Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: UNIPROT:Q8NEX9 (reductase)
26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Atorvastatin is a second generation synthetic statin, introduced in Belgium in May 1998. Its mechanism of action is similar to that of the other statins, i.e. the inhibition of HMG Co-A reductase, the key enzyme in cholesterol synthesis, which leads to the increase of LDL receptors. The prolonged half-life (20-30 H) of atorvastatin and its active metabolites, induces a prolonged inhibition of HMG Co-A reductase and a reduction of hepatitic apo B production. The biological efficacy of atorvastatin is high: 41 to 61% lowering of LDL depending of the dose. Atorvastatin is indicated in primary hypercholesterolemia, mixed hyperlipidemia and homozygous familial hypercholesterolemia. If necessary, a resin or even a fibrate may be added. The safety profile is good. The most common adverse effects are gastro-intestinal and transient. Liver tests or muscle enzymes are rarely modified. If clinical proof of reduction of CV morbidity and mortality in primary and secondary prevention is obtained, atorvastatin shall represent a major step forward in the treatment of hypercholesterolemia.
...
PMID:[Atorvastatin (Lipitor)]. 1058 78

Combined hyperlipidemia (CHL) is characterized by a concomitant elevation of plasma levels of triglyceride-rich, very low density lipoproteins (VLDLs) and cholesterol-rich, low density lipoproteins (LDLs). The predominance of small, dense LDLs contributes significantly to the premature development of coronary artery disease in patients with this atherogenic dyslipoproteinemia. In the present study, we evaluated the impact of atorvastatin, a newly developed inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase, on the cholesteryl ester transfer protein (CETP)-mediated remodeling of apolipoprotein (apo) B-containing lipoprotein subspecies, and more specifically, the particle subpopulations of VLDL and LDL in CHL. In parallel, we evaluated the atorvastatin-induced modulation of the quantitative and qualitative features of atherogenic apo B-containing and cardioprotective apo AI-containing lipoprotein subspecies. Atorvastatin therapy (10 mg/d for a 6-week period) in patients with a lipid phenotype typical of CHL (n=18) induced reductions of 31% (P<0.0001) and 36% (P<0.0001) in plasma total cholesterol and LDL cholesterol, respectively. In addition, atorvastatin significantly reduced VLDL cholesterol, triglycerides, and apo B levels by 43% (P<0.0001), 27% (P=0.0006), and 31% (P<0.0001), respectively. The plasma concentrations of triglyceride-rich lipoproteins (VLDL1, Sf 60 to 400; VLDL2, Sf 20 to 60; and intermediate density lipoproteins, Sf 12 to 20) and of LDL, as determined by chemical analysis, were markedly diminished after drug therapy (-30% and -28%, respectively; P<0.0007). Atorvastatin significantly reduced circulating levels of all major LDL subspecies, ie, light (-28%, P<0.0008), intermediate (-27%, P<0.0008), and dense (-32%, P<0.0008) LDL; moreover, in terms of absolute lipoprotein mass, the reduction in dense LDL levels (mean -62 mg/dL) was preponderant. In addition, the reduction in plasma dense LDL concentration after therapy was significantly correlated with a reduction in plasma VLDL1 levels (r=0.429, P=0.0218). Atorvastatin induced a significant reduction (-7%, P=0.0039) in total CETP-dependent CET activity, which accurately reflects a reduction in plasma CETP mass concentration. Total CETP-mediated CET from high density lipoproteins to apo B-containing lipoproteins was significantly reduced (-26%, P<0.0001) with drug therapy. Furthermore, CETP activity was significantly correlated with the atorvastatin-induced reduction in plasma VLDL1 levels (r=0.456, P=0. 0138). Indeed, atorvastatin significantly and preferentially decreased CET from HDL to the VLDL1 subfraction (-37%, P=0.0064), thereby reducing both the levels (-37%, P=0.0001) and the CE content (-20%, P<0.005) of VLDL1. We interpret our data to indicate that 2 independent but complementary mechanisms may be operative in the atorvastatin-induced reduction of atherogenic LDL levels in CHL: first, a significant degree of normalization of both the circulating levels and the quality of their key precursors, ie, VLDL1, and second, enhanced catabolism of the major LDL particle subclasses (ie, light, intermediate, and dense LDL) due to upregulation of hepatic LDL receptors.
...
PMID:Action of atorvastatin in combined hyperlipidemia : preferential reduction of cholesteryl ester transfer from HDL to VLDL1 particles. 1063 17

