Simvastatin enhances the regeneration of endothelial cells via VEGF secretion in injured arteries.

Kozawa O.

Department of Pharmacology, Gifu University School of Medicine, Gifu, Japan. leuven cc.gifu-u.ac.jp

The search for a novel therapy for endothelial regenerating is an area of intensive investigation. Recent experimental and clinical evidence strongly suggests that 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors (statins) have several physiological effects independent of low-density lipoprotein cholesterol reduction. We here report that the carotid arterial blood flow after endothelial injury in hamsters treated with simvastatin was restored, in contrast to the situation in nontreated hamsters. Histologic observations showed a prompt recovery of endothelial cells with a much higher DNA synthesis index in repaired endothelium of hamsters treated with simvastatin. The amount of secreted vascular endothelial cell growth factor (VEGF) by cultured vascular smooth muscle cells from hamsters treated with simvastatin was significantly increased. Mevalonate reduced the amount of VEGF secretion by simvastatin in vitro. Finally, an injection of either an anti-VEGF antibody or an anti-VEGF receptor-1 (Flt-1) antibody, but not anti-VEGF receptor-2 (Flk-1), reduced the prompt endothelial healing. Simvastatin regulates endothelial regenerating by an over-release of VEGF and by this may result in prompt endothelial healing after vascular injury. Our results provide new insights into the role of statin and VEGF in the pathogenesis of vascular diseases.

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Relative lipophilicities, solubilities, and structure-pharmacological considerations of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors pravastatin, lovastatin, mevastatin, and simvastatin.

Mahoney EM.

Bristol-Myers Squibb Pharmaceutical Research Institute, New Brunswick, NJ 08903.

The apparent octanol-water partition coefficients (Po/w) and aqueous solubilities for four 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors [pravastatin, lovastatin (mevinolin), mevastatin (compactin), and simvastatin (synvinolin)] were compared. Pravastatin is highly hydrophilic compared with lovastatin, mevastatin, or simvastatin. Pravastatin is clinically used as the active hydroxy acid, while the other three compounds are administered as prodrug lactones which, over a period of time, convert in vivo to their respective active hydroxy acid forms. The order of the Po/w values of the hydroxy acid forms was pravastatin much less than mevastatin less than lovastatin less than simvastatin at each pH evaluated, with approximate ratios of 1:25:75:200, respectively. The relative order and the ratios of partition coefficients for the lactone forms were similar to those for the hydroxy acid forms. In addition, lovastatin, mevastatin, and simvastatin are virtually insoluble in water, with solubility values ranging from 0.0013 to 0.0015 mg/mL at 23 degrees C. In comparison, pravastatin is hydrophilic, as demonstrated by the greater than 100-fold greater solubility of its lactone form (0.18 mg/mL). The greater hydrophilicity of pravastatin may explain its reported lower permeation into nonhepatic cells and the selectivity with respect to inhibition of cholesterol synthesis.

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The influence of simvastatin on adrenal corticosteroid production and urinary mevalonate during adrenocorticotropin stimulation in patients with heterozygous familial hypercholesterolemia.

Illingworth DR.

Department of Medicine, Oregon Health Sciences University, Portland 97201.

The adrenal gland requires a continuous supply of cholesterol for the biosynthesis of adrenal corticosteroids, which can be supplied by low density lipoprotein receptor-mediated uptake or local synthesis. The present study examined whether hypolipidemic therapy with a potent HMG CoA reductase inhibitor, simvastatin, compromises the adrenal response to ACTH stimulation in adult patients with heterozygous familial hypercholesterolemia. The adrenal response to a 36-h continuous ACTH infusion was determined at baseline and after 2 months of simvastatin treatment (40 mg, twice daily) in eight patients. Simvastatin reduced total and low density lipoprotein cholesterol levels by 36% and 45%, respectively. The time course of the increase in serum cortisol concentrations with continuous ACTH infusion was the same before and during simvastatin therapy, as were the rates of urinary excretion of free cortisol, 17-hydroxycorticosteroids, and 17-ketosteroids. Urinary excretion of mevalonate, which correlates with rates of whole body cholesterol synthesis, decreased from 3.8 +/- 0.42 (+/- SEM) mu,ol/24 h at baseline to 2.75 +/- 0.56 on simvastatin; no significant changes were seen in the urinary mevalonate levels before and after simvastatin therapy during ACTH stimulation. We conclude that the hypolipidemic effects of simvastatin in patients with heterozygous familial hypercholesterolemia are paralleled by a decrease in urinary mevalonate, but that the drug does not adversely affect ACTH-stimulated adrenal corticosteroid production.

