Drug treatment of lipid disorders

Fenofibrate increases the L-arginine:ADMA ratio by increase of L-arginine concentration but has no effect on ADMA concentration

Asymmetric dimethylarginine (ADMA), a guanidino-substituted analogue of L-arginine, is a potent endogenous competitive inhibitor of the endothelial nitric oxide synthase and therefore a potentially atherogenic amino acid. Hyperlipidemia and hyperhomocysteinemia have both been reported to be associated with elevated ADMA concentrations. Therefore, we investigated the influence of micronized fenofibrate (200 mg/day, 6 week treatment) on the L-arginine:ADMA ratio in 25 hypertriglyceridemic men. ADMA was neither associated to serum triglycerides, serum cholesterol, LDL-cholesterol or HDL-cholesterol or plasma total homocysteine at baseline. Treatment with fenofibrate did not alter plasma ADMA level, in contrast to serum triglycerides which were significantly lowered and plasma total homocysteine which was significantly increased. In addition, serum L-arginine levels significantly increased, leading to a higher L-arginine:ADMA ratio after treatment. The null effect of fenofibrate on plasma ADMA levels is in line with reported effects of other lipid-lowering agents (HMG-CoA-reductase inhibitors), but fenofibrate treatment elevated the plasma L-arginine:ADMA ratio, suggesting an improvement of endogenous NO formation and endothelial function. The results do not support the view that in vivo ADMA metabolism itself is directly influenced by cholesterol or homocysteine.

Safety of rosuvastatin

The safety and tolerability of rosuvastatin were assessed (as of August 2003) using data from 12,400 patients who received 5 to 40 mg of rosuvastatin in a multinational phase II/III program, which represented 12,212 patient-years of continuous exposure to rosuvastatin. An integrated database was used to examine adverse events and laboratory data. In placebo-controlled trials, adverse events, irrespective of causality assessment, occurred in 57.4% of patients who received 5 to 40 mg of rosuvastatin (n = 744) and 56.8% of patients who received placebo (n = 382). In fixed-dose trials with comparator statins, 5 to 40 mg of rosuvastatin showed an adverse event profile similar to those for 10 to 80 mg of atorvastatin, 10 to 80 mg of simvastatin, and 10 to 40 mg of pravastatin. Clinically significant elevations in alanine aminotransferase (>3 times the upper limit of normal) and creatine kinase (>10 times the upper limit of normal) were uncommon (<or=0.2%) in the groups that received rosuvastatin and comparator statins. Myopathy (creatine kinase >10 times the upper limit of normal with muscle symptoms) that was possibly related to treatment occurred in <or=0.03% of patients who took rosuvastatin at doses <or=40 mg. A positive finding of proteinuria with dipstick testing at rosuvastatin doses <or=40 mg was comparable to that seen with other statins, and the development of proteinuria was not predictive of acute or progressive renal disease. No deaths in the program were attributed to rosuvastatin, and no rhabdomyolysis occurred in patients who received 5 to 40 mg of rosuvastatin. Rosuvastatin was well tolerated by a broad range of patients who had dyslipidemia, and its safety profile was similar to those of the comparator statins investigated in this extensive clinical program.

Fibrates in the metabolic syndrome and in diabetes

There is increasing evidence that fibrates can reduce coronary artery disease. This finding seems to be particularly the case inpatients with the metabolic syndrome or with diabetes. Their beneficial effects can be explained partly by their effects on lipoproteins,but these effects may also result from some of their nonlipid pleotropic effects. Clinical trials are still needed to determine the potential role played by such pleotropic actions.

HMG-CoA reductase inhibitors prevent bone loss in patients with Type 2 diabetes mellitus

AIMS

It has been reported that 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors increase bone mineral density (BMD) in vivo. We investigated the effect of HMG-CoA reductase inhibitors on BMD in patients with Type 2 diabetes mellitus.

PATIENTS AND METHODS

We selected 122 patients with Type 2 diabetes, who were not taking active vitamin D preparations. Their mean age was 67.3 +/- 9.2 years. They were divided into a control group (n=63) without HMG-CoA reductase inhibitor therapy and an HMG-CoA group (n=59) who were treated with these drugs. The BMD of the distal one-third of the radius was measured by dual-energy X-ray adsorptiometry at baseline and after 2 years.

RESULTS

There were no significant differences between the control and HMG-CoA groups at baseline with respect to age, gender, body mass index, duration of diabetes, haemoglobin A1c, fasting plasma glucose, adjusted calcium, serum phosphorus, alkaline phosphatase, albumin excretion rate and radial BMD. However, there was a significantly smaller annual decrease of the radial BMD in the HMG-CoA group. Multiple regression analysis with a forward elimination procedure revealed a positive correlation of the radial BMD Z-score with body mass index, while there was a negative correlation with alkaline phosphatase and albumin excretion rate. In addition, the annual rate of change of the radial BMD showed a positive correlation with HMG-CoA reductase inhibitor therapy.

CONCLUSIONS

These findings suggest that HMG-CoA reductase inhibitors may prevent bone loss in patients with Type 2 diabetes.

Cholesterol in neurologic disorders of the elderly: stroke and Alzheimer’s disease

Mechanisms for the regulation of intracellular cholesterol levels in various types of brain and vascular cells are of considerable importance in our understanding of the pathogenesis of a variety of diseases, particularly atherosclerosis and Alzheimer's disease (AD). It is increasingly clear that conversion of brain cholesterol into 24-hydroxycholesterol and its subsequent release into the periphery is important for the maintenance of brain cholesterol homeostasis. Recent studies have shown elevated plasma concentrations of 24-hydroxycholesterol in patients with AD and vascular dementia, suggesting increased brain cholesterol turnover during neurodegeneration. The oxygenases involved in the degradation and excretion of cholesterol, including the cholesterol 24-hydroxylase and the 27-hydroxylase, are enzymes of the cytochrome P-450 family. This review focuses on the newly recognized importance of cholesterol and its oxygenated metabolites in the pathogenesis of ischemic stroke and AD. The reduction in stroke and AD risk in patients treated with cholesterol-lowering statins is also discussed.

Efficacy and safety of ezetimibe coadministered with statins: randomised, placebo-controlled, blinded experience in 2382 patients with primary hypercholesterolemia

We assessed pooled safety and lipid-regulating efficacy data from four similarly designed trials of ezetimibe coadministered with statins in 2382 patients with primary hypercholesterolemia. Patients were randomised to one of the following double-blind treatments for 12 weeks: placebo; ezetimibe 10 mg; statin; or statin + ezetimibe. Statin doses tested were 10, 20, 40 mg/day (atorvastatin, simvastatin, pravastatin or lovastatin) or 80 mg/day (atorvastatin, simvastatin). Treatment with ezetimibe + statin led to significantly greater reductions in low-density lipoprotein cholesterol (LDL-C), total cholesterol, triglycerides, non-high-density lipoprotein cholesterol (non-HDL-C), apolipoprotein B and increases in HDL-C, compared to statin alone. At each statin dose, treatment with ezetimibe + statin led to a greater LDL-C reduction compared to the next highest statin monotherapy dose. Ezetimibe + statin had a safety profile similar to statin monotherapy. Coadministration of ezetimibe + statin offers a well-tolerated, highly efficacious new treatment strategy for patients with hypercholesterolemia.

