In vitro inhibitory effects of the optical isomers and metabolites of fluvastatin on copper ion-induced LDL oxidation

Statins and cardiovascular diseases: from cholesterol lowering to pleiotropy

Statins are 3-hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which are prescribed extensively for cholesterol lowering in the primary and secondary prevention of cardiovascular disease. Recent compelling evidence suggests that the beneficial effects of statins may not only be due to their cholesterol lowering effects, but also, to their cholesterol-independent or pleiotropic effects. Through these so-called pleiotropic effects, statins are directly involved in restoring or improving endothelial function, attenuating vascular remodeling, inhibiting vascular inflammatory response, and perhaps, stabilizing atherosclerotic plaques. These cholesterol-independent effects of statins are predominantly due to their ability to inhibit isoprenoid synthesis, the products of which are important lipid attachments for intracellular signaling molecules, such as Rho, Rac and Cdc42. In particular, inhibition of Rho and its downstream target, Rho-associated coiled-coil containing protein kinase (ROCK), has emerged as the principle mechanisms underlying the pleiotropic effects of statins. This review provides an update of statin-mediated vascular effects beyond cholesterol lowering and highlights recent findings from bench to bedside to support the concept of statin pleiotropy.

Neutrophil Superoxide Anion Generation During Atorvastatin and Fluvastatin Therapy Used in Coronary Heart Disease Primary Prevention

Neutrophil superoxide anion generation was measured during atorvastatin and fluvastatin therapy in patients with coronary heart disease (CHD) risk. The patients were randomly allotted into three groups. The atorvastatin group comprised 17 patients who were administered the drug orally 10 mg a day at bed time. The fluvastatin group consisted of 18 patients on an oral dose of 40 mg once daily at bed time. The control group comprised 12 healthy subjects with no drug administration. Blood samples were collected from cubital vein before and after 6-week therapy with these drugs and once in the control group. Neutrophil superoxide anion generation in whole blood without and with opsonized zymosan (OZ) stimulation was determined using superoxide dismutase from bovine erythrocytes. In the atorvastatin group, statistically significant (P < 0.05) decrease in superoxide anion generation by nonstimulated and OZ-stimulated neutrophils was observed after 6 weeks of therapy. In fluvastatin group, no changes in neutrophil superoxide anion generation were observed after the 6-week treatment period. Our study has shown an additional nonlipid mechanism of atorvastatin used in CHD primary prevention.

Fluvastatin attenuates nitrate tolerance in patients with ischemic heart disease complicating hypercholesterolemia

BACKGROUND

Long-term administration of nitrates results in the development of tolerance. Nitrate tolerance is considered to occur in association with oxidative stress, although its underlying mechanisms are multi-factorial. Fluvastatin, a newly developed statin, is considered to have not only a cholesterol-lowering effect but also anti-oxidative properties.

METHODS

In this study, the effect of fluvastatin on nitrate tolerance was investigated in 12 dyslipidemic patients (nine men and three women, aged 63.5+/-6.7 years), who were complicated with ischemic heart disease and had received organic nitrates for a long period.

RESULTS

Four months after fluvastatin therapy, symptoms of angina were significantly reduced. Consumption of sublingual nitrates over 2 weeks significantly decreased (14.4+/-11.2 to 2.3+/-2.5 tablets, P<0.01). In exercise stress testing, exercise duration was significantly prolonged (275+/-73 to 360+/-86 s, P<0.01) and the blood pressure-heart rate products significantly increased (16368+/-2246 to 18381+/-1772, P<0.01). Both the percent change in forearm blood flow with reactive hyperemia (232+/-83 to 282+/-104%, P<0.05) and that after sublingual nitroglycerine (2.5+/-4.7 to 5.8+/-4.7%, P<0.05) were increased. Although the levels of total cholesterol, triglyceride, HDL-cholesterol, and LDL-cholesterol were unchanged, the serum anti-Ox-LDL titer (16.7+/-6.3 to 13.4+/-5.4 AcU/ml, P<0.05) and 8-OHdG level (1.11+/-0.34 to 0.73+/-0.34 ng/ml, P<0.05) decreased.

CONCLUSIONS

Fluvastatin attenuated nitrate tolerance in dyslipidemic patients complicated with ischemic heart disease who had been receiving organic nitrates over long period. The anti-oxidative effect of fluvastatin may attenuate nitrate tolerance.

