Effects of an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase on serum lipoproteins and ubiquinone-10-levels in patients with familial hypercholesterolemia

Analysis of five HMG-CoA reductase inhibitors-- atorvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin: pharmacological, pharmacokinetic and analytical overview and development of a new method for use in pharmaceutical formulations analysis and in vitro metabolism studies

A specific, accurate, precise and reproducible high-performance liquid chromatographic (HPLC) method was developed and validated for the simultaneous quantitation of five 3-hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitors, viz. atorvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin, in pharmaceutical formulations and extended the application to in vitro metabolism studies of these statins. Ternary gradient elution at a flow rate of 1 mL/min was employed on an Intertisl ODS 3V column (4.6 x 250 mm, 5 microm) at ambient temperature. The mobile phase consisted of 0.01 m ammonium acetate (pH 5.0), acetonitrile and methanol. Theophylline was used as an internal standard (IS). The HMG-CoA reductase inhibitors and their metabolites were monitored at a wavelength of 237 nm. Drugs were found to be 89.6-105.6% of their label's claim in the pharmaceutical formulations. For in vitro metabolism studies the reaction mixtures were extracted with simple liquid-liquid extraction using ethyl acetate. Baseline separation of statins and their metabolites along with IS free from endogenous interferences was achieved. Nominal retention times of IS, atorvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin were 7.5, 17.2, 21.6, 28.5, 33.5 and 35.5 min, respectively. The proposed method is simple, selective and could be applicable for routine analysis of HMG-CoA reductase inhibitors in pharmaceutical preparations as well as in vitro metabolism studies.

Thematic review series: the pathogenesis of atherosclerosis. An interpretive history of the cholesterol controversy, part V: the discovery of the statins and the end of the controversy

The first four reviews in this series (Steinberg, D. 2004. J. Lipid Res. 45: 1583-1593; Steinberg, D. 2005. J. Lipid Res. 46: 179-190; Steinberg, D. 2005. J. Lipid Res. 46: 2037-2051; Steinberg, D. 2006. J. Lipid Res. 47: 1-14) traced the gradual accumulation of evidence, evidence of several different kinds, supporting the lipid hypothesis. They tracked the history from Anitschkow's 1913 classic work on the cholesterol-fed rabbit model to the breakthrough 1984 Coronary Primary Prevention Trial, the first large, randomized, double-blind primary intervention trial showing that decreasing blood cholesterol (using cholestyramine) significantly reduces coronary heart disease events. At that point, for the first time, decreasing blood cholesterol levels became an official national public health goal. Still, only a small fraction of patients at high risk were getting appropriate cholesterol-lowering treatment, and a number of important clinical questions remained unanswered. This final review in the series traces the early studies that led to the discovery of the statins and briefly reviews the now familiar large-scale clinical trials demonstrating their safety and their remarkable effectiveness in reducing coronary heart disease morbidity and mortality.

Efficacy of Colestimide Coadministered With Atorvastatin in Japanese Patients With Heterozygous Familial Hypercholesterolemia (FH)

BACKGROUND

Colestimide, a 2-methylimidazole-epichlorohydrin polymer, is a new bile-acid-sequestering resin, that is 4-fold as powerful at lowering low-density lipoprotein cholesterol (LDL-C) as the conventional resin (cholestyramine). Moreover, colestimide has excellent patient compliance because it is available in tablet form.

METHODS AND RESULTS

The clinical efficacy of colestimide coadministered with atorvastatin on lipid and apolipoprotein concentrations was examined in 15 patients (M/F=10/5, mean+/-SE age=54+/-9 years) with heterozygous familial hypercholesterolemia (FH). After a period of wash-out of any lipid-lowering drugs, atorvastatin (20-40 mg) was administered to patients for at least 8 weeks, and then 3 g of colestimide was administered for a further 8 weeks. Total and LDL-C significantly (<0.0001) decreased by 35% from 361 to 233 mg/dl and 41% from 274 to 161 mg/dl, respectively. Addition of colestimide caused a further significant 12% and 20% reduction, respectively, from the initial values to 205 and 129 mg/dl, respectively. Colestimide was also effective in reducing serum LDL-C concentrations in heterozygous FH patients with hypertriglyceridemia (triglycerides>or=150 mg/dl).

CONCLUSIONS

When monotherapy with atorvastatin is insufficient to treat severely hypercholesterolemic patients, such as those with heterozygous FH, colestimide acts to reinforce the action of statins.

