality. The resin-based phosphate binders, comprising sevelamer and colestilan, not only reduce serum phosphate but also do not raise serum calcium. In addition, they reduce serum LDL-C, inflammation, uric acid and high Hba1c values. These differences suggest that not all phosphate binders may be equal in the context of cardiovascular mortality in this patient population.

Colestilan for the treatment of hyperphosphatemia in chronic kidney disease patients on dialysis

Chronic kidney disease in the later stages poses many treatment challenges. Hyperphosphatemia is one that is well-known and is often linked to increased cardiovascular morbidity/mortality. Currently, a number of phosphate binders are available that act to conserve serum phosphate at normal or near normal levels. However, it is the overall profile of all binders that needs to be taken into account and the risks and the potential benefits associated with each agent must be balanced when selecting a particular phosphate binder. It is known that calcium-based binders, although effective phosphate binders, may lead to hypercalcemia and/or positive calcium balance and cardiovascular calcification. One, new non-calcium phosphate binder, recently approved in Europe, is colestilan. Colestilan possesses a range of properties that may afford further advantages over simply reducing serum phosphate. This review assesses the pharmacology and clinical data of colestilan used to treat hyperphosphatemia in chronic kidney disease stage 5 patients on dialysis. The article was written based on literature searches using PubMed to find articles published on phosphate binders or colestilan over the last 10 years.

Lowering low-density lipoprotein cholesterol levels in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia, insulin resistance, and/or progressive loss of β-cell function. T2DM patients are at increased risk of micro- and macrovascular disease, and are often considered as representing an atherosclerotic coronary heart disease (CHD) risk equivalent. Interventions directed at glucose and lipid level control in T2DM patients may reduce micro- and macrovascular disease. The optimal T2DM agent is one that lowers glucose levels with limited risk for hypoglycemia, and with no clinical trial evidence of worsening CHD risk. Lipid-altering drugs should preferably reduce low-density lipoprotein cholesterol and apolipoprotein B (apo B) and have evidence that the mechanism of action reduces CHD risk. Statins reduce low-density lipoprotein cholesterol and apo B and have evidence of improving CHD outcomes, and are thus first-line therapy for the treatment of hypercholesterolemia. In patients who do not achieve optimal lipid levels with statin therapy, or who are intolerant to statin therapy, add-on therapy or alternative therapies may be indicated. Additional available agents to treat hypercholesterolemic patients with T2DM include bile acid sequestrants, fibrates, niacin, and ezetimibe. This review discusses the use of these alternative agents to treat hypercholesterolemia in patients with T2DM, either as monotherapy or in combination with statin therapy.

Lack of effect of colesevelam HCl on the single-dose pharmacokinetics of aspirin, atenolol, enalapril, phenytoin, rosiglitazone, and sitagliptin

AIMS

Drug interactions with bile acid sequestrants are primarily due to the potential of these agents to bind to concomitant drugs. Six clinical studies were performed to determine the effects of colesevelam on the pharmacokinetics of aspirin, atenolol, enalapril, phenytoin, rosiglitazone, and sitagliptin.

METHODS

All six studies enrolled healthy subjects aged 18-45 years. The phenytoin study used a single-dose, three-period crossover design (phenytoin alone, phenytoin simultaneously with colesevelam, and phenytoin 4h before colesevelam). The other studies used a two-period crossover design (test drug alone and test drug simultaneously with colesevelam). Colesevelam (3750mg once daily) was dosed throughout the pharmacokinetic sampling period. After each single dose of the test drug, serial blood samples were collected for determination of plasma drug concentrations and calculation of pharmacokinetic parameters.

RESULTS

For all six test drugs, 90% CIs for geometric least-squares mean ratios of AUC and Cmax for the measured analytes were within specified limits, indicating no interaction between the test drug and colesevelam.

CONCLUSIONS

Aspirin, atenolol, enalapril, rosiglitazone, and sitagliptin may be taken with colesevelam. Although the phenytoin study indicated no pharmacokinetic interaction, phenytoin should continue to be taken ≥4h before colesevelam in accordance with current prescribing information.

Colesevelam, Ezetimibe, and Patients With Type 2 Diabetes Mellitus: Characteristics and Clinical Outcomes From a Health Care Database

BACKGROUND

Despite the prevalence of therapies available to patients at highest coronary heart disease risk, only a minority of type 2 diabetes mellitus (T2DM) patients reach desired cholesterol treatment levels, with limited data regarding their outcomes.

OBJECTIVE

To examine "real-world" effectiveness of initiating treatment with either colesevelam or ezetimibe among individuals with evidence of T2DM and hypercholesterolemia (HCh). Key outcomes included treatment patterns and cardiovascular (CV) events.

METHODS

This retrospective administrative claims-based study utilized medical, pharmacy, and enrollment data linked to laboratory results information from a large United States health plan (January 1, 2006, to March 31, 2011) and included individuals with recorded evidence of T2DM and HCh. The index date was the date of first pharmacy claim for colesevelam or ezetimibe, with cohort assignment based on index medication. Assessments included baseline characteristics, follow-up treatment patterns, and composite CV event, with propensity score matching to correct for sample selection bias.