Prevention and treatment of erectile dysfunction using lifestyle changes and dietary supplements: what works and what is worthless, part I

Clinicians working in urology should adhere to the same guidelines that are observed in cardiovascular medicine when dealing with a patient with ED. A golden opportunity exists to discuss lifestyle changes with any man with or concerned about ED. Providing heart-healthy recommendations to men with minimal to extensive ED may produce a twofold impact: (1) patients may be able to affect the future extent of their disease, and (2) patients may become healthier overall. Patients following a heart-healthy lifestyle after a diagnosis of ED or to prevent ED should enjoy increased quality or quantity of life. The time is more than ripe for patients to understand that heart health is tantamount to erectile health.

Niacin in HIV-infected individuals with hyperlipidemia receiving potent antiretroviral therapy

BACKGROUND

Extended release (ER)-niacin therapy, which has been associated with reduced glucose tolerance in human immunodeficiency virus (HIV)-seronegative individuals, has not been evaluated in the HIV-infected population.

METHODS

This open, prospective trial evaluated the safety and efficacy of ER-niacin therapy for antiretroviral therapy-associated dyslipidemia. Fourteen individuals received ER-niacin at maximum doses of 2000 mg per day for 14 weeks.

RESULTS

Significant reductions in serum levels of triglycerides (P=.02), total cholesterol (P=.005), and non-HDL cholesterol (P=.04) were seen after ER-niacin therapy. Seven of 11 subjects were glucose intolerant after ER-niacin therapy; for 3 of these subjects, this was a new finding. Beta-cell sensitivity to basal glucose levels increased significantly without concomitant increase in overall glucose disposition indices. The values for the homeostasis model of insulin resistance index increased significantly (P=.005).

CONCLUSION

ER-niacin's role in the treatment of antiretroviral therapy-associated dyslipidemia requires further evaluation, but the results of this pilot study indicate that it is safe and tolerated and provides a valuable treatment option.

HPLC-UV method development and validation for 16-dehydropregnenolone, a novel oral hypolipidaemic agent, in rat biological matrices for application to pharmacokinetic studies

An accurate and precise HPLC assay has been developed and validated for determination of dehydropregnenolone (DHP) in rat plasma, bile, urine and feces. Separation was achieved using a C-18 reversed phase column with a mobile phase comprising of acetonitrile and deionized water (55:45% v/v) using a UV detector, set at a wavelength of 248 nm. The method, applicable to 200-microl plasma, bile and urine, involved double extraction of the samples with n-hexane. The sample clean up for feces involved single extraction of 50 mg of sample with 3 ml of acetonitrile. The method was sensitive with a limit of quantitation of 20 ng/ml in all the matrices and absolute recovery >92%. Precision and accuracy were within the acceptable limits, as indicated by relative standard deviation varying from 4.7 to 11.2% and bias values ranging from 1.8 to 8.8%. Moreover, DHP was stable in plasma, bile and urine up to 90 days of storage at -60 degrees C and after being subjected to three freeze-thaw cycles. The method was applied to generate the pharmacokinetics of DHP in rats after oral and intravenous administration.

Management of Dyslipidaemia in HIV-Infected Patients Receiving Antiretroviral Therapy

Dyslipidaemia associated with the treatment of HIV infection, particularly with the use of protease inhibitors (PIs), can raise cholesterol and triglyceride (TG) levels to the thresholds indicated for intervention. Recent evidence from epidemiological studies has shown that there are correlations between antiretroviral drug use and increased risks for, and incidences of, cardiovascular disease, including myocardial infarction and coronary heart disease. The primary goals of dyslipidaemia therapy for HIV patients are reductions of both low-density lipoprotein cholesterol (LDL-C) and markedly elevated TG levels. Dietary strategies and exercise programs may be tried, although these have shown inconsistent results. The two options for drug therapy are switching anti-retroviral agents and using lipid-lowering drugs. Each approach is associated with advantages and limitations, and the need to maintain viral suppression must be balanced with the need to treat abnormal lipid levels. Most drug switches replace the PI component with drugs from another antiretroviral class. Selection of drug therapy for lipid lowering depends on the type of dyslipidaemia predominating and the potential for drug interactions. The use of the statins pravastatin and atorvastatin is recommended for the treatment of patients with elevated LDL-C levels and gemfibrozil or fenofibrate for patients with elevated TG concentrations. Development of new PIs with more favourable effects on the lipid profile should be of benefit.

Long-term safety and tolerability profile of ezetimibe and atorvastatin coadministration therapy in patients with primary hypercholesterolaemia

Long-term safety and tolerability of ezetimibe plus atorvastatin (EZE + ATV) coadministration therapy were compared to those of ATV monotherapy in patients with primary hypercholesterolaemia. Upon completion of a 12 week randomised, double-blind, placebo-controlled study comparing EZE 10 mg; ATV 10, 20, 40 or 80 mg; EZE + ATV 10, 20, 40 or 80 mg or placebo, 246 patients were enrolled in a 12-month extension, with reassignment to double-blind EZE 10 mg (n = 201) or matching placebo (n = 45) coadministered daily with open-label ATV 10 mg. At intervals of 6 weeks, patients not at National Cholesterol Education Program Adult Treatment Panel II LDL-C goals were titrated to the next higher ATV dose. Safety evaluations included adverse event (AE) reports and laboratory test results. EZE + ATV and ATV monotherapy groups were similar with regard to incidence of all AEs (71 vs. 67%), treatment-related AEs (22 vs. 27%) and discontinuations due to AEs (9 vs. 7%) or treatment-related AEs (6 vs. 7%), respectively. Neither clinically significant elevations in hepatic transaminases or creatine kinase nor any cases of myopathy or rhabdomyolysis were observed in either group during the extension study. After 6 weeks, EZE + ATV 10mg produced greater reductions in low-density lipoprotein cholesterol (LDL-C; -53 vs. -37%), total cholesterol (TC; -38.8 vs. -26.0%) and triglycerides (TG; -28 vs. -12%) and similar increases in high-density lipoprotein cholesterol (4.6 vs. 4.5%) compared to ATV 10 mg, respectively, and these changes were maintained and significant at 1 year (p < 0.01 for LDL-C, TC and TG). More EZE + ATV patients achieved LDL-C goal than ATV patients at study endpoint (91 vs. 78%, respectively; p = 0.02). Thus, the coadministration of EZE + ATV for 12 months was well tolerated and more efficacious than ATV monotherapy.

Improving lipid management--to titrate, combine or switch

Despite the benefits of statin therapy, cholesterol management remains suboptimal and many patients do not achieve their recommended low-density lipoprotein cholesterol (LDL-C) goals. The use of insufficient doses, limited drug effectiveness and poor patient compliance may contribute to the treatment gap. Options for improving lipid management include dose titration, combination therapy or prescribing a more efficacious statin. LDL-C reductions are generally modest when patients' current statin dose is titrated, and there may be an increased potential for adverse effects. Combining statin therapy with another lipid-modifying agent can provide additional LDL-C reductions, but cost, tolerability and compliance should be considered. In general, switching to a more efficacious statin is a cost-effective way of enabling more patients to achieve recommended targets without increasing dosages. When considering the options available, physicians should balance efficacy, cost and safety to enable more patients to attain LDL-C goals and achieve greater therapeutic gain from statin treatment.