Reduction of Serum Ubiquinol-10 and Ubiquinone-10 Levels by Atorvastatin in Hypercholesterolemic Patients

Reduction of serum cholesterol levels with statin therapy decreases the risk of coronary heart disease. Inhibition of HMG-CoA reductase by statin results in decreased synthesis of cholesterol and other products downstream of mevalonate, which may produce adverse effects in statin therapy. We studied the reductions of serum ubiquinol-10 and ubiquinone-10 levels in hypercholesterolemic patients treated with atorvastatin. Fourteen patients were treated with 10 mg/day of atorvastatin, and serum lipid, ubiquinol-10 and ubiquinone-10 levels were measured before and after 8 weeks of treatment. Serum total cholesterol and LDL-cholesterol levels decreased significantly. All patients showed definite reductions of serum ubiquinol-10 and ubiquinone-10 levels, and mean levels of serum ubiquinol-10 and ubiquinone-10 levels decreased significantly from 0.81 +/- 0.21 to 0.46 +/- 0.10 microg/ml (p < 0.0001), and from 0.10 +/- 0.06 to 0.06 +/- 0.02 microg/ml (p = 0.0008), respectively. Percent reductions of ubiquinol-10 and those of total cholesterol showed a positive correlation (r = 0.627, p = 0.0165). As atorvastatin reduces serum ubiquinol-10 as well as serum cholesterol levels in all patients, it is imperative that physicians are forewarned about the risks associated with ubiquinol-10 depletion.

Optimal management of hyperlipidemia in primary prevention of cardiovascular disease

Cardiovascular disease (CVD) in the developed countries continues to grow at an epidemic proportion. There are a significant number of young adults with no clinical evidence of CVD, but who have two or more risk factors that predispose them to CV events and death. Many of these risk factors are modifiable, and by controlling these factors, the CVD burden can be decreased significantly. Recent statistics have shown that, if all major forms of CVD were eliminated, the life expectancy would rise by almost 7 years. Hence it is imperative that primary prevention efforts should be initiated at a young age to avert decades of unattended risk factors. Hyperlipidemia has been linked to CVD almost a century ago. Since then various clinical trials have not only supported this link, but have also shown the CV benefits in aggressively treating patients with hyperlipidemia. In this generation, we have various therapeutic agents that are capable of reducing the elevated lipid levels. With drugs like statins, we are able to reduce the risk of CVD by about 30% and avoid major adverse events. Newer drugs are being researched and introduced in the treatment of hyperlipidemia in humans. These can be used in combination therapy resulting in optimal levels of lipids. The new National Cholesterol Education Program (NCEP)/Adult Treatment Panel III (ATP III) guidelines have come as a wake-up call to clinicians about primary prevention of CVD through strict lipid management and multifaceted risk management approach in the prevention of CVD.

Mevastatin inhibits ovarian theca-interstitial cell proliferation and steroidogenesis

OBJECTIVE

Statins reduce cardiovascular risks by improving hypercholesterolemia, reducing vascular smooth muscle proliferation, and ameliorating inflammation. Polycystic ovary syndrome (PCOS) is associated with increased cardiovascular risks and is characterized by ovarian theca-interstitial hyperplasia and hyperandrogenism. This study tested the hypothesis that mevastatin limits theca-interstitial proliferation and decreases steroidogenesis.

DESIGN

In vitro study.

SETTING

Academic laboratory.

PATIENT(S)

None.

INTERVENTION(S)

Effects of mevastatin on cultured theca-interstitial cells.

MAIN OUTCOME MEASURE(S)

Proliferation was evaluated by determination of DNA synthesis using thymidine incorporation assay and by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay. Production of P and T was determined by specific radioimmunoassays.

RESULT(S)

Mevastatin induced a profound concentration-dependent inhibition of DNA synthesis. At the highest concentration (30 microM), mevastatin inhibited DNA synthesis by 92%. Similarly, in the MTT proliferation assay, mevastatin induced a concentration-dependent decrease in cell number. Mevastatin decreased production of P (by up to 49%) and T (by up to 52%); these effects remained significant when the effect on cell culture protein content was accounted for.

CONCLUSION(S)

Mevastatin inhibits proliferation of theca-interstitial cells; it also inhibits P and T production independently of the effects on cell growth. These findings provide a foundation for studies evaluating statins as potential therapeutic agents in the treatment of ovarian mesenchymal hyperplasia and hyperandrogenism characteristic of PCOS.

Rhabdomyolysis associated with hydroxymethylglutaryl-coenzyme A reductase inhibitors

BACKGROUND

The recent withdrawal of cerivastatin by the manufacturer has led to an interest in hydroxymethylglutaryl-coenzyme A (HMG-CoA) inhibitors and the incidence of myopathy. We review the epidemiology, pharmacology, and presumed mechanisms of statin-induced myopathy, with a particular focus on cerivastatin.