BACKGROUND: Coronary heart disease (CHD) is the number one cause of death in Western societies. Elevated levels of plasma low-density lipoprotein (LDL) cholesterol and triglycerides (TG) increase the risk for CHD. 3-Hydroxy-3-methylglutaryl conenzyme A (HMG-CoA) reductase inhibitors effectively reduce plasma cholesterol levels in patients with hypercholesterolemia. This study assesses the safety and dose-related effects of atorvastatin calcium on lipoprotein fractions in patients with LDL cholesterol levels between 160 mg/dL (4.1 mM) and 250 mg/dL (6.5 mM) or less and TG levels of 400 mg/dL (4.5 mM) or less. METHODS AND RESULTS: Sixty-five patients were enrolled in a 6-week, randomized, placebo-controlled, parallel-group study. Patients received placebo or atorvastatin 10, 20, 40, 60, or 80 mg once daily. Adjusted mean decreases in LDL cholesterol for patients receiving atorvastatin 10, 20, 40, 60, and 80 mg were 37%, 42%, 50%, 52%, and 59%, respectively, compared with a mean increase of 0.3% for patients receiving placebo; the differences between each of the atorvastatin dose groups and placebo were statistically significant (P =.0001). Total cholesterol, triglycerides, and apolipoprotein B were significantly reduced in atorvastatin groups (P =.0001). Adverse events were similar in the placebo and atorvastatin treatment groups. No patient had a serious adverse event or withdrew because of an adverse event during this study. CONCLUSIONS: Atorvastatin effectively lowered plasma LDL cholesterol, triglycerides, and apoB levels in a dose-related manner. Atorvastatin was well tolerated in hyperlipidemic patients over a 6-week period.
...
PMID:A Multicenter, Placebo-Controlled, Dose-Ranging Study of Atorvastatin. 1068 89

Atorvastatin is a new hepatic hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitor that has been demonstrated to be efficacious in reducing both triglyceride (TG) and cholesterol (CHOL) levels in humans. Twenty-seven (N = 27) patients with primary hypertriglyceridemia (TG > 350 mg/dL) were studied before and after 4 weeks on atorvastatin treatment at a dosage of either 20 (n = 16) or 80 (n = 11) mg/d. The present report examines changes in the plasma levels of several apolipoproteins, including apolipoprotein C-II (apoC-II), apoC-III, and apoE, after atorvastatin. Dose-dependent reductions in both CHOL (20.3% v 43.1%) and TG (26.5% v 45.8%) for the low and high dose, respectively, have been reported in these individuals. In addition to the reductions in apoB commonly associated with the use of HMG-CoA reductase inhibitors, significant reductions in apoE (37% and 49%), apoC-II (28% and 42%), and apoC-III (18% and 30%) were observed with this agent at the 20- and 80-mg/d dosage, respectively. Using fast protein liquid chromatography (FPLC) to fractionate whole plasma according to particle size, the effect of atorvastatin on lipid and apolipoprotein distribution in 20 lipoprotein fractions was also determined. Our results indicate that after 4 weeks on atorvastatin, (1) there was a 2-fold increase in the CHOL content as assessed by the CHOL/apoB ratio for 13 subfractions from very-low-density lipoprotein (VLDL) to small low-density lipoprotein (LDL); (2) there was a statistically significant reduction in the percentage of plasma apoB associated with VLDL-sized particles (30.5% v 26.8%); (3) there was a preferential reduction in plasma apoE from non-apoB-containing lipoproteins with treatment; (4) the losses of apoC-II and apoC-III, on the other hand, were comparable for all lipoprotein fractions; and (5) the fraction of plasma TG associated with HDL was increased after treatment. These changes in lipids and apolipoproteins did not depend on the dose of atorvastatin. There was, on the other hand, a dose-dependent reduction in cholesteryl ester transfer protein (CETP) activity, defined as the percentage of 3H-cholesteryl oleate transferred from high-density lipoprotein (HDL) to LDL. CETP activity was reduced by 10.3% and 26.4% with the low and high dose of atorvastatin. Together, these composition data would be consistent with a net reduction in the number of TG-rich lipoproteins that may be explained by (1) a reduction in VLDL synthesis, (2) a preferential removal of VLDL without conversion to LDL, and (3) a preferential accelerated removal of a subpopulation of LDL.
...
PMID:Lipid and apolipoprotein levels and distribution in patients with hypertriglyceridemia: effect of triglyceride reductions with atorvastatin. 1069 Sep 40

