Metabolic modes of action of the statins in the hyperlipoproteinemias

Hypertriglyceridemic hyperapoB and the development and resolution of nonalcoholic fatty liver disease: a cohort study

Hypertriglyceridemic hyperapoB is an adverse lipoprotein phenotype characterized by low high density lipoprotein (HDL) cholesterol, high triglycerides, high apolipoprotein B (ApoB), and low low density lipoprotein (LDL) cholesterol to ApoB ratio. We investigated whether and to what extent hypertriglyceridemic hyperapoB associates with the incidence and resolution of nonalcoholic fatty liver disease (NAFLD). This prospective cohort study included 9,019 Chinese participants 40 years or older, from 2010 to 2015. Logistic regression models were used to examine the odds ratios (ORs) for the incidence and resolution of NAFLD associated with the hypertriglyceridemic hyperapoB lipoprotein phenotype and individual lipid and lipoprotein parameters. During a median 4.3 years of follow-up, compared with participants with optimal phenotype, the fully adjusted ORs (95% CIs) for participants with hypertriglyceridemic hyperapoB were 2.75 (1.91, 3.95) and 0.57 (0.33, 1.00) for incidence and resolution of NAFLD, respectively. These associations were consistent across subgroup participants with varied demographic, lifestyle, and metabolic status. Individually, each unit increase in HDL cholesterol (OR: 0.98; 95% CI: 0.97, 0.99), natural logarithm-transformed triglycerides (1.89; 1.52, 2.36), and ApoB (1.006; 1.002, 1.011) was independently associated with NAFLD incidence, and only triglycerides (0.77; 0.60, 0.99) was independently associated with NAFLD resolution. Our findings suggest that Chinese adults with hypertriglyceridemic hyperapoB have a higher risk of NAFLD incidence and a lower likelihood of NAFLD resolution. These associations were stable among adults with different demographic, lifestyle, and metabolic status, supporting hypertriglyceridemic hyperapoB as a valuable clinical marker for the prevention and control of NAFLD.

Simvastatin Downregulates Cofilin and Stathmin to Inhibit Skeletal Muscle Cells Migration

Statins are the most effective therapeutic agents for reducing cholesterol synthesis. Given their widespread use, many adverse effects from statins have been reported; of these, musculoskeletal complications occurred in 15% of patients after receiving statins for 6 months, and simvastatin was the most commonly administered statin among these cases. This study investigated the negative effects of simvastatin on skeletal muscle cells. We performed RNA sequencing analysis to determine gene expression in simvastatin-treated cells. Cell proliferation and migration were examined through cell cycle analysis and the transwell filter migration assay, respectively. Cytoskeleton rearrangement was examined through F-actin and tubulin staining. Western blot analysis was performed to determine the expression of cell cycle-regulated and cytoskeleton-related proteins. Transfection of small interfering RNAs (siRNAs) was performed to validate the role of cofilin and stathmin in the simvastatin-mediated inhibition of cell migration. The results revealed that simvastatin inhibited the proliferation and migration of skeletal muscle cells and affected the rearrangement of F-actin and tubulin. Simvastatin reduced the expression of cofilin and stathmin. The knockdown of both cofilin and stathmin by specific siRNA synergistically impaired cell migration. In conclusion, our results indicated that simvastatin inhibited skeletal muscle cell migration by reducing the expressions of cofilin and stathmin.

Postoperative Cardiac Surgery Outcomes in a Statin-Native Population

Background

Statin utilization had been associated with improved survival after cardiac surgery. We aim to study whether perioperative treatment with statin could be associated with increased postoperative complications.

Design

This was a retrospective, descriptive, single-center study.

Settings

We analyzed morbidity after cardiac surgery as well as the outcome related to statin therapy in a tertiary cardiac center.

Patients

A total of 202 consecutive patients were enrolled over 1 year after cardiac surgery.

Intervention

Patients were divided into two groups; Group I - statin users and Group II - nonusers.

Measurements

Measurements were baseline and follow-up laboratory markers for muscular injury including cardiac muscle and hepatic injuries and renal injuries.

Results

The incidence of rhabdomyolysis and elevation of liver enzymes did not differ between both groups. Postoperative atrial fibrillation was significantly lower in the statin group (P = 0.02). In addition, peak cardiac troponin and creatine kinase-MB did not differ significantly in the statin group. Statin-treated group had significant lower length of mechanical ventilation, and length of stay in the Intensive Care Unit and hospital (P = 0.036, 0.04, and 0.027, respectively).

Conclusions

Therapy with statin before cardiac surgeries was not associated with high incidence of adverse events.

Cu-Catalyzed ligand-free synthesis of rosuvastatin based novel indole derivatives as potential anticancer agents

Rosuvastatin based indoles showed anti-proliferative and apoptotic activities and an increase of p21 mRNA expression levels in zebrafish larvae.

[Pathogenetic justification of statin use in ischaemic stroke prevention according to inflammatory theory in development of atherosclerosis]

There is an inflammatory component in the pathogenesis of ischaemic stroke, which plays an important role in inducing atherothrombotic and embolic stroke. Statins, HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase inhibitors are widely used in the primary and secondary prevention of ischaemic stroke. It has been proved that beyond their main effect on inhibition of endogenous cholesterol, they also modify the inflammatory process. Additional benefits from the use of statins result from their effect on the immune system. Increased risk of recurrent vascular episodes and risk of death after statin withdrawal in patients with vascular disorders is connected with termination of the anti-inflammatory effect of these drugs. The authors highlight that because of the anti-inflammatory effect of statins it is reasonable to use them in all patients at risk of ischaemic stroke, including those with atrial fibrillation.

Comparative reactivity of remnant-like lipoprotein particles (RLP) and low-density lipoprotein (LDL) to LDL receptor and VLDL receptor: effect of a high-dose statin on VLDL receptor expression

BACKGROUND

Comparison of the reactivity of remnant-like lipoprotein particles (RLP) and LDL particles to LDL receptor and VLDL receptor has not been investigated.

METHODS

LDL receptor- or VLDL receptor-transfected ldlA-7, HepG2 and L6 cells were used. Human LDL and rabbit β-VLDL were isolated by ultracentrifugation. Human RLP was isolated using an immunoaffinity mixed gel. The effect of statin on lipoprotein receptors was examined.