RESULTS

In total, 4231 individuals were identified with evidence of HCh and T2DM (ezetimibe n = 3384; colesevelam n = 847). After matching, the baseline characteristics between cohorts were rendered to be similar. Mean days of persistent medication use was lower with colesevelam compared with ezetimibe (P < 0.001). Compared with ezetimibe, a smaller percentage of individuals in the colesevelam cohort experienced a follow-up composite CV event, and adjusted Cox model results suggested decreased risk (hazard ratio = 0.58; P = 0.004) of a follow-up composite CV event.

CONCLUSION

In this health care database analysis among patients with HCh and T2DM, colesevelam was associated with decreased risk of a composite CV event compared with ezetimibe, despite lower persistence.

A reappraisal of the risks and benefits of treating to target with cholesterol lowering drugs

Atherosclerotic cardiovascular disease (CVD) is the number one cause of death globally, and lipid modification, particularly lowering of low density lipoprotein cholesterol (LDLc), is one of the cornerstones of prevention and treatment. However, even after lowering of LDLc to conventional goals, a sizeable number of patients continue to suffer cardiovascular events. More aggressive lowering of LDLc and optimization of other lipid parameters like triglycerides (TG) and high density lipoprotein cholesterol (HDLc) have been proposed as two potential strategies to address this residual risk. These strategies entail use of maximal doses of highly potent HMG CoA reductase inhibitors (statins) and combination therapy with other lipid modifying agents. Though statins in general are fairly well tolerated, adverse events like myopathy are dose related. There are further risks with combination therapy. In this article, we review the adverse effects of lipid modifying agents used alone and in combination and weigh these effects against the evidence demonstrating their efficacy in reducing cardiovascular events, cardiovascular mortality, and all cause mortality. For patients with established CVD, statins are the only group of drugs that have shown consistent reductions in hard outcomes. Though more aggressive lipid lowering with high dose potent statins can reduce rates of non fatal events and need for interventions, the incremental mortality benefits remain unclear, and their use is associated with a higher rate of drug related adverse effects. Myopathy and renal events have been a significant concern with the use of high potency statin drugs, in particular simvastatin and rosuvastatin. For patients who have not reached target LDL levels or have residual lipid abnormalities on maximal doses of statins, the addition of other agents has not been shown to improve clinical outcomes and carries an increased risk of adverse events. The clinical benefits of drugs to raise HDLc remain unproven. In patients without known cardiovascular disease, there is conflicting evidence as to the benefits of aggressive pursuit of numerical lipid targets, particularly with respect to all cause mortality. Certainly, in statin intolerant patients, alternative agents with a low side effect profile are desirable. Bile acid sequestrants are an effective and safe choice for decreasing LDLc, and omega-3 fatty acids are safe agents to decrease TG. There remains an obvious need to design and carry out large scale studies to help determine which agents, when combined with statins, have the greatest benefit on cardiovascular disease with the least added risk. These studies should be designed to assess the impact on clinical outcomes rather than surrogate endpoints, and require a comprehensive assessment and reporting of safety outcomes.

Clinical relevance of target identity and biology: implications for drug discovery and development

Many of the most commonly used drugs precede techniques for target identification and drug specificity and were developed on the basis of efficacy and safety, an approach referred to as classical pharmacology and, more recently, phenotypic drug discovery. Although substantial gains have been made during the period of focus on target-based approaches, particularly in oncology, these approaches have suffered a high overall failure rate and lower productivity in terms of new drugs when compared with phenotypic approaches. This review considers the importance of target identity and biology in clinical practice from the prescriber's viewpoint. In evaluating influences on prescribing behavior, studies suggest that target identity and mechanism of action are not significant factors in drug choice. Rather, patients and providers consistently value efficacy, safety, and tolerability. Similarly, the Food and Drug Administration requires evidence of safety and efficacy for new drugs but does not require knowledge of drug target identity or target biology. Prescribers do favor drugs with novel mechanisms, but this preference is limited to diseases for which treatments are either not available or suboptimal. Thus, while understanding of drug target and target biology is important from a scientific perspective, it is not particularly important to prescribers, who prioritize efficacy and safety.

rHDL administration increases reverse cholesterol transport in mice, but is not additive on top of ezetimibe or cholestyramine treatment

OBJECTIVE

Promoting reverse cholesterol transport (RCT) is a major atheroprotective property of HDL. The present study explored the effect of stimulating the first step of RCT (cholesterol efflux from macrophages) alone or in combination with stimulating the last step of RCT (fecal sterol excretion).