Elevated levels of serum lipids and lipoproteins are known to play a major role in the development of atherosclerosis and subsequent coronary heart disease (CHD). In controlled clinical studies, atorvastatin (Sortis), a new 3-hydroxy-3-methyl-glutaryl-coenzyme-A (HMG-CoA)-reductase inhibitor, proved to be a very effective and safe lipid-lowering agent. The aim of this open-label, multicentre study (without a control group) was to confirm the efficacy and safety of atorvastatin in a private practice group, including 181 Swiss cardiologists, internists, and general practitioners. A total of 877 hyperlipidaemic patients requiring treatment participated in this study. To evaluate the effectiveness of the treatment with atorvastatin over a period of 12 weeks, total plasma cholesterol (TC), HDL cholesterol, LDL cholesterol and triglycerides (TG) were determined every 4 weeks. The initial atorvastatin dose was 10 mg in 78% of patients and 20 mg in 22%. The dose was doubled every 4 weeks until the target values of TC < or = 5.2 mmol/l and TC/HDL < or = 5 were reached. After 12 weeks of treatment with atorvastatin the mean reduction in TC, TC/HDL, LDL and TG compared to baseline levels was 33, 37, 42, and 25% respectively. At the same time the HDL concentration was increased by 9%. These results were evidenced in patients with existing coronary heart disease, in high risk patients without manifest coronary heart disease and in patients with significantly elevated lipid levels (TC > 7.8 mmol/l, TC/HDL > 6.5). After treatment with atorvastatin for 12 weeks, 59% of patients had reached the therapeutic target of TC < or = 5.2 mmol/l. The target of TC/HDL < or = 5 was reached by 79%. Atorvastatin was almost without exception well tolerated, the most frequently reported side effects being nausea, myalgia, and headache. In this open-label multicentre study atorvastatin was found to be effective and well tolerated. The observed reduction in the lipid and lipoprotein concentration is in accordance with the results of published controlled studies. The lipid and lipoprotein concentrations were decreased significantly in patients with slight to moderate elevation of lipid levels as well as in those with significantly raised values.
...
PMID:[Evaluating the efficacy and tolerance of atorvastatin in hyperlipidemia in general practice (SWITCH Study)]. 1089 90

The underlying disorder in the vast majority of cases of cardiovascular disease is atherosclerosis, for which low-density lipoprotein cholesterol is recognized as a major risk factor. Data from epidemiologic studies have suggested that lower cholesterol levels are associated with a lower overall risk of morbidity and mortality due to coronary heart disease. Numerous clinical trials with lipid-lowering agents support these epidemiologic data. Of these, studies with the HMG-CoA (3-hydroxy 3-methylglutaryl coenzyme A) reductase inhibitors, or statins, have shown the greatest lipid-lowering effects. Data from recent trials such as the Atorvastatin Versus Revascularization Treatment contribute to a growing body of evidence that suggests that aggressive reduction of cholesterol can yield additional clinical benefits above and beyond that observed with less robust treatment regimens. Aggressive cholesterol-lowering strategies have the potential therefore to have a significant impact on levels of atherosclerotic disease throughout the westernized world. Such effects argue in favor of renaming the entire class of drugs as anti- atherosclerotic rather than lipid-lowering agents.
...
PMID:Implications of the atorvastatin versus revascularization treatment (AVERT) study for the clinician. 1098 Sep 11