RESULTS

Both LDL receptor and VLDL receptor recognized RLP. In LDL receptor transfectants, RLP, β-VLDL and LDL all bound to LDL receptor. Cold RLP competed efficiently with DiI-β-VLDL; however, cold LDL competed weakly. In VLDL receptor transfectants, RLP and β-VLDL bound to VLDL receptor, but not LDL. RLP bound to VLDL receptor with higher affinity than β-VLDL because of higher apolipoprotein E in RLP. LDL receptor expression was induced in HepG2 by the low concentration of statin while VLDL receptor expression was induced in L6 myoblasts at higher concentration.

CONCLUSIONS

RLP are bound to hepatic LDL receptor more efficiently than LDL, which may explain the mechanism by which statins prevent cardiovascular risk by primarily reducing plasma RLP rather than by reducing LDL. Additionally, a high-dose of statins also may reduce plasma RLP through muscular VLDL receptor.

Perioperative statin use: an update

HMG CoA reductase inhibitors (statins) are a proven modality to reduce serum cholesterol and have been shown to reduce morbidity and mortality in cardiovascular patients. Statins have also demonstrated improvements in postoperative outcomes among patients taking them in the perioperative period. Many of the studies are limited to select patient populations and/or select surgeries. This review will give an overview of the pharmacology of statins, summarize the mechanisms of the beneficial effects of statins, and provide an overview of evidence in the use of statins in the perioperative period.

Ecotoxicological aspects related to the presence of pharmaceuticals in the aquatic environment

Pharmaceuticals are biologically active and persistent substances which have been recognized as a continuing threat to environmental stability. Chronic ecotoxicity data as well as information on the current distribution levels in different environmental compartments continue to be sparse and are focused on those therapeutic classes that are more frequently prescribed and consumed. Nevertheless, they indicate the negative impact that these chemical contaminants may have on living organisms, ecosystems and ultimately, public health. This article reviews the different contamination sources as well as fate and both acute and chronic effects on non-target organisms. An extensive review of existing data in the form of tables, encompassing many therapeutic classes is presented.

Simvastatin induces apoptosis of fibroblast-like synoviocytes

Background:

Statins (3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors) exert favorable effects on lipoprotein metabolism, but appeared to possess anti-inflammatory properties among others, as suggested by their ability to inhibit collagen-induced arthritis in mice. Their activity in fibroblast-like synovial cells (FLS) has not yet been studied.

Objectives:

To evaluate the effect of varying doses of simvastatin on apoptosis of FLS.

Methods:

Synovial tissue, obtained during total knee replacement due to osteoarthritis, was cut into small pieces and cultured in Petri dishes with test materials, as previously described. FLS were incubated for 48 hours with 1 μmol/ml, 5 μmol/ ml, 15 μmol/ml and 50 μmol/ml of simvastatin. Following incubation, apoptosis was analyzed by two-dimensional flow cytometry (FACS) using annexin V/PI staining according to the manufacturer’s instructions.

Results:

Different concentrations of simvastatin induced apoptosis of FLS. The level proportion of apoptotic cells of resting or activated with lipopolysaccharide (LPS; 3 μg/ml) FLS, not treated with simvastatin, was 21%. At 48 hours, the rate of apoptosis of activated fibroblasts, incubated with 1 μmol/ml, 5 μmol/ml, 15 and 50 μmol/ml was 22%, 32%, 48% and 41% respectively. Synovial cell viability evaluated by tetrazolium salt XXT was unaffected by the simvastatin concentration used.

Conclusion:

Varying concentrations of simvastatin induce apoptosis of activated fibroblast-like synoviocytes, suggesting another possible mechanism of anti-inflammatory effects of statins in inflammatory conditions.

Dose-dependent effect of rosuvastatin on apolipoprotein B-100 kinetics in the metabolic syndrome

In a randomized, double-blind, crossover trial of 5-week treatment period with placebo or rosuvastatin (10 or 40 mg/day) with 2-week placebo wash-outs between treatments, the dose-dependent effect of rosuvastatin on apolipoprotein (apo) B-100 kinetics in metabolic syndrome subjects were studied. Compared with placebo, there was a significant dose-dependent decrease with rosuvastatin in plasma cholesterol, triglycerides, LDL cholesterol, apoB and apoC-III concentrations and in the apoB/apoA-I ratio, lathosterol:cholesterol ratio, HDL cholesterol concentration and campesterol:cholesterol ratio also increased significantly. Rosuvastatin significantly increased the fractional catabolic rates (FCR) of very-low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and LDL-apoB and decreased the corresponding pool sizes, with evidence of a dose-related effect. LDL apoB production rate (PR) fell significantly with rosuvastatin 40 mg/day with no change in VLDL and IDL-apoB PR. Changes in triglycerides were significantly correlated with changes in VLDL apoB FCR and apoC-III concentration, and changes in lathosterol:cholesterol ratio were correlated with changes in LDL apoB FCR, the associations being more significant with the higher dose of rosuvastatin. In the metabolic syndrome, rosuvastatin decreases the plasma concentration of apoB-containing lipoproteins by a dose-dependent mechanism that increases their rates of catabolism. Higher dose rosuvastatin may also decrease LDL apoB production. The findings provide a dose-related mechanism for the benefits of rosuvastatin on cardiovascular disease in the metabolic syndrome.

A 12-Week, Prospective, Open-Label Analysis of the Effect of Rosuvastatin on Triglyceride-Rich Lipoprotein Metabolism in Patients with Primary Dyslipidemia

BACKGROUND

Although the effect of statins on lowering low-density lipoprotein cholesterol (LDL-C) has been extensively studied, their hypotriglyceridemic capacity is not fully understood.

OBJECTIVE

The present study examined clinical and laboratory factors potentially associated with the triglyceride (TG)-lowering effect of rosuvastatin.

METHODS

Eligible patients had primary dyslipidemia and a moderate risk of heart disease. Patients were prescribed rosuvastatin 10 mg/d in an open-label fashion and kept 3-day food diaries. Laboratory measurements, performed at baseline and 12 weeks, included serum lipid parameters (total cholesterol [TC], TGs, LDL-C, high-density lipoprotein cholesterol [HDL-C], and apolipoprotein [apo] levels), non-lipid metabolic variables (including carbohydrate metabolism parameters and renal, liver, and thyroid function tests), and LDL-subfraction profile (by high-resolution 3% polyacrylamide gel electrophoresis). Tolerability was assessed at each visit.