METHODS AND RESULTS

Reconstituted HDL (rHDL) was injected into wild-type mice either with or without administration of the cholesterol absorption inhibitor ezetimibe or the bile acid sequestrant cholestyramine. Single dose administration of rHDL (100 mg apoA-I/kg) resulted in an early (4 h) increase in plasma free cholesterol levels (p < 0.001), without affecting hepatic cholesterol levels or fecal mass sterol excretion. rHDL injection also increased [(3)H]cholesterol appearance in plasma at an early time-point (4 h) after intraperitoneal administration of [(3)H]cholesterol-labeled mouse macrophage foam cells and fecal radioactivity excretion indicating completed RCT was increased by 26% (p < 0.05). Ezetimibe treatment inhibited intestinal cholesterol absorption by 74% (p < 0.01), but also the bile acid sequestrant cholestyramine decreased cholesterol absorption significantly (24%, p < 0.01). Consequently, ezetimibe increased RCT 2.1-fold (p < 0.001) primarily within fecal neutral sterols, while cholestyramine increased RCT by 3.6-fold (p < 0.001), primarily within bile acids (p < 0.001), but also within neutral sterols (p < 0.001). However, no additive effects of both intestinal sterol uptake inhibitors were observed on top of rHDL administration.

CONCLUSION

These data demonstrate that increasing the first step of RCT by rHDL administration results in transient cholesterol mobilization from macrophages to plasma. This effect is not further enhanced by stimulating the last step of RCT, fecal sterol excretion.

Colestilan decreases weight gain by enhanced NEFA incorporation in biliary lipids and fecal lipid excretion

Bile acid sequestrants (BASs) are cholesterol-lowering drugs that also affect hyperglycemia. The mechanism by which BASs exert these and other metabolic effects beyond cholesterol lowering remains poorly understood. The present study aimed to investigate the effects of a BAS, colestilan, on body weight, energy expenditure, and glucose and lipid metabolism and its mechanisms of action in high-fat-fed hyperlipidemic APOE*3 Leiden (E3L) transgenic mice. Mildly insulin-resistant E3L mice were fed a high-fat diet with or without 1.5% colestilan for 8 weeks. Colestilan treatment decreased body weight, visceral and subcutaneous fat, and plasma cholesterol and triglyceride levels but increased food intake. Blood glucose and plasma insulin levels were decreased, and hyperinsulinemic-euglycemic clamp analysis demonstrated improved insulin sensitivity, particularly in peripheral tissues. In addition, colestilan decreased energy expenditure and physical activity, whereas it increased the respiratory exchange ratio, indicating that colestilan induced carbohydrate catabolism. Moreover, kinetic analysis revealed that colestilan increased [(3)H]NEFA incorporation in biliary cholesterol and phospholipids and increased fecal lipid excretion. Gene expression analysis in liver, fat, and muscle supported the above findings. In summary, colestilan decreases weight gain and improves peripheral insulin sensitivity in high-fat-fed E3L mice by enhanced NEFA incorporation in biliary lipids and increased fecal lipid excretion.

Adiposopathy, diabetes mellitus, and primary prevention of atherosclerotic coronary artery disease: treating "sick fat" through improving fat function with antidiabetes therapies

Both obesity and type 2 diabetes mellitus (DM) are worldwide epidemics, an association that is neither incidental nor coincidental. Adipose tissue is as an active endocrine and immune organ whose dysfunction (adiposopathy or "sick fat") is promoted by excessive caloric balance in genetically and environmentally susceptible patients. The resultant adiposopathic responses directly and indirectly contribute to pathologies leading to hyperglycemia, high blood pressure, and dyslipidemia--all major cardiovascular risk factors--as well as to cardiovascular disease (CVD) itself. Toward the goal of primary prevention of CVD among DM patients, clinical trial outcomes evidence support the use of antihypertensive agents, lipid-altering drugs, and antiplatelet agents. Some of the most proactive measures to reduce the onset of cardiovascular risk factors and potentially prevent the onset of DM are early and aggressive nutritional, physical activity, and lifestyle interventions. Such measures improve the functionality of adipose tissue, reduce adiposopathic responses, and thus improve glycemic, blood pressure, and lipid parameters--all of which would be expected to reduce CVD risk. Finally, if nutritional, physical activity, and lifestyle interventions are not successful, and if DM pharmacologic therapies are indicated, then the choice of anti-DM medications should take into consideration the effects of such agents on adipose tissue function and dysfunction, which in turn, affects major CVD risk factors and CVD.

Inhibition of cholesterol absorption: targeting the intestine

Atherosclerosis, the gradual formation of a lipid-rich plaque in the arterial wall is the primary cause of Coronary Artery Disease (CAD), the leading cause of mortality worldwide. Hypercholesterolemia, elevated circulating cholesterol, was identified as a key risk factor for CAD in epidemiological studies. Since the approval of Mevacor in 1987, the primary therapeutic intervention for hypercholesterolemia has been statins, drugs that inhibit the biosynthesis of cholesterol. With improved understanding of the risks associated with elevated cholesterol levels, health agencies are recommending reductions in cholesterol that are not achievable in every patient with statins alone, underlying the need for improved combination therapies. The whole body cholesterol pool is derived from two sources, biosynthesis and diet. Although statins are effective at reducing the biosynthesis of cholesterol, they do not inhibit the absorption of cholesterol, making this an attractive target for adjunct therapies. This report summarizes the efforts to target the gastrointestinal absorption of cholesterol, with emphasis on specifically targeting the gastrointestinal tract to avoid the off-target effects sometimes associated with systemic exposure.