Simulating titration to goal clinical trials with statins

Many countries have local guidelines on the management of subjects' lipid levels with and without pharmaceutical intervention. The statin class of drugs is the preferred class for reducing low density lipoprotein cholesterol (LDL-C). Different statins have different potencies and different dose ranges. It is of interest to simulate clinical trials in which subjects are titrated through the dose ranges of various statins in accordance with local guidelines, in order to estimate the proportion of subjects who reach treatment goal of LDL-C at any particular dose of any particular statin.

Decreased circulating Fas ligand in patients with familial combined hyperlipidemia or carotid atherosclerosis: normalization by atorvastatin

OBJECTIVES

We sought to study whether patients with familial combined hyperlipidemia (FCH) or carotid atherosclerosis have modified circulating solubilized Fas ligand (sFasL) levels, as well as the potential modifications by atorvastatin. We also examined the effect of atorvastatin on FasL expression and sFasL release in cytokine-stimulated cultured human endothelial cells (ECs).

BACKGROUND

In normal situations, FasL is expressed in most cells, including ECs. Proinflammatory stimuli can downregulate its expression in ECs and facilitate the vascular infiltration of inflammatory cells.

METHODS

We have measured sFasL plasma levels (by ELISA) in 58 patients with FCH, 14 normocholesterolemic patients with carotid atherosclerosis, and 15 healthy volunteers. We analyzed FasL expression (by Western blot analysis) and sFasL release in cultured ECs stimulated with tumor necrosis factor (TNF)-alpha.

RESULTS

Solubilized FasL levels were decreased in hyperlipidemic patients (49 pg/ml), as compared with healthy volunteers (123 pg/ml, p < 0.0001). Patients were randomized to atorvastatin (n = 28) or bezafibrate (n = 30) during 12 months. Atorvastatin treatment increased sFasL concentrations (111 pg/ml, p < 0.0001), reaching normal values. However, treatment with bezafibrate only marginally affected sFasL (85 pg/ml, p < 0.05). Solubilized FasL was also diminished in patients with carotid atherosclerosis (39 pg/ml), and intensive treatment with atorvastatin normalized sFasL levels (90 pg/ml, p = 0.02). Finally, atorvastatin prevented the diminution of FasL expression and sFasL release elicited by TNF-alpha in cultured ECs.

CONCLUSIONS

Patients with FCH or carotid atherosclerosis have decreased circulating sFasL levels, probably indicating endothelial dysfunction, but treatment with atorvastatin restored normal blood levels. These data provide a novel effect of atorvastatin and add support for the well-known anti-inflammatory properties of statins.

Genetically defined hyperlipidemia

The unraveling of genetic defects associated with disorders in lipid metabolism has contributed to the understanding of lipoprotein metabolism and the pathophysiological consequences of a particular mutation. The translation, however, of a single genetic defect into the individual's risk of cardiovascular disease and subsequent treatment strategies is an extremely complex issue that involves the identification of multiple additional determinants, including genetic, metabolic and environmental factors. The discovery of these factors, including genetic determinants of drug efficacy, provides insight into the interaction between regulatory systems traditionally thought to be unrelated and may, in the future, lead to a more complete diagnostic and therapeutic appreciation of the individual patient.

Ezetimibe: a novel option for lowering cholesterol

Elevated low-density lipoprotein (LDL)-cholesterol is associated with a significantly increased risk of coronary heart disease but lowering LDL-cholesterol to levels established in current National Cholesterol Education Program (NCEP) guidelines provides significant risk reduction. Nevertheless, many patients receiving lipid-lowering therapy, particularly those at highest coronary heart disease risk, do not reach LDL-cholesterol goals with their current medications. Ezetimibe (Zetia, Merck Schering-Plough) is the first of a new class of lipid-lowering drugs known as cholesterol absorption inhibitors. Ezetimibe has a favorable pharmacokinetic profile, which allows it to be administered once daily and to be given in conjunction with statins. In a series of randomized, controlled, multicenter studies, ezetimibe produced significant improvements in levels of LDL-cholesterol and other lipid parameters when used as monotherapy, with a safety profile comparable with that of placebo. Furthermore, coadministration of ezetimibe with a statin (simvastatin, atorvastatin, lovastatin, or pravastatin) was more effective than statin monotherapy in lowering LDL-cholesterol and improving other lipid parameters. Moreover, coadministration of ezetimibe with a statin allowed a greater percentage of patients to achieve treatment goals established in NCEP guidelines. The safety and side-effect profile of ezetimibe plus statin coadministration therapy was generally comparable with that of statin monotherapy. These studies establish ezetimibe as an effective lipid-lowering agent, which will likely be useful in the management of a broad range of patients with hypercholesterolemia. Ezetimibe can be used in conjunction with a statin at the beginning of therapy, or it can be added if patients do not achieve their LDL-cholesterol goal with statins alone.

Efficacy and safety of ezetimibe coadministered with simvastatin in patients with primary hypercholesterolemia: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To compare the efficacy and safety of 10 mg of ezetimibe coadministered with simvastatin with the safety and efficacy of simvastatin monotherapy for patients with hypercholesterolemia.

PATIENTS AND METHODS

This multicenter double-blind, placebo-controlled, factorial study enrolled 887 patients with hypercholesterolemia (low-density lipoprotein cholesterol [LDL-C], 145-250 mg/dL; triglycerides, < or = 350 mg/dL). Patients were randomized to 1 of 10 treatments--placebo, ezetimibe at 10 mg/d, simvastatin at 10, 20, 40, or 80 mg/d, or simvastatin at 10, 20, 40, or 80 mg/d plus ezetimibe at 10 mg/d for 12 weeks. The study began March 13, 2001, and ended January 8, 2002. The primary efficacy end point was the mean percent change in LDL-C levels from baseline to study end point (last available postbaseline LDL-C measurement) for the pooled ezetimibe/simvastatin group vs the pooled simvastatin monotherapy group.

RESULTS

Coadministration of ezetimibe/simvastatin was significantly (P<.001) more effective than simvastatin alone in reducing LDL-C levels for the pooled ezetimibe/simvastatin vs pooled simvastatin analysis and at each specific dose comparison. The decrease in LDL-C levels with coadministration of ezetimibe and the lowest dose of simvastatin, 10 mg, was similar to the decrease with the maximum dose of simvastatin, 80 mg. A significantly (P<.001) greater proportion of patients in the ezetimibe/simvastatin group achieved target LDL-C levels compared with those in the monotherapy group. Treatment with ezetimibe/simvastatin also led to greater reductions in total cholesterol, triglyceride, non-high-density lipoprotein cholesterol, and apolipoprotein B levels compared with simvastatin alone; both treatments increased high-density lipoprotein cholesterol levels similarly. The safety and tolerability profiles for the ezetimibe/simvastatin and monotherapy groups were similar.

CONCLUSION

Through dual inhibition of cholesterol absorption and synthesis, coadministration of ezetimibe/simvastatin offers a highly efficacious and well-tolerated lipid-lowering strategy for treating patients with primary hypercholesterolemia.

S-(2-(Acylamino)phenyl) 2,2-dimethylpropanethioates as CETP inhibitors

Studies on the relationship between the structure of the benzene moiety of S-(2-(acylamino)phenyl) 2,2-dimethylpropanethioates and CETP inhibitory activity were performed. Substituents on the benzene moiety influenced CETP inhibitory activity in a type and position dependent manner, and electron-withdrawing groups at the 4- or 5-position increased the activity. The most potent compound showed 50% inhibition of CETP activity in human plasma at a concentration of 2 microM.