RESULTS

Participants were 75 hyperlipidemic patients (39 men and 36 women; mean age, 51.7 years). At 12 weeks, TC levels were reduced by 35.1% (P < 0.001), TGs by 15.2% (P < 0.001), LDL-C by 48.5% (P < 0.001), apoE by 35.4% (P < 0.001), and apoE by 17.3% (P < 0.001) from baseline, whereas HDL-C and apoA1 levels were not significantly changed. Stepwise linear regression analysis showed that baseline TG levels were most significantly correlated (R(2) = 42.0%; P < 0.001) with the TG-lowering effect of rosuvastatin, followed by the reduction in apoCIII levels (R(2) = 13.6%; P < 0.01). Rosuvastatin use was associated with a reduction in cholesterol mass of both large LDL particles (mean [SD], from 150.5 [36.6] to 90.5 [24.3] mg/dL; P < 0.001) and small, dense LDL (sdLDL) particles (from 11.5 [8.4] to 6.6 [4.5] mg/dL; P < 0.001). Rosuvastatin had no effect on cholesterol distribution of the LDL subfractions (mean [SD], large particles, from 90.8% [7.0%] to 91.8% [5.1%]; sdLDL, from 7.1% [4.7%] to 7.5% [4.8%]) or the mean LDL particle size (from 26.5 [4.2] to 26.6 [4.0] rim). A significant increase in mean LDL particle size after rosuvastatin treatment (mean [SD], from 26.4 [0.4] to 26.9 [0.4] rim; P = 0.02) was observed only in patients with baseline TG levels > or =120 mg/dL. No serious adverse events requiring study treatment discontinuation were reported. One patient who presented with headache and 2 patients who presented with fatigue quickly recovered without discontinuing rosuvastatin treatment. A posttreatment elevation in aminotransferase levels <3-fold the upper limit of normal (ULN) was recorded in 5 (6.7%) patients, and 2 (2.7%) patients experienced elevated creatine kinase concentrations <5-fold ULN.

CONCLUSION

Baseline TG levels were the most important independent variable associated with the TG-lowering effect of rosuvastatin.

[Atherosclerosis plaque regression]

INTRODUCTION

The natural history of atherosclerosis can be assessed using different methods including quantitative coronary angiography, intravascular ultrasound, B-mode ultrasound, electron-beam computed tomography and magnetic resonance imaging.

REGRESSION OF ATHEROSCLEROSIS

Although the first investigations regarding effects of low cholesterol diet on atherosclerosis progression in animals were performed almost 100 years ago, researches on potential induction of atherosclerosis regression in humans began only recently, in the past 20 years. To date, many studies assessing different drugs and study protocols on natural evolution of atherosclerosis have been performed. They include use of diet and physical activity, different hypolipemic drugs, especially statins, ACE inhibitors, calcium channel blockers, hormone replacement therapy, antioxidants, and recently, use of recombinant apolipoproteins.

STATINS AND ATHEROSCLEROSIS

It has been established that statins given to patients with, or even without verified coronary artery disease, slow progression of atherosclerosis. These effects of statins are likely due to a combination of their metabolic and pleiotropic properties and might in part explain the positive effects of these drugs on overall cardiovascular mortality and morbidity. Furthermore, applied in high doses, these drugs may induce real atherosclerosis regression, especially in asymptomatic patients in the early stages of the disease.

The effect of high-dose simvastatin on triglyceride-rich lipoprotein metabolism in patients with type 2 diabetes mellitus

Statins decrease triglycerides (TGs) in addition to decreasing low density lipoprotein-cholesterol. Although the mechanism for the latter effect is well understood, it is still unclear how TG decrease is achieved with statin therapy. Because hypertriglyceridemia is common in obese patients with type 2 diabetes mellitus, we studied triglyceride-rich lipoprotein triglyceride (TRL-TG) turnover in 12 such subjects using stable isotopically labeled glycerol. The diabetic subjects were studied after 12 weeks of placebo and after a similar course of therapy with simvastatin (80 mg daily) in a single-blind design. The results were compared with those from six nonobese nondiabetic control subjects. Simvastatin therapy reduced serum TGs by 35% in the diabetic subjects. Compared with the control subjects, TRL-TG secretion was almost 2-fold higher in the diabetic subjects (45.4 +/- 4.9 vs. 24.4 +/- 1.9 micromol/min; P < 0.002) and was unaffected by simvastatin therapy. However, TRL-TG clearance was significantly increased in the diabetic subjects during simvastatin treatment compared with placebo (0.25 +/- 0.03 vs. 0.16 +/- 0.02 pools/h; P < 0.002). This change was accompanied by a 49% increase in preheparin plasma lipase activity (P < 0.03) and a 21% increase in postheparin LPL activity (P < 0.01). Together, these findings provide strong evidence that the effect of statins on serum TGs is related to an increase in LPL activity, resulting in accelerated delipidation of TRL particles. The effect of high-dose simvastatin on triglyceride-rich lipoprotein metabolism in patients with type 2 diabetes mellitus.

Plasma kinetics of free and esterified cholesterol in familial hypercholesterolemia: Effects of simvastatin

The objective of this study was to evaluate the kinetics of both free and esterified forms of cholesterol contained in a emulsion that binds to LDL receptors (LDE) in subjects with heterozygous familial hypercholesterolemia (FH), and the same subjects under the effects of high-dose simvastatin treatment, as compared with a control normolipidemic group (NL). Twenty-one FH patients (44.0 +/- 13.0 yr, 12 females, LDL cholesterol levels 6.93 +/- 1.60 mmol/L) and 22 normolipidemic patients (44.0 +/- 15.0, 10 females, LDL cholesterol levels 3.15 +/- 0.62 mmol/L) were injected intravenously with 14C-cholesteryl ester and 3H-cholesterol. FH patients were also evaluated after 2 mon of 40 or 80 mg/d simvastatin treatment, and plasma samples were collected over 24 h to determine the residence time (RT, in h) of both LDE labels, expressed as the median (25%; 75%). The RT of both 14C-cholesteryl ester and 3H-cholesterol were greater in FH than in NL [FH: 36.0 (20.5; 1191.0), NL: 17.0 (12.0-62.5), P = 0.015; and FH: 52.0 (30.0; 1515.0); NL 20.5 (14.0-30.0) P < 0.0001]. Treatment reduced LDL cholesterol by 36% (P < 0.0001), RT of 14C-cholesteryl ester by 49% (P = 0.0029 vs. baseline), and 3H-cholesterol RT by 44% (P = 0.019 vs. baseline). After treatment, the RT values of 14C-cholesteryl ester in the FH group approached the NL values (P = 0.58), but the RT of 3H-cholesterol was still greater than those for the NL group (P = 0.01). The removal of LDE cholesteryl esters and free cholesterol was delayed in FH patients. Treatment with a high dose of simvastatin normalized the removal of cholesterol esters but not the removal of free cholesterol.