Glucose and low-density lipoprotein cholesterol lowering in elderly patients with type 2 diabetes: focus on combination therapy with colesevelam HCl

The prevalence of type 2 diabetes mellitus is high among the elderly population. Treatment of elderly patients with type 2 diabetes presents challenges because of co-morbidities and the potential increase in the risk of adverse effects. Hyperlipidaemia is also common in the elderly population. Glucose-and lipid-lowering treatment in elderly patients should be individualized on the basis of the patient’s life expectancy, health status and cardiovascular risk factors, and evidence-based guideline recommendations. Because elderly patients often have impaired renal and hepatic function, careful considerations must be made when selecting appropriate glucose- and lipid-lowering therapy. There are a number of potential safety issues associated with various glucose- and lipid-lowering therapies that are relevant to elderly patients, including increased risk of heart failure exacerbations, weight loss, increased risk of hypoglycaemia, increased risk of myopathy, and contraindications of some agents in patients with hepatic or renal impairment. The bile acid sequestrant colesevelam HCl is unique compared with other glucose- and lipid-lowering therapies because it is the only product approved by the US Food and Drug Administration, as an adjunct to diet and exercise, to lower both glucose and low-density lipoprotein cholesterol (LDL-C) in adults with type 2 diabetes and primary hyperlipidaemia, respectively. Furthermore, colesevelam has been shown to have similar glucose- and lipid-lowering efficacy in patients aged <65 years and those aged ≥65 years. Colesevelam was not associated with weight gain, was associated with a low incidence of hypoglycaemia, and can be safely combined with a broad range of glucose-lowering agents (metformin, sulfonylureas and insulin) and lipid-lowering statins. Currently, colesevelam is available in tablet form and as a powder for oral suspension formulation; the latter may be of benefit to elderly patients with swallowing difficulties. As colesevelam has both glucose- and lipid-lowering effects, its use may reduce the drug burden in elderly patients receiving multiple agents for glucose and lipid lowering. Colesevelam may be a valuable treatment option as an add-on to existing glucose- and/or lipid-lowering therapy to help improve haemoglobin A_1c and to lower LDL-C levels in elderly patients with type 2 diabetes and primary hyperlipidaemia.

Colesevelam hydrochloride: evidence for its use in the treatment of hypercholesterolemia and type 2 diabetes mellitus with insights into mechanism of action

Colesevelam hydrochloride is a molecularly engineered, second-generation bile acid sequestrant demonstrating enhanced specificity for bile acids which has been approved for use as adjunctive therapy to diet and exercise as monotherapy or in combination with a β-hydroxymethylglutaryl-coenzyme A reductase inhibitor for the reduction of elevated low-density lipoprotein cholesterol in patients with primary hypercholesterolemia. It is also the only lipid-lowering agent currently available in the United States which has been approved for use as adjunctive therapy in patients with type 2 diabetes mellitus whose glycemia remains inadequately controlled on therapy with metformin, sulfonylurea, or insulin. With the recent emphasis upon drug safety by the Food and Drug Administration and various consumer agencies, it is fitting that the role of nonsystemic lipid-lowering therapies such as bile acid sequestrants – with nearly 90 years of in-class, clinically safe experience – should be reexamined. This paper presents information on the major pharmacologic effects of colesevelam, including a discussion of recent data derived from both in vitro and in vivo rodent and human studies, which shed light on the putative mechanisms involved.

Colesevelam hydrochloride added to background metformin therapy in patients with type 2 diabetes mellitus: a pooled analysis from 3 clinical studies

OBJECTIVE

To evaluate the glucose- and lipid-altering efficacy of colesevelam hydrochloride (HCl) when added to background metformin therapy in patients with inadequately controlled type 2 diabetes mellitus (T2DM).

METHODS

This post hoc analysis included patients with T2DM from 3 randomized, double-blind, placebo-controlled pivotal studies who received metformin as part of their background antidiabetes therapy. In the pivotal studies, patients with T2DM were randomly assigned to receive colesevelam HCl (3.75 g/d) or placebo added to existing metformin (26 weeks), sulfonylurea (26 weeks), or insulin (16 weeks) monotherapy or combination therapy, wherein the combination therapies may have included metformin.

RESULTS

In this pooled analysis of 696 patients with T2DM who were receiving metformin monotherapy or metformin combined with other antidiabetes therapies, 355 were randomly assigned to receive colesevelam HCl and 341 to receive placebo. In comparison with placebo, colesevelam HCl significantly reduced hemoglobin A1c (A1C) and fasting plasma glucose (mean treatment difference: -0.50% and -15.7 mg/dL, respectively; P<.001 for both), as well as significantly reduced levels of low-density lipoprotein cholesterol (LDL-C; mean treatment difference: -16.5%), total cholesterol (TC; -5.8%), non-high-density lipoprotein cholesterol (non-HDL-C; -8.2%), and apolipoprotein (apo) B (-7.6%) (P<.0001 for all). Median triglyceride levels were increased with colesevelam HCl (median treatment difference: +12.8%; P<.0001). In comparison with placebo, colesevelam HCl significantly increased apo A-I (mean treatment difference: +3.3%; P<.0001), whereas the mean increase in HDL-C with colesevelam HCl was not significant. Colesevelam HCl therapy was generally well tolerated.