Management of protease inhibitor-associated hyperlipidemia

Dyslipidemia, characterized by elevated serum levels of triglycerides and reduced levels of total cholesterol, low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol, has been recognized in patients with human immunodeficiency virus (HIV) infection. It is thought that elevated levels of circulating cytokines, such as tumor necrosis factor-alpha and interferon-alpha, may alter lipid metabolism in patients with HIV infection. Protease inhibitors, such as saquinavir, indinavir and ritonavir, have been found to decrease mortality and improve quality of life in patients with HIV infection. However, these drugs have been associated with a syndrome of fat redistribution, insulin resistance, and hyperlipidemia. Elevations in serum total cholesterol and triglyceride levels, along with dyslipidemia that typically occurs in patients with HIV infection, may predispose patients to complications such as premature atherosclerosis and pancreatitis. It has been estimated that hypercholesterolemia and hypertriglyceridemia occur in greater than 50% of protease inhibitor recipients after 2 years of therapy, and that the risk of developing hyperlipidemia increases with the duration of treatment with protease inhibitors. In general, treatment of hyperlipidemia should follow National Cholesterol Education Program guidelines; efforts should be made to modify/control coronary heart disease risk factors (i.e. smoking; hypertension; diabetes mellitus) and maximize lifestyle modifications, primarily dietary intervention and exercise, in these patients. Where indicated, treatment usually consists of either pravastatin or atorvastatin for patients with elevated serum levels of LDL-C and/or total cholesterol. Atorvastatin is more potent in lowering serum total cholesterol and triglycerides compared with other hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, but it is also associated with more drug interactions compared with pravastatin. Simvastatin and lovastatin are significantly metabolized by cytochrome P450 enzymes (CYP3A4) and are therefore not recommended for coadministration with protease inhibitors. A fibric acid derivative (gemfibrozil or fenofibrate) should be used in patients with primary hypertriglyceridemia. However, it must be kept in mind that protease inhibitors, such as nelfinavir and ritonavir, induce enzymes involved in the metabolism of the fibric acid derivatives and may, therefore, reduce the lipid-lowering activity of coadministered gemfibrozil or fenofibrate. In certain patients HMG-CoA reductase inhibitors may be used in combination with fibric acid derivatives but patients should be carefully monitored for liver and skeletal muscle toxicity. Select patients may experience improvements in serum lipid levels when their offending protease inhibitor(s) is/are exchanged for efavirenz, nevirapine, or abacavir; however each patient's virologic and immunologic status must be taken closely into consideration.

New drugs for the treatment of hypercholesterolaemia

Endogenous and exogenous pathways determine plasma levels of cholesterol and lipoproteins. Plasma cholesterol levels and coronary heart disease risk can be reduced pharmacologically by decreasing cholesterol synthesis, increasing its elimination and/or reducing its absorption from the intestine. The more profound knowledge about cholesterol homeostasis has allowed the development of several lipid-lowering drugs with different mechanisms of action, with the purpose of reducing both morbidity and mortality associated with coronary heart disease. Two new and more potent 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins), also called superstatins (rosuvastatin and pitavastatin), are being studied for their ability to improve lipid profiles. Rosuvastatin is a potent, hepato-selective and relatively hydrophilic statin with a low propensity for muscle toxicity and drug interactions. Pitavastatin is another statin with a high oral bioavailability and minimal propensity for cytochrome p450-mediated drug interactions. Rosuvastatin seems to be more potent than other available statins while pitavastatin presents with a similar potency to that of atorvastatin. Another promising approach for lowering total and low-density lipoprotein cholesterol levels is inhibition of cholesterol absorption. A wide variety of new agents with the capacity for inhibiting the intestinal cholesterol absorption is currently being investigated. Ezetimibe is a selective cholesterol absorption inhibitor whose clinical efficacy has been recently demonstrated both in monotherapy and in combination with other lipid-lowering drugs. Colesevelam, a new bile acid sequestrant, has shown a clinical efficacy similar to that of other resins, with minimal gastrointestinal side effects, improving tolerability and patient compliance. Other lipid-lowering drugs with the ability to act at the enterocyte level, such as avasimibe and implitapide, are currently being investigated in humans.

Current overview of statin-induced myopathy

Statins are an efficacious and well-tolerated class of lipid-altering agents that have been shown to reduce the risk of initial and recurrent cardiovascular events. However, cerivastatin was withdrawn from the world market because of its potential for severe myotoxic effects. Since the benefits of statin treatment outweigh the small risk of adverse events, statins remain the first-line therapy for lipid lowering and preventing atherosclerotic cardiovascular diseases. The risk of myopathy may be minimized with the appropriate choice of agent and by identifying patients at risk of myotoxic effects. Elderly or female patients, or those with concomitant medications or impaired metabolic processes, may be at increased risk and should be monitored closely. The risk of myopathy may also be inferred from the pharmacologic and pharmacokinetic properties of the statin used. Since myotoxic events are more frequent at higher doses, statins that are effective in reducing cholesterol levels and helping patients to reach target levels at start doses may be useful. The lipophilicity of a statin and its potential for drug-drug interactions may also help to determine the likelihood of muscular effects. Drug-drug interactions may be avoided by selecting a statin that does not share the same metabolic pathway.

A novel class of apical sodium-dependent bile acid transporter inhibitors: the amphiphilic 4-oxo-1-phenyl-1,4-dihydroquinoline derivatives

A series of 4-oxo-1-phenyl-1,4-dihydroquinolines possessing a linker and an ammonio moiety were synthesized and found to inhibit the apical sodium-dependent bile acid transporter (ASBT). The potency of ASBT inhibition varied with the position and length of the linking tether. Compound 21e effectively lowered the total serum cholesterol levels in hamsters.

The role of fibrates in managing hyperlipidemia: Mechanisms of action and clinical efficacy

At a time when the lipid management guidelines give more and more emphasis to the identification and treatment of high-risk patients with the metabolic syndrome and diabetes, there is an obvious need to balance the known effects of low-density lipoprotein (LDL) lowering with the new evidence of clinical efficacy derived from the adjustment of high-density lipoprotein (HDL) and triglyceride levels. Whereas the statins remain the drug of choice for patients who need to reach the LDL goal, fibrate therapy may represent the best intervention for subjects with atherogenic dyslipidemia and an LDL already close to goal. In addition, the concomitant use of fibrates may significantly reduce cardiovascular risk in patients whose LDL is controlled by statin therapy. In this review, we evaluate the pharmacologic properties of the fibrate drugs, with particular attention to the effects of peroxisome proliferator activated receptor a activation in the control of dyslipidemia as well as in the attenuation of arterial inflammation. Clinical trials of fibrates, such as the Helsinki Heart Study, Veterans Affairs High-density lipoprotein Intervention Trial, Diabetes Atherosclerosis Intervention Study, and Bezafibrate Infarction Prevention trial, have conjured up a scenario for the clinical utility of fibrates and their possible superiority to statins in the management of obese, insulin-resistant, and diabetic patients presenting with near-goal LDL and inappropriate HDL and triglyceride levels.