Rosuvastatin Reduces Plasma Lipids by Inhibiting VLDL Production and Enhancing Hepatobiliary Lipid Excretion in ApoE*3-Leiden Mice

The present study was designed to investigate the lipid-lowering properties and mechanisms of action of a new HMG-CoA reductase inhibitor, rosuvastatin, in female ApoE*3-Leiden transgenic mice. Mice received a high fat/cholesterol (HFC) diet containing either rosuvastatin (0 [control], 0.00125%, 0.0025%, or 0.005% [w/w]) or 0.05% (w/w) lovastatin. The highest dose of rosuvastatin reduced plasma cholesterol and triglyceride levels by 39% and 42%, respectively, compared with the HFC control. Lovastatin had no effect on plasma cholesterol and triglyceride levels. In ApoE*3-Leiden mice on a chow diet, rosuvastatin (0.005% [w/w]) decreased plasma cholesterol levels by 35% without having an effect on triglyceride levels. On a chow diet, expression of genes involved in cholesterol biosynthesis and uptake in the liver was increased by rosuvastatin. Further mechanistic studies in HFC-fed mice showed that rosuvastatin treatment resulted in decreased hepatic VLDL-triglyceride and VLDL-apolipoprotein B production. VLDL lipid composition remained unchanged, indicating a reduction in the number of VLDL particles secreted. Lipolytic activity and expression of genes involved in cholesterol and triglyceride synthesis and beta-oxidation of fatty acids in the liver were not affected by rosuvastatin treatment, and hepatic lipid content did not change. However, activity of hepatic diacylglycerol acyltransferase was significantly decreased by 25% after rosuvastatin treatment. Moreover, biliary excretion of cholesterol, phospholipids, and bile acids was increased during treatment. The results indicate that rosuvastatin treatment in ApoE*3-Leiden mice on a HFC diet leads to redistribution of cholesterol and triglycerides in the body, both by reduced hepatic VLDL production and triglyceride synthesis and by enhanced hepatobiliary removal of cholesterol, bile acids, and phospholipids, resulting in substantial reductions in plasma cholesterol and triglyceride levels.

Dyslipidemia in visceral obesity: mechanisms, implications, and therapy

Visceral obesity is frequently associated with high plasma triglycerides and low plasma high density lipoprotein-cholesterol (HDL-C), and with high plasma concentrations of apolipoprotein B (apoB)-containing lipoproteins. Atherogenic dyslipidemia in these patients may be caused by a combination of overproduction of very low density lipoprotein (VLDL) apoB-100, decreased catabolism of apoB-containing particles, and increased catabolism of HDL-apoA-I particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance. Weight reduction, increased physical activity, and moderate alcohol intake are first-line therapies to improve lipid abnormalities in visceral obesity. These lifestyle changes can effectively reduce plasma triglycerides and low density lipoprotein-cholesterol (LDL-C), and raise HDL-C. Kinetic studies show that in visceral obesity, weight loss reduces VLDL-apoB secretion and reciprocally upregulates LDL-apoB catabolism, probably owing to reduced visceral fat mass, enhanced insulin sensitivity and decreased hepatic lipogenesis. Adjunctive pharmacologic treatments, such as HMG-CoA reductase inhibitors, fibric acid derivatives, niacin (nicotinic acid), or fish oils, may often be required to further correct the dyslipidemia. Therapeutic improvements in lipid and lipoprotein profiles in visceral obesity can be achieved by several mechanisms of action, including decreased secretion and increased catabolism of apoB, as well as increased secretion and decreased catabolism of apoA-I. Clinical trials have provided evidence supporting the use of HMG-CoA reductase inhibitors and fibric acid derivatives to treat dyslipidemia in patients with visceral obesity, insulin resistance and type 2 diabetes mellitus. Since drug monotherapy may not adequately optimize dyslipoproteinemia, dual pharmacotherapy may be required, such as HMG-CoA reductase inhibitor/fibric acid derivative, HMG-CoA reductase inhibitor/niacin and HMG-CoA reductase inhibitor/fish oils combinations. Newer therapies, such as cholesterol absorption inhibitors, cholesteryl ester transfer protein antagonists and insulin sensitizers, could also be employed alone or in combination with other agents to optimize treatment. The basis for a multiple approach to correcting dyslipoproteinemia in visceral obesity and the metabolic syndrome relies on understanding the mechanisms of action of the individual therapeutic components.

Intérêt des statines en néphrologie

STATINS IN THE CASE OF CHRONIC RENAL DISEASE: Data of several large clinical trials in the general population demonstrated that hydroxymethyl glutaryl coenzyme A reductase inhibitors (statins) are effective in cardiovascular disease prevention with a relatively safe profile. Patients with chronic kidney disease (CKD) are at high risk for developing premature cardiovascular disease, so the benefits of statin therapy might be expected to be substantial in this population. Adjusted dose of statins to calcinurine inhibitors and renal function seem to exhibit a favorable risk/benefit ratio in CKD patients.

STUDY RESULTS

Statin use is CKD patients has been associated with a certain efficacy of cardiovascular disease prevention in several uncontrolled trials, and one randomized trial in renal transplant recipients. Several other large-scale randomized trials in CKD patients [4D (atorvastatin), AURORA (rosuvastatin) and SHARP (simvastatin/ezetimib) are currently underway. The results of these trials will permit evidence-based medicinal arguments justifying life-long clinical use of statins for cardiovascular prevention in CKD patients with progressive renal dysfunction, but data are inconclusive.

OTHER POSSIBLE EFFECTS

Clinically relevant plethoric effects associated with statin therapy in CKD patients might be restricted to the decrease of inflammation and oxidative stress.

Ciprofibrate therapy in patients with hypertriglyceridemia and low high density lipoprotein (HDL)-cholesterol: greater reduction of non-HDL cholesterol in subjects with excess body weight (The CIPROAMLAT study)

Background

Hypertriglyceridemia in combination with low HDL cholesterol levels is a risk factor for cardiovascular disease. Our objective was to evaluate the efficacy of ciprofibrate for the treatment of this form of dyslipidemia and to identify factors associated with better treatment response.