CONCLUSION

When added to metformin-including therapy, colesevelam HCl significantly reduced A1C and fasting glucose, as well as levels of LDL-C, TC, non-HDL-C, and apo B in patients with inadequately controlled T2DM.

The combination of colesevelam with sitagliptin enhances glycemic control in diabetic ZDF rat model

Bile acid sequestrants have been shown to reduce glucose levels in patients with type 2 diabetes. We previously reported that the bile acid sequestrant colesevelam HCl (Welchol) (COL) induced the release of glucagon-like peptide (GLP)-1 and improved glycemic control in insulin-resistant rats. In the present study, we tested whether adding sitagliptin (Januvia) (SIT), which prolongs bioactive GLP-1 half life, to COL would further enhance glycemic control. Male Zucker diabetic fatty (ZDF) rats were assigned to four groups: diabetic model without treatment (the model), the model treated with 2% COL or 0.4% (120 mg/day) SIT alone, or with the combination (COL+SIT). After 4 wk of treatment, the glucose area under the curve (AUC) was reduced more in the COL+SIT than the COL although both groups showed decreased glucose AUC with increased AUC of bioactive GLP-1 (GLP-1A) compared with the model group. The above changes were not observed after 8 wk. Increasing the SIT dose by 50% (180 mg SIT/day) in the diet reduced the glucose AUC in the COL+SIT group even after 8 wk but still not in the SIT alone group compared with the model. It was noteworthy that, after 8 wk, insulin levels in the SIT group declined to levels similar to the model. Histological examination of the pancreatic β-cell islets showed that islet sizes were larger, proliferation enhanced, and cell apoptosis reduced in the COL+SIT but not the SIT alone group compared with the model. We hypothesize that the combination of COL with SIT extends the half life of COL-induced GLP-1A and benefits preservation of the islets that delay the development of diabetes and improve glycemic control. This study suggests that the combined therapy (COL+SIT) is more effective than either drug alone for reducing glucose levels in diabetes.

Long-term (52-78 weeks) treatment with colesevelam HCl added to metformin therapy in type 2 diabetes mellitus patients

OBJECTIVE

To evaluate the long-term safety, tolerability, and efficacy of colesevelam HCl (colesevelam) in type 2 diabetes mellitus patients receiving metformin monotherapy or metformin combination therapy.

METHODS

This post-hoc subgroup analysis examined data from type 2 diabetes mellitus patients aged 18 to 75 years with a hemoglobin A(1c) of 7.5% to 9.5%, who received metformin as part of their treatment via their participation in one of three randomized, double-blind base studies wherein colesevelam (3.75 g/day) or a placebo was added to existing metformin-, insulin-, or sulfonylurea-based treatment. After completing the base studies, the subjects who initially received blinded colesevelam (n = 196) or the placebo (n = 166) entered a 52-week extension study wherein they received open-label colesevelam (3.75 g/day).

RESULTS

This analysis describes the 362 patients receiving background metformin therapy who also received open-label colesevelam (3.75 g/day) during a 1-year extension study. From a safety perspective, hypoglycemia was reported by 11 patients (3.0%; none severe). Drug-related adverse events (AEs) occurred in 38 patients (10.5%). At least one serious AE occurred in 35 patients (9.7%), with only one being assessed by investigators as drug related (exacerbation of diverticulitis). Twenty-four patients (6.6%) discontinued open-label treatment because of an AE (10 due to a drug-related AE). Compared with baseline values obtained prior to the start of both the base and extension studies, colesevelam improved and maintained improvement in hemoglobin A(1c) and various lipid parameters.

CONCLUSION

This analysis found colesevelam to be generally safe and effective for long-term therapy in type 2 diabetes mellitus patients with inadequately controlled glucose while treated with metformin monotherapy or metformin combination therapy.

Diagnosis, prevention, and management of statin adverse effects and intolerance: proceedings of a Canadian Working Group Consensus Conference

While the proportion of patients with significant statin-associated adverse effects or intolerance is very low, the increasing use and broadening indications have led to a significant absolute number of such patients commonly referred to tertiary care facilities and specialists. This report provides a comprehensive overview of the evidence pertaining to a broad variety of statin-associated adverse effects followed by a consensus approach for the prevention, assessment, diagnosis, and management. The overview is intended both to provide clarification of the untoward effects of statins and to impart confidence in managing the most common issues in a fashion that avoids excessive ancillary testing and/or subspecialty referral except when truly necessary. The ultimate goal is to ensure that patients who warrant cardiovascular risk reduction can be treated optimally, safely, and confidently with statin medications or alternatives when warranted.

Colesevelam hydrochloride powder for oral suspension versus cholestyramine powder for oral suspension: comparison of acceptability and tolerability

OBJECTIVE

To compare tolerability of colesevelam hydrochloride powder versus a cholesterol-lowering equivalent dose of generic cholestyramine powder, each mixed in water, by means of the validated Bile Acid Sequestrant Acceptability (BASA) Scale.