Obesity as the core of the metabolic syndrome and the management of coronary heart disease

The global burden of coronary heart disease (CHD) has led to the introduction of international guidelines to minimize the morbidity and mortality that result from this condition. These guidelines recognize the contribution of multiple risk factors to the development of CHD and advocate a multifaceted approach to treatment. Obesity, particularly visceral adiposity, contributes to the clustering of many other risk factors, such as hypertension, insulin resistance/type 2 diabetes and dyslipidemia, within individual patients. The molecular mechanisms underlying the metabolic abnormalities induced by visceral adiposity have yet to be fully elucidated; however, adipocytokines such as adiponectin, tumor necrosis factor-alpha and resistin seem to play an important role in this process. Obesity is a major modifiable CHD risk factor, and the benefits of weight loss are numerous, leading to improvements in several co-morbidities. Guidelines advocate lifestyle changes to correct excess bodyweight and improve the CHD risk factor profile. In addition, pharmacologic therapy is recommended for the management of other risk factors, such as hypertension and dyslipidemia, which may not be adequately controlled by lifestyle changes alone. Lowering low-density lipoprotein cholesterol (LDL-C) levels is the primary target for drug therapy for CHD prevention, and statins are first-line lipid-modifying therapy. The introduction of more efficacious statins with favorable effects on the lipid profile will optimize the control of dyslipidemia. Combining these new treatments with lifestyle changes and drug therapies for managing other CHD risk factors, as part of a multifaceted approach to treatment, will have benefits for CHD prevention.

Cholesterol-lowering properties of Ganoderma lucidum in vitro, ex vivo, and in hamsters and minipigs

INTRODUCTION

There has been renewed interest in mushroom medicinal properties. We studied cholesterol lowering properties of Ganoderma lucidum (Gl), a renowned medicinal species.

RESULTS

Organic fractions containing oxygenated lanosterol derivatives inhibited cholesterol synthesis in T9A4 hepatocytes. In hamsters, 5% Gl did not effect LDL; but decreased total cholesterol (TC) 9.8%, and HDL 11.2%. Gl (2.5 and 5%) had effects on several fecal neutral sterols and bile acids. Both Gl doses reduced hepatic microsomal ex-vivo HMG-CoA reductase activity. In minipigs, 2.5 Gl decreased TC, LDL- and HDL cholesterol 20, 27, and 18%, respectively (P < 0.05); increased fecal cholestanol and coprostanol; and decreased cholate.

CONCLUSIONS

Overall, Gl has potential to reduce LDL cholesterol in vivo through various mechanisms. Next steps are to: fully characterize bioactive components in lipid soluble/insoluble fractions; evaluate bioactivity of isolated fractions; and examine human cholesterol lowering properties. Innovative new cholesterol-lowering foods and medicines containing Gl are envisioned.

Inhibition of cytochrome P450 3A: relevant drug interactions in gastroenterology

Cytochrome P450 3A (CYP3A) is involved in biotransformation of more than half of all drugs currently available. Drug interactions by inhibition of CYP3A are of major interest in patients receiving combinations of drugs. Some interactions with CYP3A inhibitors also involve inhibition of the multidrug export pump, P-glycoprotein. An increasing number of adverse drug reactions might be avoided on the basis of knowledge about CYP3A substrates and inhibitors. This article summarizes some examples of such interactions relevant to gastroenterologists. Serious cases by coadministration of CYP3A inhibitors resulting in acute hepatitis, hypotension, rhabdomyolyis, torsade de pointes, sedation, or ergotism are presented: interactions with azole antifungals (ketoconazole, itraconazole, fluconazole), HIV protease inhibitors (ritonavir, indinavir, saquinavir, nelfinavir), macrolide antibiotics (clarithromycin, erythromycin), and grapefruit juice. In addition, 1 case is reported who presented the highest trough levels of the CYP3A substrate budesonide in serum ever measured. Practitioners have to be aware of the high potential of metabolic drug interactions when they prescribe a CYP3A inhibitor. It is wise to check carefully comedication in patients complaining of side effects with substrates of CYP3A.

Discovering modes of action for therapeutic compounds using a genome-wide screen of yeast heterozygotes

Modern medicine faces the challenge of developing safer and more effective therapies to treat human diseases. Many drugs currently in use were discovered without knowledge of their underlying molecular mechanisms. Understanding their biological targets and modes of action will be essential to design improved second-generation compounds. Here, we describe the use of a genome-wide pool of tagged heterozygotes to assess the cellular effects of 78 compounds in Saccharomyces cerevisiae. Specifically, lanosterol synthase in the sterol biosynthetic pathway was identified as a target of the antianginal drug molsidomine, which may explain its cholesterol-lowering effects. Further, the rRNA processing exosome was identified as a potential target of the cell growth inhibitor 5-fluorouracil. This genome-wide screen validated previously characterized targets or helped identify potentially new modes of action for over half of the compounds tested, providing proof of this principle for analyzing the modes of action of clinically relevant compounds.

Benefits and risks of simvastatin in patients with familial hypercholesterolaemia

Familial hypercholesterolaemia is a frequent, inherited, monogenic disorder, associated with accelerated development of atherosclerotic disease leading to coronary artery disease. Life expectancy of patients with familial hypercholesterolaemia is reduced by 15-30 years unless they are adequately treated with lipid-lowering therapy. Given the chronic nature of this disease, the selection of a therapeutic approach should be strongly based on its long-term safety and tolerability. The introduction of HMG-CoA reductase inhibitors has revolutionised the treatment of familial hypercholesterolaemia. Simvastatin 40-80 mg/day effectively reduces serum low density lipoprotein (LDL)-cholesterol levels. Furthermore, simvastatin reduces triglycerides and mildly raises high density lipoprotein-cholesterol levels. In addition to the hypolipidaemic effect, other potentially important effects, such as improvement of endothelial function and reduction of LDL oxidation and vascular inflammation, have been associated with HMG-CoA reductase inhibitor therapy. Simvastatin has also been shown to abolish the progression, and even facilitate the regression, of existing human atherosclerotic lesions. The good safety and tolerability profile of simvastatin is clearly highlighted by the low rate of therapy discontinuation observed in several population-based clinical trials. The most common adverse events leading to the discontinuation of therapy are gastrointestinal upset and headache. Asymptomatic elevations in liver transaminase levels and myopathy are uncommon. The overwhelming clinical evidence regarding the long-term use of HMG-CoA reductase inhibitor therapy in patients with familial hypercholesterolaemia together with the long-term safety data (particularly relating to simvastatin) provide support for the use of this drug as a first-line agent when pharmacological treatment is indicated. Early intervention with simvastatin treatment can be successfully implemented with favourable economic benefits.

Synthesis and Biological Evaluation of Quinuclidine Derivatives Incorporating Phenothiazine Moieties as Squalene Synthase Inhibitors

Squalene synthase inhibitors have the potential to be superior hypocholesterolemic agents. A series of quinuclidine derivatives incorporating phenothiazine systems was synthesized in order to investigate the effects of their structure on the inhibition of hamster liver microsomal enzyme. (+/-)-3-(10-Methyl-10H-phenothiazin-3-ylmethoxy)quinuclidine hydrochloride (19) was the most potent inhibitor in this series with an IC(50) value of 0.12 microM. Oral dosing of compound 19 to hamsters demonstrated effective reduction of both plasma total cholesterol levels and plasma triglyceride levels. Compound 19 showed a reduced tendency to elevate plasma transaminase levels, an indicator of hepatotoxicity. Enantiomerically pure (-)-19, YM-53546, was found to be more potent than the corresponding (+)-enantiomer.