Lipid-lowering therapy with fluvastatin inhibits oxidative modification of low density lipoprotein and improves vascular endothelial function in hypercholesterolemic patients

This prospective randomized trial was designed to elucidate clinically the effect of fluvastatin on inhibiting oxidation of the low density lipoprotein (LDL) and improving the vascular endothelial function as well as its lipid-lowering effects, in comparison with pravastatin. Of 64 consecutive dyslipidemic patients, 40 patients, whose level of total cholesterol or LDL-cholesterol maintained the criteria of the hypercholesterolemia in spite of 12-week dietary therapy, were randomly assigned to receive either fluvastatin (n=20) or pravastatin (n=20). We assessed the titer of antibody against oxidized LDL (anti-Ox-LDL) as a biomarker for LDL-oxidation, and the forearm blood flow response during reactive hyperemia by venous occlusion plethysmography, which indicates the endothelium-dependent vasodilator capacity. After the 16-week lipid-lowering therapy, the anti-Ox-LDL titer significantly decreased in the fluvastatin group (P<0.01) but did not change in the pravastatin group. The percent increase in the forearm blood flow at the peak reactive hyperemia from the baseline value (%RH) significantly increased in the fluvastatin group (P<0.001) but did not change in the pravastatin group. The ratio of the %RH after the therapy over the baseline value negatively correlated with that of the anti-Ox-LDL titer (R=0.73, P<0.001) in all patients. Fluvastatin may serve as an ideal drug for reducing the risk of atherosclerosis, not only by its cholesterol-lowering effect but also by its unique effects of inhibiting LDL oxidation and improving the vascular endothelial function.

Fluvastatin reduces modification of low-density lipoprotein in hyperlipidemic rabbit loaded with oxidative stress

The in vivo antioxidant effect of fluvastain, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, was investigated using Watanabe heritable hyperlipidemic (WHHL) rabbits subjected to nicotine-free cigarette smoke extracts as oxidative stress. Fluvastatin was given orally at doses of 10 and 30 mg/kg per day for 5 months. The cigarette smoke extracts were prepared by bubbling the gas phase of smoke into phosphate-buffered saline and was injected daily into the rabbit ear vein. The rabbits chronically treated with the cigarette smoke extracts showed an increase in plasma lipid peroxide levels, estimated as thiobarbituric acid-reactive substances. Oxidative modification of plasma low-density lipoprotein (LDL) was assessed by anion-exchange high-performance liquid chromatographic analysis, LDL susceptibility to oxidation, LDL incorporation into macrophages and thiobarbituric acid-reactive substances levels in LDL. Treatment with fluvastatin significantly reduced these effects induced by the cigarette smoke extracts in a dose-related manner and exerted a cholesterol-lowering effect. At the end of the experiment, the cigarette smoke extracts caused accumulation of cholesteryl ester in the thoracic aorta, while fluvastatin significantly prevented this accumulation. These results indicate that fluvastatin can exert an antioxidant effect in vivo, with a strong effect on oxidative stress such as smoking, a major risk factor of atherosclerosis.

Stereoselective analysis of fluvastatin in human plasma for pharmacokinetic studies

Fluvastatin, an inhibitor of cholesterol biosynthesis, is commercialized as a racemic mixture of the (+)-3R,5S and (-)-3S,5R stereoisomers, although inhibition of HMG-CoA reductase mainly resides in the (+)-(3R,5S)-fluvastatin isomer. The aim of the present study was to analyze fluvastatin isomers in human plasma with application to studies on kinetic disposition. Plasma samples of 1 ml were eluted into 3 ml LC-18 Supelclean (Supelco) columns equilibrated with methanol and water. The columns were washed with water and acetonitrile and then eluted with methanol containing 0.2% diethylamine. The (+)-3R,5S and (-)-3S,5R isomers were separated by HPLC on a Chiralcel OD-H chiral phase column and detected by fluorescence (lambda(ex) 305 nm; lambda(em) 390 nm). The quantification limit was 0.75 ng for each isomer/ml plasma and linearity was observed up to 625 ng/ml. The relative standard deviations obtained for intra- and inter-assay precision were lower than 10% and the recovery was higher than 80% for both enantiomers. Application of the method to a stereoselective study on the pharmacokinetics of fluvastatin administered as a single oral dose (Lescol, 20 mg) to a healthy volunteer revealed stereoselectivity, with the highest plasma concentrations being observed for the (-)-3S,5R isomer (Cmax 92.4 vs. 60.3 ng/ml, AUC(0-infinity) 133.3 vs. 97.4 ng h/ml, Cl/f 150.2 vs. 205.2 l h(-1) and Vd/f 4.4 vs. 6.0 l/kg).

Fluvastatin depresses the enhanced lipid peroxidation in vitamin E-deficient hamsters

Fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, has recently been reported to have the antioxidative activity in vitro. However, it is still unclear whether chronic treatment with this drug actually leads to amelioration of the redox status in the body. In this study, we investigated the antioxidative effect of fluvastatin in vivo, using a vitamin E-deficient hamster model, an in vivo model of enhanced oxidative stress. After pre-treatment with a vitamin E-deficient diet for 2 months, fluvastatin, pravastatin or probucol was added to the diet for 1 month. Vitamin E deficiency caused a significant increase in the levels of plasma oxidative stress markers such as 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) and hydroperoxides. Furthermore, there was a significant increase in the oxidizability of plasma lipids in the vitamin E-deficient animals, indicating that the oxidative stress was increased in the circulation. Fluvastatin markedly depressed the above oxidative stress markers in plasma, and significantly decreased the oxidizability of plasma lipids without affecting their levels. Probucol, a reference antioxidant, also showed a similar effect while pravastatin, another HMG-CoA reductase inhibitor, showed only a weak improvement. We suggest that the treatment with fluvastatin leads to a reduction of oxidative stress in vivo, which is mainly derived from its antioxidative property rather than its lipid-lowering activity.