METHODS

We conducted a randomized, single-blind, single-visit, single-site study, comparing doses of 2 different bile acid sequestrant powders for oral suspension that produce similar cholesterol lowering: colesevelam hydrochloride (3.75 g) and generic cholestyramine (12 g), each mixed in a transparent cup with tap water.

RESULTS

The study sample consisted of 42 participants-12 men and 30 women. The study subjects were non-Hispanic white (64%) or black (36%), with a mean age of 50 years and a mean body mass index of 32.2 kg/m2. The components of the BASA Scale included taste, texture, appearance, and mixability. Colesevelam hydrochloride and cholestyramine did not differ significantly when assessed by both the unweighted and the weighted global BASA Scale. Although study participants indicated that the colorless or whitish colesevelam hydrochloride powder tasted better (P<.0001), they thought that the orange-colored cholestyramine had a more appealing appearance (P<.0001). Regarding the potential for taking the drug "for the rest of your life," 71.4% of study participants rated taste as "very important," and 11.9% rated appearance as "very important."

CONCLUSION

Although study participants thought that the orange-colored generic cholestyramine powder had a better appearance, they also reported that colesevelam hydrochloride for oral suspension tasted better. A minority of study participants thought appearance was "very important"; a substantial majority thought taste was "very important" for potential long-term compliance.

Role of the intestinal bile acid transporters in bile acid and drug disposition

Membrane transporters expressed by the hepatocyte and enterocyte play critical roles in maintaining the enterohepatic circulation of bile acids, an effective recycling and conservation mechanism that largely restricts these potentially cytotoxic detergents to the intestinal and hepatobiliary compartments. In doing so, the hepatic and enterocyte transport systems ensure a continuous supply of bile acids to be used repeatedly during the digestion of multiple meals throughout the day. Absorption of bile acids from the intestinal lumen and export into the portal circulation is mediated by a series of transporters expressed on the enterocyte apical and basolateral membranes. The ileal apical sodium-dependent bile acid cotransporter (abbreviated ASBT; gene symbol, SLC10A2) is responsible for the initial uptake of bile acids across the enterocyte brush border membrane. The bile acids are then efficiently shuttled across the cell and exported across the basolateral membrane by the heteromeric Organic Solute Transporter, OSTα-OSTβ. This chapter briefly reviews the tissue expression, physiology, genetics, pathophysiology, and transport properties of the ASBT and OSTα-OSTβ. In addition, the chapter discusses the relationship between the intestinal bile acid transporters and drug metabolism, including development of ASBT inhibitors as novel hypocholesterolemic or hepatoprotective agents, prodrug targeting of the ASBT to increase oral bioavailability, and involvement of the intestinal bile acid transporters in drug absorption and drug-drug interactions.

Treatment of dyslipidemia in patients with type 2 diabetes

Type 2 diabetes is associated with significant cardiovascular morbidity and mortality. Although low-density lipoprotein cholesterol levels may be normal in patients with type 2 diabetes, insulin resistance drives a number of changes in lipid metabolism and lipoprotein composition that render low-density lipoprotein cholesterol and other lipoproteins more pathogenic than species found in patients without type 2 diabetes. Dyslipidemia, which affects almost 50% of patients with type 2 diabetes, is a cardiovascular risk factor characterized by elevated triglyceride levels, low high-density lipoprotein cholesterol levels, and a preponderance of small, dense, low-density lipoprotein particles. Early, aggressive pharmacological management is advocated to reduce low-density lipoprotein cholesterol levels, regardless of baseline levels. A number of lipid-lowering agents, including statins, fibrates, niacin, and bile acid sequestrants, are available to target normalization of the entire lipid profile. Despite use of combination and high-dose lipid-lowering agents, many patients with type 2 diabetes do not achieve lipid targets. This review outlines the characteristics and prevalence of dyslipidemia in patients with type 2 diabetes and discusses strategies that may reduce the risk of cardiovascular disease in this population.

Role of bile acid sequestrants in the treatment of type 2 diabetes

Cholestyramine is a first-generation bile acid sequestrant (BAS) and antihyperlipidemic agent that currently has limited use because of its relatively weak effect on lowering low density-lipoprotein (LDL)-cholesterol (C) and poor tolerability. The current first choice drugs for hyper-LDL-cholesterolemia are 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) because of their strong LDL-C lowering effects and efficacy in prevention of cardiovascular disease. However, after lowering the target levels of LDL-C in very high risk patients, combination therapy with statins and other antihyperlipidemic drugs may become more important for treatment of hyper-LDL-cholesterolemia. Second-generation BASs such as colesevelam and colestimide have a glucose-lowering effect and improved tolerance, which has led to re-evaluation of their utility in combination with statins or antidiabetic agents.

Gut hormones and the brain

The dialogue between gut hormone, bile acids, and the brain plays an important role in energy homeostasis and the onset of Type 2 diabetes mellitus (T2DM). The present review focuses on: (i) bile acid metabolism and the role of bile acids in the regulation of both glucose homeostasis and the control of hypercholesterolemia; (ii) the role of gut hormones in energy homeostasis; and (iii) translation of the pathophysiology of bile acids and gut hormones into clinical practice. Although definitive mechanisms of action of gut hormones and bile acids have not been elucidated completely, these concepts allow us to understand several pharmacological interventions in the treatment of T2DM. Results from further clinical studies with related therapies will help us determine the role of these treatments in the management of energy homeostasis.