The Role of Cholesterol and Statins in Alzheimer's Disease

OBJECTIVE:

To briefly discuss the impact of elevated total and low-density-lipoprotein cholesterol levels, as well as the potential relationship of hydroxymethylglutaryl coenzyme A reductase inhibitor (statin) use, on the development of Alzheimer's disease (AD).

DATA SOURCES:

Biomedical literature was accessed through MEDLINE and International Pharmaceutical Abstracts (1966–June 2003). The authors independently reviewed literature for possible inclusion in this article.

STUDY SELECTION AND DATA EXTRACTION:

Clinical studies were selected and reviewed from the data sources, with special emphasis on those dealing with statin use and AD.

DATA SYNTHESIS:

The impact of AD is significant, as it is rapidly becoming one of our country's most debilitating and costly diseases. Data from epidemiologic trials indicate that statins may have some protective effect against the development of AD. These trials also allude to theories regarding possible mechanisms of action for this use, data implicating possible superiority of one statin over another, and their lack in certain populations, specifically the very old elderly population.

CONCLUSIONS:

Preliminary evidence suggests that statins may offer a protective effect against the development of AD. However, review of the literature does not lend credence to the use of statins in the general nondemented population without hyperlipidemia. Potential confounding variables have not been considered in the majority of trials. Placebo-controlled clinical trials are ongoing and should yield more definitive results.

Cholesterol Management and the Reduction of Cardiovascular Risk

The increasing number of outcomes-based clinical trials addressing cardiovascular risk factor reduction using statin therapy has resulted in a substantial revision of the management of patients at risk for cardiovascular events. The clinical trials involve both primary and secondary preventive care. This review outlines the trials addressing primary and secondary prevention, detailing the more recently published studies, their place in risk-factor management, and their relationship to the National Cholesterol Education Program guidelines. Available data in elderly patients are reviewed, as are the adverse effects of the different statins and the statin drugs undergoing preliminary trials but not yet approved for general clinical use. The underuse of statin therapy is also addressed. Conclusions are drawn regarding the appropriate use of statin therapy in the contemporary primary and secondary preventive management of patients to reduce cardiovascular mortality and morbidity.

Substitution of Pioglitazone for Troglitazone in Patients with Type 2 Diabetes

OBJECTIVE

To evaluate the clinical utility of pioglitazone therapy in patients who previously received troglitazone.

METHODS

We undertook an observational study involving patients with type 2 diabetes, who were originally treated with troglitazone and subsequently converted to pioglitazone therapy. Drug efficacy was evaluated by comparing baseline hemoglobin A1c (HbA1c) levels, weight, blood pressure, and lipid profiles (during troglitazone treatment) with corresponding values 6 months after final pioglitazone dose titration. Drug safety was evaluated by review of hepatic enzyme levels and documented reports of side effects.

RESULTS

The study cohort consisted of 316 patients in whom pioglitazone therapy was initiated after they had received troglitazone for at least 1 year. Discontinuation of pioglitazone treatment subsequently occurred in 43 patients; in 7 additional patients, no follow-up occurred. We found no significant difference between baseline and follow-up mean HbA1c values. Aspartate aminotransferase levels did not significantly change after 6 months of pioglitazone therapy; however, alanine aminotransferase levels increased by a statistically significant 3.8 U/L (95% confidence interval, 2.6 to 4.9). Pioglitazone treatment was discontinued because of edema in 29 of the 309 evaluable patients (9.4%).

CONCLUSION

Pioglitazone was as effective as troglitazone in maintaining HbA1c levels. The hepatic safety of pioglitazone was also demonstrated.

Pharmacology and therapeutics of ezetimibe (SCH 58235), a cholesterol-absorption inhibitor

BACKGROUND

Ezetimibe is the first of a new class of antihyperlipidemic agents, the cholesterol-absorption inhibitors. It is indicated for monotherapy or in combination with 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors (statins) in patients with primary hypercholesterolemia, in combination with simvastatin or atorvastatin in patients with homozygous familial hypercholesterolemia, and as monotherapy in patients with homozygous familial sitosterolemia.

OBJECTIVE

This article reviews available data on the clinical pharmacology, clinical efficacy, and tolerability of ezetimibe.

METHODS

A literature review was conducted using the search terms ezetimibe and SCH 58235 to identify articles and abstracts indexed in MEDLINE and the Iowa Drug Information Service from 1966 to February 2003. The reference lists of the identified articles were reviewed for additional publications.

RESULTS

In adults, ezetimibe 10 mg PO given once daily has been reported to reduce intestinal cholesterol absorption by 54% from baseline in association with a compensatory increase in endogenous cholesterol synthesis. Within 2 weeks of its initiation, ezetimibe monotherapy produced a 17% to 20% reduction from baseline in low-density lipoprotein cholesterol (LDL-C); in combination with statins, ezetimibe produced a reduction in LDL-C of up to 40% over the same period. Based on studies performed to date, ezetimibe appears to be well tolerated, with a safety profile similar to that of placebo. Because ezetimibe is eliminated primarily by glucuronidation and not by cytochrome P450 (CYP) oxidation, it is subject to minimal drug interactions involving the CYP enzyme system.

CONCLUSIONS

Ezetimibe is an option for monotherapy in patients with mild hypercholesterolemia or in those requiring adjunctive drug therapy for reduction of LDL-C levels. It may be useful in patients at risk for adverse events (eg, liver toxicity, myopathy) from other hypocholesterolemic agents. Additive LDL-C-lowering effects of ezetimibe may allow use of lower doses of conventional agents (eg, statins, fibric acid derivatives, niacin) to achieve an equivalent effect, thereby reducing the potential for adverse events and drug interactions. However, because trials have lasted no longer than 12 weeks, the long-term effect of ezetimibe on cardiovascular morbidity and mortality remains to be determined.

Comparing myotoxic effects of squalene synthase inhibitor, T-91485, and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in human myocytes

TAK-475 is a squalene synthase inhibitor, rapidly metabolized to T-91485 in vivo. We investigated the myotoxicities of T-91485 and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in a human rhabdomyosarcoma cell line, RD, and in human skeletal myocytes. In differentiated RD cells, T-91485, atorvastatin (ATV) and simvastatin acid (SIM) inhibited cholesterol biosynthesis, with IC(50) values of 36, 2.8 and 3.8 nM, respectively. ATV and SIM decreased the intracellular ATP content, with IC(25) values (concentrations giving a 25% decrease in intracellular ATP content) of 0.61 and 0.44 microM, respectively. Although T-91485 potently inhibited cholesterol synthesis in RD cells, the IC(25) value exceeded 100 microM. In human skeletal myocytes, T-91485, ATV and SIM concentration-dependently inhibited cholesterol biosynthesis, with IC(50) values of 45, 8.6 and 8.4 nM, respectively. ATV and SIM decreased intracellular ATP content, with IC(25) values of 2.1 and 0.72 microM, respectively. Although T-91485 potently inhibited cholesterol synthesis, the IC(25) value exceeded 100 microM. Myotoxicity induced by ATV was prevented by mevalonate or geranylgeranyl-PP, but not by squalene in skeletal cells. Furthermore, T-91485 attenuated the myotoxicity of ATV. These findings suggest that TAK-475 and T-91485 may not only be far from myotoxic, they may also decrease statin-induced myotoxicity in lipid-lowering therapy.