Methods

Multicenter, international, open-label study. Four hundred and thirty seven patients were included. The plasma lipid levels at inclusion were fasting triglyceride concentrations between 1.6–3.9 mM/l and HDL cholesterol ≤ 1.05 mM/l for women and ≤ 0.9 mM/l for men. The LDL cholesterol was below 4.2 mM/l. All patients received ciprofibrate 100 mg/d. Efficacy and safety parameters were assessed at baseline and at the end of the treatment. The primary efficacy parameter of the study was percentage change in triglycerides from baseline.

Results

After 4 months, plasma triglyceride concentrations were decreased by 44% (p < 0.001). HDL cholesterol concentrations were increased by 10% (p < 0.001). Non-HDL cholesterol was decreased by 19%. A greater HDL cholesterol response was observed in lean patients (body mass index < 25 kg/m²) compared to the rest of the population (8.2 vs 19.7%, p < 0.001). In contrast, cases with excess body weight had a larger decrease in non-HDL cholesterol levels (-20.8 vs -10.8%, p < 0.001). There were no significant complications resulting from treatment with ciprofibrate.

Conclusions

Ciprofibrate is efficacious for the correction of hypertriglyceridemia / low HDL cholesterol. A greater decrease in non-HDL cholesterol was found among cases with excess body weight. The mechanism of action of ciprofibrate may be influenced by the pathophysiology of the disorder being treated.

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.

Effect of atorvastatin on apolipoprotein B48 metabolism and low-density lipoprotein receptor activity in normolipidemic patients with coronary artery disease

We aimed to examine postprandial dyslipidemia in normolipidemic patients with coronary artery disease (CAD) and the effects of treatment with an hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitor (atorvastatin). Subjects with angiographicaly established CAD were randomized to treatment for 12 weeks with 80 mg/d atorvastatin or placebo and the effects on markers of postprandial lipoproteins and low-density lipoprotein (LDL)-receptor binding determined. LDL-receptor binding was determined in mononuclear cells, as a surrogate for hepatic activity. Fasting levels of cholesterol (P <.001), LDL-cholesterol (P <.001), apolipoprotein (apo)B(48) (P =.019), remnant-like particle-cholesterol (RLP-C) (P =.032), and total postprandial apoB(48) area under the curve (AUC) (P =.013) significantly decreased with atorvastatin compared with placebo. Atorvastatin also significantly increased LDL-receptor binding activity (P <.001), and this was correlated with changes in fasting apoB(48) (r =.80, P =.01). We report that aberrations in chylomicron metabolism in normolipidemic CAD subjects are correctable with atorvastatin by a mechanism involving increased LDL-receptor activity. This effect may, in part, explain the cardiovascular benefit of statins used in clinical trials of CAD patients with normal lipid levels.

Effect of atorvastatin on apolipoprotein B100 containing lipoprotein metabolism in type-2 diabetes

Seven hypertriglyceridemic patients with type-2 diabetes were treated with atorvastatin (40 mg/day) for 2 months. Kinetics of apolipoprotein B100 (apoB100)-containing lipoproteins were determined before and after atorvastatin treatment and compared with data obtained in five normolipidemic volunteers. ApoB100 metabolism was studied using stable isotopes and multicompartmental modeling. Compared with normolipidemic obese subjects, type-2 diabetic patients had a higher apoB100 concentration in very low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), and low-density lipoproteins (LDL) (P < 0.005). Kinetic analysis showed an increase in the total apoB100 production rate (P < 0.005) related to VLDL apoB100 overproduction (P < 0.005). Patients were also characterized by a lower fractional catabolic rate (FCR) in VLDL (not significant) or IDL (P < 0.005) mainly related to a decrease in VLDL and IDL delipidation rate (P < 0.005). Catabolism of LDL was also lower in diabetic patients (P < 0.05). Atorvastatin treatment significantly decreased plasma triglycerides (P < 0.05), total and LDL cholesterol (P < 0.05), apoB100 in LDL, IDL, and VLDL (P < 0.05). Treatment significantly decreased total apoB100 production rate (P < 0.05), but only for VLDL (P < 0.05). Treatment normalized FCR in IDL and LDL (P < 0.05). We concluded that atorvastatin improved lipid abnormalities in type-2 diabetic patients not only by increasing the clearance of apoB100-containing lipoproteins but also by decreasing VLDL production.

Differential regulation of lipoprotein kinetics by atorvastatin and fenofibrate in subjects with the metabolic syndrome

The metabolic syndrome is characterized by insulin resistance and abnormal apolipoprotein AI (apoAI) and apolipoprotein B-100 (apoB) metabolism that may collectively accelerate atherosclerosis. The effects of atorvastatin (40 mg/day) and micronised fenofibrate (200 mg/day) on the kinetics of apoAI and apoB were investigated in a controlled cross-over trial of 11 dyslipidemic men with the metabolic syndrome. ApoAI and apoB kinetics were studied following intravenous d(3)-leucine administration using gas-chromatography mass spectrometry with data analyzed by compartmental modeling. Compared with placebo, atorvastatin significantly decreased (P < 0.001) plasma concentrations of cholesterol, triglyceride, LDL cholesterol, VLDL apoB, intermediate-density lipoprotein (IDL) apoB, and LDL apoB. Fenofibrate significantly decreased (P < 0.001) plasma triglyceride and VLDL apoB and elevated HDL(2) cholesterol (P < 0.001), HDL(3) cholesterol (P < 0.01), apoAI (P = 0.01), and apoAII (P < 0.001) concentrations, but it did not significantly alter LDL cholesterol. Atorvastatin significantly increased (P < 0.002) the fractional catabolic rate (FCR) of VLDL apoB, IDL apoB, and LDL apoB but did not affect the production of apoB in any lipoprotein fraction or in the turnover of apoAI. Fenofibrate significantly increased (P < 0.01) the FCR of VLDL, IDL, and LDL apoB but did not affect the production of VLDL apoB. Relative to placebo and atorvastatin, fenofibrate significantly increased the production (P < 0.001) and FCR (P = 0.016) of apoAI. Both agents significantly lowered plasma triglycerides and apoCIII concentrations, but only atorvastatin significantly lowered (P < 0.001) plasma cholesteryl ester transfer protein activity. Neither treatment altered insulin resistance. In conclusion, these differential effects of atorvastatin and fenofibrate on apoAI and apoB kinetics support the use of combination therapy for optimally regulating dyslipoproteinemia in the metabolic syndrome.