The Bile Acid Sequestrant Acceptability scale validation study

AIMS

The primary objective of this study was to validate a novel Bile Acid Sequestrant Acceptability (BASA) Scale intended to assess the acceptability and/or tolerability of bile acid sequestrant (BAS) beverage preparations. A secondary objective was to assess the utility of weightings based on subjective clinical importance for the BASA scale individual components and its composite score.

METHODS

This was a randomised, single-blind, single site, controlled study of oral administration of 4 g of orange-flavoured generic cholestyramine powder, 12 g of orange-flavoured generic cholestyramine powder and an orange-flavoured sweetened control drink powder, each mixed with water.

RESULTS

The study sample included 42 subjects; 26 men and 16 women. Participants were non-Hispanic white (76.2%) or black/African American (23.8%), with a mean age of 51.4 years and body mass index of 30.1 kg/m(2). The components of the BASA scale were taste, texture, appearance and mixability; the possible total BASA scores ranged being 4-20; the higher the BASA scale score, the better the acceptability/tolerability. Composite BASA scale scores were significantly lower for the 4 g (mean BASA score = 10.3) and 12 g (mean BASA score = 9.4) cholestyramine compared with the control drink powder (mean BASA score = 16.7) (p < 0.001). BASA scale scores did not significantly differ between the 4 and 12 g of cholestyramine. (p = 0.215). Weighting of the components did not materially alter the results. Findings for the individual components of the BASA scale were similar to the composite values.

CONCLUSION

The BASA scale effectively distinguished between an orange-flavoured BAS powder and a commercial orange-flavour control powder.

Combination drug-diet therapies for dyslipidemia

Expense, high drug dose, and low compliance to strict dietary therapies are current issues surrounding modern drug- and diet-based lipid-lowering approaches. Furthermore, variable patient outcomes and suboptimal response to both drug and diet therapies are increasingly evident. Therefore, the question arises as to whether more emphasis should be placed on combination diet/drug therapies to reduce cholesterol levels in patients who respond suboptimally to diet and drug monotherapies. Although considerable research has explored multidrug combination therapies, combination drug/diet therapies receive less attention. However, combined drug/diet approaches may reduce the number of drug prescriptions, the progressive increase in "optimal" drug dosage, and costs associated with pharmaceutical disease management. Future research priorities in drug/diet therapeutic approaches should not only emphasize the discovery of novel combinations but also should address potential safety issues prior to wide-scale acceptance in clinical practice. Accordingly, this review will assess current limitations associated with both drug and diet lipid-lowering therapies and explore the potential of combination drug/diet therapies in the treatment of dyslipidemia.

Cholestyramine reverses hyperglycemia and enhances glucose-stimulated glucagon-like peptide 1 release in Zucker diabetic fatty rats

Bile acid sequestrants (BAS) have shown antidiabetic effects in both humans and animals but the underlying mechanism is not clear. In the present study, we evaluated cholestyramine in Zucker diabetic fatty (ZDF) rats. Although control ZDF rats had continuous increases in blood glucose and hemoglobin A1c (HbA1c) and serum glucose and a decrease in serum insulin throughout a 5-week study, the cholestyramine-treated ZDF rats showed a dose-dependent decrease and normalization in serum glucose and HbA1c. An oral glucose tolerance test showed a significant increase in glucose-stimulated glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and insulin release in rats treated with cholestyramine. Quantitative analysis of gene expression indicated that cholestyramine treatment decreased farnesoid X receptor (FXR) activity in the liver and the intestine without liver X receptor (LXR) activation in the liver. Moreover, a combination of an FXR agonist with cholestyramine did not reduce the antihyperglycemic effect over cholestyramine alone, suggesting that the FXR-small heterodimer partner-LXR pathway was not required for the glycemic effects of cholestyramine. In summary, our results demonstrated that cholestyramine could completely reverse hyperglycemia in ZDF rats through improvements in insulin sensitivity and pancreatic beta-cell function. Enhancement in GLP-1 and PYY secretion is an important mechanism for BAS-mediated antidiabetic efficacy.

Colestilan monotherapy significantly improves glycaemic control and LDL cholesterol levels in patients with type 2 diabetes: a randomized double-blind placebo-controlled study

AIM

To evaluate the plasma glucose-reducing activity and safety of colestilan, a bile acid sequestrant, in patients with type 2 diabetes.

METHODS

Patients with fasting plasma glucose (FPG) 7.2-11.1 mmol/l and HbA (1c)> or =7.0% were randomly allocated in double-blind manner to receive colestilan or placebo therapy for 12 weeks.