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Simvastatin treatment restores vasoconstriction and the inhibitory effect of LPC on endothelial relaxation via affecting oxidizing metabolism in diabetic rats.

Ozansoy G.

Department of Pharmacology, Faculty of Pharmacy, Ankara University, Ankara, Turkey.

Oxidative stress and dyslipidaemia play an important role in the development of diabetes-induced vascular complications. The aim of this study was to examine the reversal effects of simvastatin on some metabolic and oxidative parameters, and vascular functions in diabetic rats. Diabetes was induced by a single injection of streptozotocin (STZ, 45 mg/kg, i.p.). Eight weeks after STZ induction, some of the diabetic and control rats were treated with simvastatin (10 mg/kg rat/d) for 4 weeks. Plasma glucose, triglyceride and total cholesterol concentrations were significantly increased in 12-week diabetic rats. Simvastatin treatment stopped the loss of body weight, completely normalized the increase of plasma lipids and partially reduced the hyperglycaemia in diabetic rats. Increased malondialdehyde levels, catalase and glutathione peroxidase activities were normalised by simvastatin treatment in diabetic aorta. Phenylephrine (PE)-induced contractility in aorta rings was unaffected by diabetes, but was markedly decreased after simvastatin treatment in both control and diabetic rats. Reduction of endothelium-dependent vasorelaxation in diabetes was significantly ameliorated by simvastatin treatment. Incubation of aorta rings with lysophosphatidylcholine, a component of the oxidized LDL, did not significantly affect PE-induced contractions, but reduced endothelium-dependent relaxations more in untreated-diabetic rats than in other experimental groups. The endothelium-independent vasorelaxations were similar in all ring preparations. These results indicate that simvastatin treatment may ameliorate diabetes-induced abnormal vasoconstriction and endothelial dysfunction via affecting general and oxidizing metabolism, nitric oxide disability and intracellular calcium mobilisation.

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Long-term effects of simvastatin in familial dysbetalipoproteinaemia.

Stalenhoef AF.

Department of Medicine, University Hospital Nijmegen, The Netherlands.

The long-term effects (66 weeks) of simvastatin (40 mg in one or two doses per day), an inhibitor of HMG CoA-reductase, were evaluated in 12 patients with familial dysbetalipoproteinaemia (type III hyperlipoproteinaemia). Simvastatin had a persistent hypolipidaemic effect; the mean reduction in serum cholesterol was 36-51%, and the mean reduction in serum triglycerides was 32-55%. The decrease in serum lipids was caused by a decline in VLDL-cholesterol and LDL-cholesterol levels; the mean ratio between VLDL-cholesterol and serum triglycerides decreased significantly from 1.06 to 0.73. There was no significant difference between the once-a-day and twice-a-day regimens. Simvastatin was well tolerated; no serious side-effects were observed. These data demonstrate the usefulness of simvastatin in the therapy of familial dysbetalipoproteinaemia.

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Hypercholesterolaemia: simvastatin and pravastatin alter cholesterol metabolism by different mechanisms.

Tomkin GH.

Royal College of Surgeons, Dublin, Ireland.

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor simvastatin, reduced low-density-lipoprotein (LDL) cholesterol in hypercholesterolaemic patients by 40% (P less than 0.001). The reduction in LDL cholesterol was accompanied by a significant decrease in the esterified/free cholesterol ratio of the patients' LDL from 2.51 +/- 0.13 to 2.06 +/- 0.14 (P less than 0.01). This change led to a significant increase (P less than 0.05) in the capacity of the LDL to suppress [14C]acetate incorporation into cholesterol in mononuclear leucocytes. Furthermore, [14C]acetate incorporation into the patients mononuclear leucocytes was significantly lower (P less than 0.02) following drug treatment (117 +/- 22 vs. 162 +/- 29 nmol/mg cell protein). Comparison of simvastatin with another HMG-CoA reductase inhibitor pravastatin, showed similar reduction in LDL cholesterol. Pravastatin treatment however, did not result in a reduction in the LDL esterified/free cholesterol ratio or in the changes in cellular cholesterol synthesis and its regulation by LDL which accompanied simvastatin treatment. The activity of the enzyme acyl-coenzyme A: cholesterol acyltransferase (ACAT) in patients' mononuclear cells remained unchanged after treatment with either drug. Results of the study show that while the drugs are equally effective in lowering LDL cholesterol, simvastatin has additional compositional effects on LDL which increase its capacity to regulate mononuclear leucocyte cholesterologenesis.

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