Atorvastatin increases hepatic fatty acid beta-oxidation in sucrose-fed rats: comparison with an MTP inhibitor

We investigated the effects of atorvastatin, a widely used 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and BMS-201038, a microsomal triglyceride transfer protein (MTP) inhibitor, in sucrose-fed hypertriglyceridemic rats to determine whether the activation of beta-oxidation by these compounds plays a role in their hypotriglyceridemic effect. The decrease in plasma triglyceride concentration and post-Triton very low-density lipoprotein (VLDL) triglyceride concentration, a measure of hepatic triglyceride secretion, by atorvastatin (30 mg/kg p.o.) for 2 weeks was to approximately the same degree as those by BMS-201038 (0.3 mg/kg). Atorvastatin (30 mg/kg) increased hepatic beta-oxidation activity by 54% (P < 0.01), while BMS-201038 (0.3 mg/kg) had no significant effect. Atorvastatin decreased hepatic triglyceride, fatty acid and cholesteryl ester concentrations by 21% to 39%, whereas BMS-201038 increased these variables by 28% to 307%. In the atorvastatin-treated groups, a significant relationship was seen not only between hepatic beta-oxidation activity and hepatic triglyceride concentration (R(2) = 0.535, P < 0.01), but also between hepatic and plasma triglyceride concentrations (R(2) = 0.586, P < 0.01). No effect of atorvastatin on hepatic fatty acid synthesis was observed. These results indicate that the activation of hepatic beta-oxidation by atorvastatin may contribute to the decrease in hepatic triglyceride concentration, leading to its hypotriglyceridemic effect.

Pharmacodynamic effects and pharmacokinetics of a new HMG-CoA reductase inhibitor, rosuvastatin, after morning or evening administration in healthy volunteers

AIMS

To compare the lipid-regulating effects and steady-state pharmacokinetics of rosuvastatin, a new synthetic hydroxy methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, following repeated morning and evening administration in volunteers with fasting serum low-density lipoprotein cholesterol (LDL-C) concentrations < 4.14 mmol l-1.

METHODS

In this open-label two-way crossover trial 24 healthy adult volunteers were randomized to receive rosuvastatin 10 mg orally each morning (07.00 h) or evening (18.00 h) for 14 days. After a 4 week washout period, volunteers received the alternative regimen for 14 days. Rosuvastatin was administered in the absence of food.

RESULTS

Reductions from baseline in serum concentrations of LDL-C (-41.3%[morning]vs-44.2%[evening]), total cholesterol (-30.9%vs-31.8%), triglycerides (-17.1%vs-22.7%), and apolipoprotein B (-32.4%vs-35.3%) were similar following morning and evening administration. AUC(0,24 h) for plasma mevalonic acid (MVA), an in vivo marker of HMG-CoA reductase activity, decreased by -29.9% (morning) vs-32.6% (evening). Urinary excretion of MVA declined by -33.6% (morning) vs-29.2% (evening). The steady-state pharmacokinetics of rosuvastatin were very similar following the morning and evening dosing regimens. The Cmax values were 4.58 vs 4.54 ng ml-1, and AUC(0,24 h) values were 40.1 vs 42.7 ng ml-1 h, following morning and evening administration, respectively. There were no serious adverse events during the trial, and rosuvastatin was well tolerated after morning and evening administration.

CONCLUSIONS

The pharmacodynamic effects and pharmacokinetics of rosuvastatin are not dependent on time of dosing. Morning or evening administration is equally effective in lowering LDL-C.

Regulatory effects of HMG CoA reductase inhibitor and fish oils on apolipoprotein B-100 kinetics in insulin-resistant obese male subjects with dyslipidemia

Hepatic accumulation of lipid substrates perturbs apolipoproteinB-100 (apoB) metabolism in insulin-resistant, obese subjects and may account for increased risk of cardiovascular disease. In a placebo-controlled trial, we examined the independent and combined effects of decreasing cholesterol synthesis with atorvastatin (40 mg/day) and triglyceride synthesis with fish oils (4 g/day) on apoB kinetics. The subjects were 48 viscerally obese, insulin-resistant men with dyslipidemia who were studied in a fasted state. We found that atorvastatin significantly decreased plasma apoB-containing lipoproteins (P < 0.001, main effect) through increases in the fractional catabolic rate (FCR) of VLDL-, IDL-, and LDL-apoB (P < 0.01). Fish oils significantly decreased plasma levels of triglycerides and VLDL-apoB (P < 0.001), decreased the VLDL-apoB secretion rate (P < 0.01), but increased the conversion of VLDL to LDL (P < 0.001). Compared with placebo, combined treatment with atorvastatin and fish oils decreased VLDL-apoB secretion (P < 0.03) and increased the FCR of apoB in each lipoprotein fraction (P < 0.03) and the percent conversion of VLDL to LDL (P < 0.05). None of the treatments altered insulin resistance. In conclusion, in visceral obesity, atorvastatin increased hepatic clearance of all apoB-containing lipoproteins, whereas fish oils decreased hepatic secretion of VLDL-apoB. The differential effects of atorvastatin and fish oils on apoB kinetics support their combined use in correcting defective apoB metabolism in obese, insulin-resistant subjects.

Genetic factors play an important role in the pathogenesis of hyperlipidemia post-transplantation

BACKGROUND

Our purpose was to identify factors associated with hyperlipidemia post-transplantation in a Hispanic population.

METHODS

From 1985 to 1999, a kidney graft survival longer than 3 months occurred in 293 cases at the Instituto Nacional de la Nutrición. Most of the patients living in Mexico City were included (n = 83). The evaluation included a questionnaire, blood samples, and assessment of body composition and dietary habits. As many as possible first-degree relatives were studied.

RESULTS

Women had higher values of cholesterol (236 +/- 51 versus 215 +/-41; P < 0.05), low-density lipoprotein cholesterol (147 +/- 42 versus 131 +/- 34; P = 0.05), high-density lipoprotein cholesterol (57.3 +/- 14 versus 47.9 +/- 14; P = 0.002) and high-density lipoprotein-2 cholesterol. Isolated hypercholesterolemia was the most common lipid abnormality (40.9%), followed by mixed hyperlipidemia. Lipoprotein (a) greater than 30 mg/dL was found in 13 cases. Familial combined hyperlipidemia (FCHL) in the patient's relatives was a marker for dyslipidemia (odds ratio, 7.04; 95% confidence interval, 1.2 to 59.7). These cases had a worse lipid profile. Cyclosporine-treated FCHL patients had higher lipid levels compared with the non-FCHL, cyclosporine-treated patients. The effects of cyclosporine on the lipid levels were lower, but significant, after the exclusion of the FCHL cases.