Management of dyslipidemias in the age of statins

Evidence for the effectiveness of lipid-lowering therapy in reducing CHD risk continues to emerge. In primary prevention, clinical trials have demonstrated a benefit for middle-aged, high-risk men with high LDL cholesterol and, more recently, for men and women with "average" LDL and low HDL cholesterol. Although low HDL cholesterol, small dense LDL particles, elevated lipoprotein (a), elevated apolipoprotein B, and the dyslipidemia of the metabolic syndrome pose an increased in CHD risk in some patients, the risk reduction with lipid-lowering therapy has not been fully investigated. The CHD risk of isolated hypertriglyceridemia remains uncertain. Very high triglyceride levels, however, should be treated to prevent pancreatitis. A lipid-lowering diet and other appropriate lifestyle changes constitute safe advice for all patients with dyslipidemia. In initiating pharmacologic therapy, physicians should view potential risk reduction in the context of a patient's overall CHD risk. The selection of particular medications can be individualized, considering effectiveness evidence from clinical trials, lipid-lowering potency, adverse effects, drug interactions, costs, and patient preferences.

Pharmacokinetic drug interactions with nevirapine

Treatment of HIV infection is a multi-drug issue. Not only are there drugs for the treatment of HIV but also concomitant drugs for opportunistic infections, complications arising from the anti-retroviral therapy and other conditions related to a chronic disease. To have any understanding of drug-drug interactions in HIV treatment we need to appreciate the importance of key pharmacological areas including: 1) how each drug in a regimen is eliminated; 2) the potential for a drug to either induce or inhibit metabolic enzymes and/or transporters; 3) the therapeutic index of each drug. It is impossible to memorise all the possible drug-drug interactions in HIV, therefore understanding how drugs are metabolised/eliminated and the potential for a particular drug to modify the pharmacokinetics of another has predictive value even when substantive data are unavailable. NNRTIs interact with cytochrome P450 (CYP450) enzymes both as substrates and inducers. Because of the inductive effects caution must be exercised when using with protease inhibitors (either boosted or un-boosted with ritonavir). In this situation therapeutic drug monitoring may play a role in optimising response. There needs to be care when using many drugs with NNRTIs e.g. methadone, oral contraceptives, rifampicin, and there are some definite contraindications. By understanding pharmacological principles, it is possible to optimise use of multi-drug regimens.

Cardiovascular disease reduction in the outpatient kidney transplant clinic

Cardiovascular disease (CVD) is an important cause of death in kidney transplant recipients. Future CVD mortality was estimated by a risk calculator in all patients (n = 439) with a functioning transplant (>6 months), followed at our center. In addition to CURRENT mortality rates, an OPTIMAL rate (adding anti-hypertensive and lipid-lowering therapy in uncontrolled patients) and an HISTORIC rate (higher systolic blood pressures and the absence of statin use in our population 5 years ago) were also calculated. Overall, the predicted CURRENT CVD mortality rates are 0.82 (95% CI 0.81-0.83) of HISTORIC rates. Predicted OPTIMAL CVD mortality rates are 0.90 (95% CI 0.87-0.92) of CURRENT rates. To achieve OPTIMAL rates, a 27% increase in blood pressure and lipid-lowering drug use is required. There were few contraindications to these medications, implying that physician prescribing was the major barrier to minimizing risk. Despite OPTIMAL rates, the transplant population's relative risk is 2.3 (median, 95% CI 2.1-2.5) times higher than that in the general population. Therefore, targeted therapy to reduce CVD risk can have substantial benefit, but CVD mortality may continue to exceed that in the general population.

Ezetimibe: A Selective Cholesterol Absorption Inhibitor

Ezetimibe is the first agent of a novel class of selective cholesterol absorption inhibitors recently approved by the Food and Drug Administration for treatment in the United States. Ezetimibe inhibits the absorption of biliary and dietary cholesterol from the small intestine without affecting the absorption of fat-soluble vitamins, triglycerides, or bile acids. Ezetimibe localizes at the brush border of the small intestine and decreases cholesterol uptake into the enterocytes. Preclinical studies demonstrated lipid-lowering properties of ezetimibe as monotherapy and showed a synergistic effect in combination with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). The efficacy and safety of ezetimibe 10 mg/day have been established in phase III clinical trials. In these trials, ezetimibe was investigated as monotherapy, as an add-on to ongoing statin therapy, and as combination therapy with statins in patients with primary hypercholesterolemia. In addition, ezetimibe has been evaluated in patients with homozygous and heterozygous familial hypercholesterolemia and in those with sitosterolemia. When given as monotherapy or in combination with statins or fenofibrate, ezetimibe reduces low-density lipoprotein cholesterol (LDL) by 15-20% while increasing high-density lipoprotein cholesterol by 2.5-5%. Unlike other intestinally acting lipid-lowering agents, ezetimibe does not adversely affect triglyceride levels and, due to its minimal systemic absorption, drug interactions are few. Ezetimibe's side-effect profile resembles that of placebo when given as monotherapy or in combination with statins. In clinical practice, ezetimibe has a role as monotherapy for patients who require modest LDL reductions or cannot tolerate other lipid-lowering agents. In combination therapy with a statin, ezetimibe is used in patients who cannot tolerate high statin doses or in those who need additional LDL reductions despite maximum statin doses.

Haplotypes of the cholesteryl ester transfer protein gene predict lipid-modifying response to statin therapy

Cholesteryl ester transfer protein (CETP) plays a central role in high-density lipoprotein (HDL) metabolism. Single nucleotide polymorphisms (SNPs) and haplotypes in the CETP gene were determined in 98 patients with untreated dyslipidemias and analyzed for associations with plasma CETP and plasma lipids before and during statin treatment. Individual CETP SNPs and haplotypes were both significantly associated with CETP enzyme mass and activity. However, only certain CETP haplotypes, but not individual SNPs, significantly predicted the magnitude of change in HDL cholesterol (HDL-C) and triglycerides. After adjusting for covariates and multiple testing, the TTCAAA haplotype showed a gene-dose effect in predicting the HDL-C increase (P=0.03), while the TTCAAAGGG and AAAGGG haplotypes predicted a decrease in triglycerides (P=0.04 both). This is the first study to demonstrate that SNP haplotypes derived from allelic SNP combinations in the CETP gene were more informative than single SNPs in predicting the response to lipid-modifying therapy with statins.

Bridging the Treatment Gap: Improving Compliance With Lipid-Modifying Agents and Therapeutic Lifestyle Changes

Despite the large burden of cardiovascular disease on society, abnormal lipid levels, which are associated with an increase in coronary heart disease mortality, are not being adequately managed in many individuals. Poor patient compliance with therapeutic lifestyle changes and lipid-modifying therapies contribute to this treatment gap. If management of lipid levels is to reduce cardiovascular mortality effectively, poor compliance with treatment needs to be understood and addressed. Educating and motivating patients to understand the need for compliance with continued therapy is an important step for ensuring that the benefits of lipid management cited in clinical trials are translated to the general population. This will require a proactive approach from both patients and physicians. Well-tolerated and effective therapies may also help compliance by reducing the incidence of side effects and the need for complex dosing regimens. Suboptimal treatment of lipid levels is currently limiting the effectiveness of primary and secondary prevention of coronary heart disease; methods for improving compliance should be a key strategy to overcoming this problem.