The availability of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has revolutionised the treatment of lipid abnormalities in patients at risk for the development of coronary atherosclerosis. The relatively widespread experience with HMG-CoA therapy has allowed a clear picture to emerge concerning the relative tolerability of these agents. While HMG-CoA reductase inhibitors have been shown to decrease complications from atherosclerosis and to improve total mortality, concern has been raised as to the long term safety of these agents. They came under close scrutiny in early trials because ocular complications had been seen with older inhibitors of cholesterol synthesis. However, extensive evaluation demonstrated no significant adverse alteration of ophthalmological function by the HMG-CoA reductase inhibitors. Extensive experience with the potential adverse effect of the HMG-CoA reductase inhibitors on hepatic function has accumulated. The effect on hepatic function for the various HMG-CoA reductase inhibitors is roughly dose-related and 1 to 3% of patients experience an increase in hepatic enzyme levels. The majority of liver abnormalities occur within the first 3 months of therapy and require monitoring. Rhabdomyolysis is an uncommon syndrome and occurs in approximately 0.1% of patients who receive HMG-CoA reductase inhibitor monotherapy. However, the incidence is increased when HMG-CoA reductase inhibitors are used in combination with agents that share a common metabolic path. The role of the cytochrome P450 (CYP) enzyme system in drug-drug interactions involving HMG-CoA reductase inhibitors has been extensively studied. Atorvastatin, cerivastatin, lovastatin and simvastatin are predominantly metabolised by the CYP3A4 isozyme. Fluvastatin has several metabolic pathways which involve the CYP enzyme system. Pravastatin is not significantly metabolised by this enzyme and thus has theoretical advantage in combination therapy. The major interactions with HMG-CoA reductase inhibitors in combination therapy involving rhabdomyolysis include fibric acid derivatives, erythromycin, cyclosporin and fluconazole. Additional concern has been raised relative to overzealous lowering of cholesterol which could occur due to the potency of therapy with these agents. Currently, there is no evidence from clinical trials of an increase in cardiovascular or total mortality associated with potent low density lipoprotein reduction. However, a threshold effect had been inferred by retrospective analysis of the Cholesterol and Recurrent Events study utilising pravastatin and the role of aggressive lipid therapy is currently being addressed in several large scale trials.
...
PMID:Comparative tolerability of the HMG-CoA reductase inhibitors. 1100 3

In an in vitro study, we compared the cytochrome P450 (CYP)-dependent metabolism and drug interactions of the acid and lactone forms of the 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor atorvastatin. Metabolism of atorvastatin acid and lactone by human liver microsomes resulted in para-hydroxy and ortho-hydroxy metabolites. Both substrates were metabolized mainly by CYP3A4 and CYP3A5. Atorvastatin lactone had a significantly higher affinity to CYP3A4 than the acid (K(m): para-hydroxy atorvastatin, 25.6 +/- 5.0 microM; para-hydroxy atorvastatin lactone, 1.4 +/- 0.2 microM; ortho-hydroxy atorvastatin, 29.7 +/- 9.4 microM; and ortho-hydroxy atorvastatin lactone, 3.9 +/- 0.2 microM). Compared with atorvastatin acid, CYP-dependent metabolism of atorvastatin lactone to its para-hydroxy metabolite was 83-fold higher [formation CL(int) (V(max)/K(m)): lactone 2949 +/- 3511 versus acid 35.5 +/- 48.1 microl. min(-1). mg(-1)] and to its ortho-hydroxy metabolite was 20-fold higher (CL(int): lactone 923 +/- 965 versus acid 45.8 +/- 59. 1 microl. min(-1). mg(-1)). Atorvastatin lactone inhibited the metabolism of atorvastatin acid by human liver microsomes with an inhibition constant (K(i)) of 0.9 microM while the K(i) for inhibition of atorvastatin by atorvastatin lactone was 90 microM. Binding free energy calculations of atorvastatin acid and atorvastatin lactone complexed with CYP3A4 revealed that the smaller desolvation energy of the neutral lactone compared with the anionic acid is the dominant contribution to the higher binding affinity of the lactone rather than an entropy advantage. Because atorvastatin lactone has a significantly higher metabolic clearance and the lactone is a strong inhibitor of atorvastatin acid metabolism, it can be expected that metabolism of the lactone is the relevant pathway for atorvastatin elimination and drug interactions. We hypothesize that most of the open acid metabolites present in human plasma are generated by interconversion of lactone metabolites.
...
PMID:Lactonization is the critical first step in the disposition of the 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor atorvastatin. 1103 66