RESULTS

A total of 183 patients entered the double-blind treatment phase. At 12 weeks, colestilan significantly reduced HbA (1c) and FPG vs. placebo by 0.9% and 1.2 mmol/l respectively (both p < 0.001). A significant (p < 0.001) 22.5% reduction of LDL cholesterol was also observed in the 172 patients evaluated (colestilan group: n = 86; placebo group: n = 86). However, no significant reduction of fasting insulin was observed (p = 0.087). No incidence of hypoglycaemia was reported in this study.

CONCLUSION

Colestilan improved glycaemic control and reduced LDL cholesterol levels in patients with type 2 diabetes.

Characterization of cardiovascular outcomes in a type 2 diabetes glucose supply and insulin demand model

BACKGROUND

The nonsignificant reduction in macrovascular outcomes observed in Action to Control Cardiovascular Risk in Diabetes; Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; and the Veterans Affairs Diabetes Trial have collectively created uncertainty with respect toward the proper extent of blood glucose reduction and also the optimal therapeutic choice to attain the reduction. In the article entitled "Glucose Supply and Insulin Demand Dynamics of Antidiabetic Agents" in this issue of Journal of Diabetes Science and Technology, we presented data for a pharmacokinetic/pharmacodynamic model that characterizes the effect of conventional antidiabetic therapies on the glucose supply and insulin demand dynamic. Here, it is our objective to test the hypothesis that, in conjunction with hemoglobin A1c (HbA1c), patients managed on the glucose supply side of the model would have fewer cardiovascular events versus those managed on the insulin demand side.

METHODS

To test this hypothesis, the electronic medical records of a group model health maintenance organization were queried to compile a population of patients meeting the following inclusion criteria: (1) type 2 diabetes mellitus (T2DM), (2) known date of T2DM diagnosis; (3) ICD-9 or CPT code identification and chart review confirmation of a first major cardiovascular event (myocardial infarction, coronary artery bypass graft, or angioplasty),(4) five years of continuous eligibility, and (5) on antidiabetic therapy at the beginning of the 5-year observation period. These patients were subsequently matched (1:1) to T2DM patients meeting the same criteria who had not experienced an event and were analyzed for differences in glucose control (HbA1C), the glucose supply:insulin demand dynamic (SD ratio), and categorical combinations of both parameters.

RESULTS

Fifty cardiovascular event patients met inclusion criteria and were matched to controls. No difference was observed for the average HbA1c or SD ratio between patients experiencing an event and controls (7.5 +/- 1.0% versus 7.3 +/- 0.9%, p = .275, and 1.2 +/- 0.3 versus 1.3 +/- 0.3, p = .205, respectively). Likewise, for categorical representations, there were no differences in event rate at the pre-identified breakpoints (HbA1c >or=7% versus <7%; 72% versus 64%, p = .391, and SD ratio >or=1 versus <1; 68% versus 76%, p = .373, >or=1.25 versus <1.25; 42% versus 56%, p = .161, >or=1.5 versus <1.5; 22% versus 30%, p = .362, respectively). Analyzing the combined effect of glucose control and the SD dynamic, patients managed at higher glucose values and on the insulin demand side of the model (HbA1c >or=7% and SD ratio <1.25) tended to have greater cardiovascular risk than those managed at an HbA1c <7%, or HbA1c >or=7% with an SD ratio >or=1.25 (61% versus 39%; p = .096).

CONCLUSION

Independently, more aggressive HbA1c reduction and higher SD ratio values were not independently associated with a reduction in cardiovascular outcomes. Combining the parameters, it would appear that patients managed at higher glucose values and on the insulin demand side of the model may have increased cardiovascular risk. Based on these findings, it is pertinent to conduct subsequent works to refine SD ratio estimates and apply the model to larger, long-term T2DM cardiovascular outcome trials. J Diabetes Sci Technol 2010;4(2):382-390.

Colesevelam improves insulin resistance in a diet-induced obesity (F-DIO) rat model by increasing the release of GLP-1

Bile acid sequestrants have been shown to lower glucose levels in patients with type 2 diabetes. To investigate how colesevelam (CL) HCl improves hyperglycemia, studies were conducted in diet-induced obesity (F-DIO) rats, which develop insulin resistance when fed a high-energy (high fat/high sucrose) diet (HE). The rats were fed HE; HE + 2% CL; HE + 0.02% SC-435 (SC), an apical sodium-dependent bile acid transporter inhibitor; and regular chow (controls). After 4 wk of treatment, both in the HE group and the SC + HE group, plasma glucose and insulin levels remained elevated compared with baseline values throughout an oral glucose tolerance test (OGTT). In contrast, in the CL + HE group, plasma glucose levels returned to baseline by the end of the test, and insulin peaked in 15-30 min and then returned to baseline. CL induced release of glucagon-like peptide-1 (GLP-1) because the area under the curve of plasma total GLP-1 in the CL + HE group was significantly greater than in the HE group during the OGTT. Bile acid concentrations in the portal blood did not decrease in the HE group but declined significantly both in the CL + HE and SC + HE groups with reduced farnesoid X receptor activation compared with controls. We concluded that CL reduces plasma glucose levels by improving insulin resistance in this rat model. It is unlikely that the improvement is attributable to decreased bile acid flux to the liver but is likely secondary to induced GLP-1 secretion, which improves insulin release.