CONCLUSION

Post-transplant dyslipidemia is determined by genetic and environmental factors. FCHL in the patient's relatives was associated with post-transplant hyperlipidemia; an additive effect with cyclosporine was found. The evaluation of the lipid profile of relatives may be useful for the assessment of the risk of post-transplant dyslipidemia.

Effect of Simvastatin on markers of triglyceride-rich lipoproteins in familial hypercholesterolaemia

BACKGROUND

We have previously shown elevated fasting plasma concentrations of intestinal remnants, as reflected by apolipoprotein (apo) B-48 and remnant-like particle-cholesterol (RLP-C) in patients with heterozygous familial hypercholesterolaemia (FH). We now investigate the effect of an HMG-CoA reductase inhibitor (simvastatin) on chylomicron remnant metabolism using the measurement of fasting apoB-48 and RLP-C in FH patients after long- and short-term simvastatin therapy and after a wash-out period. We also piloted the response of a breath test, involving the measurement of the fractional catabolic rate (FCR) of an intravenously injected chylomicron remnant-like emulsion labeled with cholesteryl (13)C-oleate.

METHODS

Fifteen FH patients were studied after > 6 months 40 mg day(-1) simvastatin treatment (long-term), a wash-out period (4 weeks), and 4 weeks of simvastatin treatment (short-term). Apolipoprotein B-48 was determined by SDS-PAGE and Western blotting/enhanced chemiluminescence and RLP-C by an immunoseparation assay. The FCR of the chylomicron remnant-like emulsion was determined from the appearance of (13)CO(2) in the breath and by multicompartmental mathematical modelling.

RESULTS

Both long- and short-term treatment with simvastatin were associated with decreases in the plasma concentration of apoB-48 (P < 0.05) and RLP-C (P < 0.001), but there was no significant change in the FCR of the emulsion.

CONCLUSIONS

We suggest that long- and short-term treatments with simvastatin have comparable effects in decreasing the plasma concentration of triglyceride-rich remnants in heterozygous FH, as measured by fasting apoB-48 and RLP-C. The mechanisms for this may involve decreased production of hepatic and possibly intestinal lipoproteins, and/or up-regulation of hepatic receptor clearance pathways, but these changes are apparently not associated with a change in remnant clearance as measured kinetically by the (13)CO(2) breath test.

Apolipoprotein B metabolism: tracer kinetics, models, and metabolic studies

The study of apolipoprotein (apo) B metabolism is central to our understanding of lipoprotein metabolism. However, the assembly and secretion of apoB-containing lipoproteins is a complex process. Specialized techniques, developed and applied to in vitro and in vivo studies of apoB metabolism, have provided insights into the mechanisms involved in the regulation of this process. Moreover, these studies have important implications for understanding both the pathophysiology as well as the therapeutic options for the dyslipidemias. The purpose of this review is to examine the role of apoB in lipoprotein metabolism and to explore the applications of kinetic analysis and multicompartmental modeling to the study of apoB metabolism. New developments and significant advances over the last decade are discussed.

SCAP ligands are potent new lipid-lowering drugs

Upregulation of low-density lipoprotein receptor (LDLr) is a key mechanism to control elevated plasma LDL-cholesterol levels. Here we identify a new class of compounds that directly binds to the sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP). We show that a 14C-labeled, photo-activatable analog specifically labeled both SCAP and a truncated form of SCAP containing the sterol-sensing domain. When administered to hyperlipidemic hamsters, SCAP ligands reduced both LDL cholesterol and triglycerides levels by up to 80% with a three-fold increase in LDLr mRNA in the livers. Using human hepatoma cells, we show that these compounds act through the sterol-responsive element of the LDLr promoter and activate the SCAP/SREBP pathway, leading to increased LDLr expression and activity, even in presence of excess of sterols. These findings have led to the identification of a class of compounds that represent a promising new class of hypolipidemic drugs.

Lipid-lowering drugs in lupus: an unexplored therapeutic intervention

Lipid-lowering drugs have been shown to have profound actions beyond modulation of lipid profiles. Statins have been shown to reduce the levels of pro-inflammatory cytokines and markers of acute phase response including C-reactive protein and serum amyloid A. Fibrates have also shown to reduce interleukin-6 levels. Both groups of drugs seem to act through a peroxisomal proliferating activating receptor alpha mechanism to achieve these actions. In lupus, there is profound activation of cytokine production and the acute phase response and a markedly increased risk for the development of atherosclerosis. The role of lipid-lowering drugs in the management of both the acute and chronic sequelae of lupus needs to be explored.

High-density lipoprotein cholesterol and triglyceride response with simvastatin versus atorvastatin in familial hypercholesterolemia

The clinical and biochemical determinants of high-density lipoprotein (HDL) and triglyceride response to simvastatin and atorvastatin were assessed in 150 patients with severe hyperlipidemia treated in a randomized open-trial format design. Triglyceride reduction was only dependent on HDL:apolipoprotein A1, change in apolipoprotein B, and dose response, whereas an increase in HDL was dependent on initial LDL, change in LDL or dose response, and therapy with simvastatin.

Effect of pravastatin on plasma removal of a chylomicron-like emulsion in men with coronary artery disease

The speed of the plasma removal of chylomicrons, the lipoproteins that carry dietary lipids absorbed in the intestine, may influence atherogenesis. Thus, the effects of a 30-day pravastatin or placebo treatment on the plasma kinetics of chylomicron-like emulsions were evaluated in 25 patients with coronary artery disease who were not hypertriglyceridemic in a randomized, single-blinded study. Eleven patients (53 +/- 4 years, 10 men) received pravastatin 40 mg/day and 14 received placebo (52 +/- 3 years, 13 men). Emulsions labeled with triolein ((3)H-TO) and cholesteryl oleate ((14)C-CO) to assess lipolysis and clearance of chylomicron and remnants, respectively, were injected intravenously in a bolus after a 12-hour fast. Blood samples were collected during 60 minutes to determine radio isotope decaying curves and fractional catabolic rates. Subjects were studied at baseline and after the treatment period. Compared with placebo (data expressed as mean +/- SEM), pravastatin treatment increased the (14)C-CO fractional catabolic rates (70 +/- 45% vs 18 +/- 10%, p = 0.01), reduced total cholesterol (-21 +/- 3% vs -3 +/- 2% p = 0.0001), low-density lipoprotein (LDL) cholesterol (-25 +/- 5% vs 4 +/- 6%, p = 0.0001), and apolipoprotein B levels (-22 +/- 3% vs -7 +/- 3% p = 0.01). (3)H-TO fractional catabolic rates, plasma triglycerides, very-low-density lipoprotein (VLDL) cholesterol and high-density lipoprotein (HDL) cholesterol variations did not differ between the groups. The fractional catabolic rate of (14)C-CO was inversely correlated with plasma apolipoprotein B levels (r = -0.7, p = 0.04). This suggests that besides reducing LDL cholesterol, pravastatin also increases chylomicron remnant clearance, with possible antiatherogenic implications.