CHD prevention: the importance of identifying dyslipidaemia

Coronary heart disease (CHD) is the major cause of death worldwide (Murray and Lopez, 1997) and confers a significant socio-economic burden on all populations. The careful identification and optimal treatment of all individuals at risk of CHD is necessary for significant reductions in morbidity and mortality to be realized. This strategy demands an integrated approach by healthcare teams, with nurses playing a significant role at all stages of patient care. Guidelines advocate lipid lowering as a central component of all treatment regimens. Identification by nurses of all individuals who would benefit from lifestyle and therapeutic interventions to normalize lipid profiles, as well as the recognition of the impact of increasing prevalances of diabetes and obesity on the risk of developing CHD, are clearly critical. Nurses also have an important role to play in the implementation of drug regiments and lifestyle changes, including appropriate ways to minimize the treatment gap and maximize patient concordance.

Peroxisome proliferator-activated receptor (PPAR)-alpha activation prevents diabetes in OLETF rats: comparison with PPAR-gamma activation

Lipid accumulation in nonadipose tissues is closely related to the development of type 2 diabetes in obese subjects. We examined the potential preventive effect of peroxisome proliferator-activated receptor (PPAR)-alpha and PPAR-gamma stimulation on the development of diabetes in obese diabetes-prone OLETF rats. Chronic administration of a PPAR-alpha agonist (0.5% [wt/wt] fenofibrate) or a PPAR-gamma agonist (3 mg x kg(-1) x day(-1) rosiglitazone) completely prevented the development of glycosuria. Pancreatic islets from untreated OLETF rats underwent sequential hypertrophy and atrophy, which was completely prevented by chronic fenofibrate treatment. In contrast, rosiglitazone treatment did not affect islet hypertrophy at earlier stages but prevented beta-cell atrophy at later stages. Fenofibrate treatment decreased body weight and visceral fat, whereas rosiglitazone treatment increased body weight. Despite the opposite effects on adiposity, both drugs were equally effective in improving insulin actions in skeletal muscle. Furthermore, both drugs significantly decreased the triglyceride content in the soleus muscle and pancreatic islets. The present study demonstrates that the PPAR-alpha agonist fenofibrate prevents the development of diabetes in OLETF rats by reducing adiposity, improving peripheral insulin action, and exerting beneficial effects on pancreatic beta-cells.

Managing the spectrum of dyslipidemia in primary care

Dyslipidemia, especially elevated low-density lipoprotein cholesterol (LDL-C), increases the risk of coronary heart disease and subsequent morbidity or mortality. For more than a decade, the National Cholesterol Education Program (NCEP) has endeavored to raise awareness of the dangers of dyslipidemia and to encourage the implementation of recommended treatment strategies. However, despite this initiative, previously published NCEP targets were not met. The recently released NCEP-Adult Treatment Panel III guidelines recommend more aggressive LDL-C reduction, elevation of categorical low high-density lipoprotein binding protein, and increased monitoring of moderate triglyceride elevations. Although the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are the most powerful medications available to reduce LDL-C, studies have shown that more than half of patients treated with these drugs do not achieve therapeutic targets and the resultant decrease in coronary heart disease events. There are a number of possible reasons for this, including potency of the statins and a lack of compliance on the part of patients and providers. Another concern with the available statins is the issue of drug-drug interactions. Some of these concerns may be addressed by newer agents in this drug class that are in development. They appear to have the potential to induce even greater reductions in LDL-C and to positively affect other lipoproteins. They also have the potential for less risk of drug-drug interactions. Nurse practitioners can play a pivotal role in improving the management of dyslipidemia by ensuring the proper implementation of current guidelines, helping patients adhere to treatment protocols, and remaining abreast of developments that may pave the way toward even more effective intervention in the future.

Pyrazole derivatives as partial agonists for the nicotinic acid receptor

Nicotinic acid as a hypolipidemic agent appears unique due to its potential to increase HDL cholesterol levels to a greater extent than other drugs. However, it has some side effects, among which severe skin flushing is the most frequent and often limits patients' compliance. In a search for novel agonists for the recently identified and cloned G protein-coupled nicotinic acid receptor, we synthesized a series of substituted pyrazole-3-carboxylic acids that proved to have substantial affinity for this receptor. The affinities were measured by inhibition of [(3)H]nicotinic acid binding to rat spleen membranes. Potencies and intrinsic activities relative to nicotinic acid were determined by their effects on [(35)S]GTPgammaS binding to rat adipocyte and spleen membranes. Interestingly, most compounds were partial agonists. In particular, 2-diazabicyclo[3,3,0(4,8)]octa-3,8-diene-3-carboxylic acid (4c) and 5-propylpyrazole-3-carboxylic acid (4f) proved active with K(i) values of approximately 0.15 microM and EC(50) values of approximately 6 microM, while their intrinsic activity was only approximately 50% when compared to nicotinic acid. Even slightly more active was 5-butylpyrazole-3-carboxylic acid (4g) with a K(i) value of 0.072 microM, an EC(50) value of 4.12 microM, and a relative intrinsic activity of 75%. Of the aralkyl derivatives, 4q (5-(3-chlorobenzyl)pyrazole-3-carboxylic acid) was the most active with a relatively low intrinsic activity of 39%. Partial agonism of the pyrazole derivatives was confirmed by inhibition of G protein activation in response to nicotinic acid by these compounds. The pyrazoles both inhibited the maximum effect elicited by 100 microM nicotinic acid and concentration dependently shifted nicotinic acid concentration-response curves to the right, pointing to a competitive mechanism of action.

Syntheses of 3-ethylidenequinuclidine derivatives as squalene synthase inhibitors. Part 2: enzyme inhibition and effects on plasma lipid levels

Squalene synthase (E.C. 2.5.1.21) is a microsomal enzyme which catalyzes the reductive dimerization of two molecules of farnesyl diphosphate to form squalene, and is involved in the first committed step in cholesterol biosynthesis. It is an attractive target for hypocholesterolemic and hypotriglyceridemic strategies. We synthesized a series of 3-ethylidenequinuclidine derivatives, and evaluated their ability to inhibit squalene synthase in vitro and to lower non-HDL cholesterol levels in hamsters. 3-Ethylidenequinuclidine derivatives incorporating an unsubstituted 9H-carbazole moiety reduced plasma non-HDL cholesterol levels and did not affect plasma transaminase levels, indicating a lack of hepatotoxicity. Among the novel compounds, (Z)-2-[2-(quinuclidin-3-ylidene)ethoxy]-9H-carbazole hydrochloride 8 (YM-53579) and (E)-2-[2-fluoro-2-(quinuclidin-3-ylidene)ethoxy]-9H-carbazole hydrochloride 28 (YM-53601) were potent inhibitors of squalene synthase derived from human hepatoma cells, with IC(50) values of 160 and 79 nM, respectively. They also reduced plasma non-HDL cholesterol levels in hamsters by approximately 50 and 70%, respectively, at an oral dose of 50 mg/kg/day for 5 days.