Effects of fluvastatin and its major metabolites on low-density lipoprotein oxidation and cholesterol esterification in macrophages

We investigated effects of fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and its major metabolites, M2 and M4, on CuSO4-induced low-density lipoprotein (LDL) oxidation and cholesteryl ester accumulation in mouse peritoneal macrophages. All the test compounds inhibited LDL oxidation, and M2 had the most potent effect comparable to vitamin E. When LDL was previously incubated with the test compounds in the presence of CuSO4, the pre-treatment resulted in a marked reduction of facilitated cholesteryl ester accumulation in macrophages. Supplementation of mevalonate did not overcome the inhibitory effects of fluvastatin and its metabolites on both LDL oxidation and facilitated cholesterol esterification. Pravastatin, another HMG-CoA reductase inhibitor, did not show any inhibitory effect. Consequently, these effects of fluvastatin and its metabolites are considered to be derived from their own unique chemical structures. Moreover, fluvastatin and M2 directly inhibited cholesterol esterification induced by oxidized LDL in macrophages, but pravastatin was also found to have a weak effect. As their inhibitory effects were overcome by addition of mevalonate, the direct inhibitory effect on cholesterol esterification would be a common property of HMG-CoA reductase inhibitors. The inhibitory effects of fluvastatin and its metabolites on both LDL oxidation and cholesterol esterification in macrophages may contribute to the antiatherogenic action in vivo.

Immunological response to oxidized LDL occurs in association with oxidative DNA damage independently of serum LDL concentrations in dyslipidemic patients

Oxidative modification of LDL induces immunogenic epitopes in the LDL molecule, and the presence of antibodies against oxidized LDL (anti-Ox-LDL) has been demonstrated in human sera. However, little is known about the clinical significance of anti-Ox-LDL. To elucidate a clinical relationship between the immunological response to oxidized LDL and cellular oxidative stress, we measured serum titers of anti-Ox-LDL in 45 unselected patients with hypercholesterolemia and serum 8-hydroxy-2'-deoxyguanosine (8-OHdG), considered a biomarker of the oxidative damage to DNA. The anti-Ox-LDL titer was not correlated with the serum LDL-C concentration, but was correlated with the 8-OHdG concentration (r = 0.300, P < 0.05) in a simple linear regression. Multiple regression analysis indicated that 8-OHdG was independently correlated with anti-Ox-LDL (r = 0.429, P < 0.05), but no other variables, including LDL-C concentrations and smoking habit, were correlated with anti-Ox-LDL. In 16 subgroup patients, the concentrations of TC, TG and LDL-C decreased and the HDL-C concentration increased after cholesterol-lowering therapy with fluvastatin. In addition, both the anti-Ox LDL titer (14.0 +/- 9.5 to 11.4 +/- 6.6 AcU/ml, P < 0.05) and the 8-OHdG concentration (1.19 +/- 0.41 to 0.85 +/- 0.43 ng/ml, P < 0.05) also decreased after fluvastatin therapy. The immunological response to LDL oxidation on vascular wall tissues or cells appear to occur in association with oxidative DNA damage. The measurement of anti-Ox-LDL may be a useful indicator for lipid-lowering therapy.

Protective effect of fluvastatin on degradation of apolipoprotein B by a radical reaction in human plasma

Fluvastatin, which is a synthetic 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase inhibitor, its metabolites (M2, M3 and M4) and trolox all inhibited the decrease of apolipoprotein B-100 (apoB) and alpha-tocopherol in a radical reaction of human plasma initiated by Cu2+. The concentrations of fluvastatin, M2, M3, M4 and trolox for 50% inhibition (IC50) of apoB fragmentation were 405, 8.55, 1.75, 305, and 43.4 microM, respectively. The IC50 value of pravastatin, which is another HMG-CoA reductase inhibitor, was 2880 microM, showing that pravastatin is not an effective antioxidant. Although fluvastatin, its metabolites and trolox inhibited the decrease of alpha-tocopherol in a similar manner to that of apoB, pravastatin did not significantly inhibit the decrease of alpha-tocopherol. Since oxidation of low density lipopotein (LDL) is an important step in the initiation and progression of atherosclerosis, fluvastatin may reduce the risk of atherosclerosis not only by lowering plasma cholesterol but also by protecting LDL from oxidation.