Effects of simvastatin and atorvastatin administration on insulin resistance and respiratory quotient in aged dyslipidemic non-insulin dependent diabetic patients

One hundred and ninety-five aged (mean age: 67+/-4.8 years), non-insulin dependent diabetic patients underwent a randomised single-blind study for investigating the effect of statin administration on insulin resistance and respiratory quotient. After 4 weeks run-in period, all patients were randomised in three groups: placebo (n=67), simvastatin (10 mg/day) (n=61) and atorvastatin (5 mg/day) (n=67). Each treatment period lasted 8 weeks. At the beginning, after the run-in and at the end of the study, insulin resistance was assessed by homeostasis model assessment (HOMA) index, while respiratory quotient (Rq) was evaluated by indirect calorimetry. Statins versus placebo significantly lowered plasma total, LDL-, HDL-cholesterol and triglyceride concentrations and improved insulin resistance and Rq and metabolic control. Atorvastatin had a greater effect than simvastatin on plasma triglyceride concentration (-26.3+/-3.1 vs. -19.7+/-2.8%, P<0.03), HOMA index (-13.1+/-0.6 vs. -9.1+/-0.9%, P<0.05), Rq (5.9+/-0.4 vs. 3.1+/-0.5%, P<0.05) and glycosylated haemoglobin (-11.2+/-0.3 vs. -7. 1+/-0.4%, P<0.05). In the whole group of subjects (n=195) and at the end of the study, changes in plasma triglyceride concentrations were significantly correlated with the change in the HOMA index (r=0.44, P<0.001) and age and BMI adjusted-Rq (r=-0.32, P<0.005). Multivariate analyses demonstrated that decline in plasma triglyceride concentration was a significant determinant for explaining the effect of statin on insulin resistance and Rq. In conclusion our study demonstrates that statin administration is useful for controlling dyslipidemia in NIDDM patients and for improving the metabolic control. With regard to this latter aim, atorvastatin seems to be more powerful than simvastatin.

The magnitude of decrease in hepatic very low density lipoprotein apolipoprotein B secretion is determined by the extent of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition in miniature pigs

It has been postulated that the rate of hepatic very low density lipoprotein (VLDL) apolipoprotein (apo) B secretion is dependent upon the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. To test this hypothesis in vivo, apoB kinetic studies were carried out in miniature pigs before and after 21 days treatment with high-dose (10 mg/kg/day), atorvastatin (A) or simvastatin (S) (n = 5). Pigs were fed a diet containing fat (34% of calories) and cholesterol (400 mg/day; 0.1%). Statin treatment decreased plasma total cholesterol [31 (A) vs. 20% (S)] and low density lipoprotein (LDL) cholesterol concentrations [42 (A) vs. 24% (S)]. Significant reductions in plasma total triglyceride (46%) and VLDL triglyceride (50%) concentrations were only observed with (A). Autologous [131I]VLDL, [125I]LDL, and [3H]leucine were injected simultaneously, and apoB kinetic parameters were determined by triple-isotope multicompartmental analysis using SAAM II. Statin treatment decreased the VLDL apoB pool size [49 (A) vs. 24% (S)] and the hepatic VLDL apoB secretion rate [50 (A) vs. 33% (S)], with no change in the fractional catabolic rate (FCR). LDL apoB pool size decreased [39 (A) vs. 26% (S)], due to reductions in both the total LDL apoB production rate [30 (A) vs. 21% (S)] and LDL direct synthesis [32 (A) vs. 23% (S)]. A significant increase in the LDL apoB FCR (15%) was only seen with (A). Neither plasma VLDL nor LDL lipoprotein compositions were significantly altered. Hepatic HMG-CoA reductase was inhibited to a greater extent with (A), when compared with (S), as evidenced by 1) a greater induction in hepatic mRNA abundances for HMG-CoA reductase (105%) and the LDL receptor (40%) (both P < 0.05); and 2) a greater decrease in hepatic free (9%) and esterified cholesterol (25%) (both P < 0.05). We conclude that both (A) and (S) decrease hepatic VLDL apoB secretion, in vivo, but that the magnitude is determined by the extent of HMG-CoA reductase inhibition.

Hypolipidemic effect of NK-104, a potent HMG-CoA reductase inhibitor, in guinea pigs

The hypolipidemic effect of NK-104 and its mechanisms of action (effects on hepatic sterol synthesis, low density lipoprotein (LDL)-receptor expression and very low density lipoprotein (VLDL) secretion) were studied in guinea pigs using simvastatin as a reference substance. There was a dose-dependent and significant reduction of both plasma total cholesterol (17.4, 24.5 and 45.3% at 0.3, 1 and 3 mg/kg, respectively) and triglycerides (21.1 and 32.2% at 1 and 3 mg/kg, respectively) after 14-day administration of NK-104. Simvastatin at 30 mg/kg lowered plasma total cholesterol (25.0%) but not triglyceride levels. NK-104 (3 mg/kg) and simvastatin (30 mg/kg) inhibited hepatic sterol synthesis by approximately 80%, 3 h after dosing, and enhanced LDL receptor binding-capacity of liver membranes 1.5-fold after 14-day dosing. The former group accelerated LDL clearance somewhat more markedly than the latter, and increased fractional catabolic rate 1.8-fold (vs. 1.4-fold). Furthermore, only the NK-104 (3 mg/kg) suppressed VLDL secretion into the liver perfusate (triglyceride. 19.9%; apoB, 24.2%) with extensive reduction of hepatic sterol synthesis caused by prolonged action. These results indicate that NK-104 and simvastatin at 10 times the dosage of the former, similarly enhances hepatic LDL receptor; however, only NK-104 with prolonged action suppresses VLDL secretion to show higher cholesterol-lowering potency and triglyceride-reducing effect.