The efficacy of atorvastatin, a new hydroxymethylglutaryl (HMG)-CoA reductase inhibitor, in reducing serum lipid levels, modifying lipoprotein composition, and suppressing cholesterol synthesis was evaluated in patients with homozygous familial hypercholesterolemia (homozygous FH) undergoing LDL-apheresis therapy. Atorvastatin was given in escalating doses (10, 20, and 40 mg/day) to nine patients with homozygous FH. Five of nine patients responded well to atorvastatin; four of these patients were receptor-defective and the remaining one was receptor-negative. The change in LDL-cholesterol in the receptor-defective patients averaged -20.6% compared to the baseline level at the highest dose of atorvastatin. Of five receptor-negative type patients, only one showed good response to atorvastatin therapy with a LDL-cholesterol reduction of 14.9%. Although the other four receptor-negative patients did not show a change in LDL-cholesterol, all of them exhibited a considerable increase in HDL-cholesterol. All patients showed reduced urinary excretion of mevalonic acid, suggesting that atorvastatin decreases LDL-cholesterol by inhibiting cholesterol biosynthesis even where LDL-receptor activity is not present. Atorvastatin also decreased serum triglycerides in both receptor-negative and defective patients, especially in the latter. As cholesterol level rebounds quickly after each apheresis procedure, a combination therapy using atorvastatin and apheresis may increase the efficacy of the apheresis treatment, improving cost-benefit effectiveness by reducing the frequency of the apheresis treatment.
...
PMID:The effect of atorvastatin on serum lipids and lipoproteins in patients with homozyous familial hypercholesterolemia undergoing LDL-apheresis therapy. 1105 3

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may exert pleiotropic effects on vascular cells independent of lowering plasma cholesterol. To elucidate the molecular mechanisms involved in these effects, we investigated the impact of statins on production of reactive oxygen species (ROS) in rat aortic vascular smooth muscle cells (VSMC). Exposure of VSMC to angiotensin II caused production of ROS via angiotensin AT1 receptor activation. Pretreatment with atorvastatin inhibited angiotensin II-induced ROS production. Atorvastatin decreased AT1 receptor mRNA levels in a time- and concentration-dependent manner and consistently reduced AT1 receptor density. L-Mevalonate but not hydroxy-cholesterol reversed the inhibitory effect of atorvastatin on AT1 receptor transcript levels. Inhibition of geranylgeranyl-transferase but not of farnesyl-transferase mimicked the effect of atorvastatin on AT1 receptor gene expression. Atorvastatin did not decrease AT1 receptor gene transcription but did reduce the half-life of the AT1 receptor mRNA. AT1 receptor activation by angiotensin II increased the expression of the GTPase rac1, enhanced rac1 GTP-binding activity, and increased the geranylgeranyl-dependent translocation of rac1 to the cell membrane. In contrast, statins inhibited rac1 activity and membrane translocation. Consequently, specific inhibition of rac1 with Clostridium sordellii lethal toxin blocked angiotensin II-induced production of free radicals. Finally, treatment of rats with atorvastatin caused down-regulation of aortic AT1 receptor mRNA expression and reduced aortic superoxide production in vivo. Cholesterol-independent down-regulation of AT1 receptor gene expression and inhibition of rac1, leading to decreased ROS production, demonstrates a novel regulatory mechanism of statins that may contribute to the beneficial effects of these drugs beyond lowering of plasma cholesterol.
...
PMID:Inhibition of geranylgeranylation reduces angiotensin II-mediated free radical production in vascular smooth muscle cells: involvement of angiotensin AT1 receptor expression and Rac1 GTPase. 1117 61


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---