METHODS

A MEDLINE search of English-language articles published between 1985 and 2003 was performed. Key words included HMG-CoA inhibitors, statins, myopathy, myotoxicity, rhabdomyolysis, adverse events, drug interactions, and cerivastatin.

RESULTS

The initial trials, which assessed the efficacy of first-generation HMG-CoA inhibitors, did not show a clinically significant increase in the incidence of myopathy. However, on the basis of Food and Drug Administration post-marketing surveys, the rate of cerivastatin-induced rhabdomyolysis appeared to be 10-fold greater than that of the other statins, despite safe pre-clinical profiles. However, no clinical trials have been performed directly comparing the rates of myotoxicity of all commercially available statins. The mechanism of statin-induced myopathy remains unclear. The prevailing theory is that lipophilic statins lead to depletion of intermediates normally formed after cholesterol synthesis within myocytes. Risk factors for the development of myopathy include drug interactions (especially with fibrates) and the coexistence of conditions known to predispose patients to rhabdomyolysis.

CONCLUSION

The cerivastatin experience emphasizes the need for large safety trials before drug approval and for vigilant post-marketing surveillance. Further research and sound clinical judgment may lead to the identification of high-risk individuals in whom statins should be avoided.

Analytical methods for the quantitative determination of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in biological samples

Published analytical methods for the quantitative determinations of presently available five 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ("statins"), lovastatin, simvastatin, pravastatin, fluvastatin and atorvastatin, are reviewed for therapeutic drug monitoring purpose in patients. Almost all assay reviewed are based on high-performance liquid chromatography or gas chromatography. Some purification steps (liquid-liquid extraction, solid-phase extraction, etc.) have been used before they are submitted to separation by chromatographic procedures and they are detected by various detection methods like UV, fluorescence and mass spectrometry. This review shows that most method may be used quantitative determination of statins in plasma and they are suitable for therapeutic drug monitoring purpose of these drugs.

Lovastatin and beyond: the history of the HMG-CoA reductase inhibitors

In the 1950s and 1960s, it became apparent that elevated concentrations of plasma cholesterol were a major risk factor for the development of coronary heart disease, which led to the search for drugs that could reduce plasma cholesterol. One possibility was to reduce cholesterol biosynthesis, and the rate-limiting enzyme in the cholesterol biosynthetic pathway, 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, was a natural target. Here, I describe the discovery and development of lovastatin--the first approved inhibitor of HMG-CoA reductase--and the clinical trials that have provided the evidence for the ability of drugs in this class to reduce the morbidity and mortality associated with cardiovascular disease.

The discovery and development of atorvastatin, a potent novel hypolipidemic agent

The search for potent and efficacious inhibitors of the enzyme HMG-CoA reductase (HMGRI) was the focus of considerable research in the 1980s. Building on the discovery of the fungal metabolite-derived inhibitors, mevastatin, lovastatin, pravastatin and simvastatin, a number of totally synthetic inhibitors were discovered and developed. This manuscript describes the discovery and development of one of those synthetic inhibitors, atovastatin calcium, currently marketed in the United States as LIPITOR. This inhibitor was designed based in part on molecular modeling comparisons of the structures of the fungal metabolites and other synthetically derived inhibitors. In addition to development of the structure-activity relationships which led to atorvastatin calcium, another critical aspect of the development of this area was the parallel improvement in the chemistry required to prepare compounds of the increased synthetic complexity needed to potently inhibit this enzyme. Ultimately, the development of several chiral syntheses of enantiomerically pure atorvastatin calcium was accomplished through a collaborative effort between discovery and development. The impact of the progress of the required chemistry as well as external factors on internal decision-making with regards to the development of atorvastatin calcium will be discussed.

A new and efficient chemoenzymatic route to both enantiomers of 4-hydroxycyclohex-2-en-1-one

[reaction: see text] A chemoenzymatic synthesis of both enantiomers of the pharmacologically interesting 4-hydroxycyclohex-2-en-1-one in three steps starting from 3-methoxycyclohex-2-en-1-one is described. Manganese(III) acetate-mediated acetoxylation followed by enzyme-mediated hydrolysis of alpha-acetoxy enone affords acetoxy enone 3 and hydroxy enone 4 with high enantiomeric excesses and in good yields. The reduction of the acetoxy and hydroxy enones furnished both enantiomers of 4-hydroxycyclohex-2-en-1-one in high enantiomeric excess.

What is the optimal medical management of ischemic heart failure?

Ischemic heart disease is an important and common contributor to the development of heart failure. Theoretically, all patients with heart failure may benefit from treatment designed to retard progressive ventricular dysfunction and arrhythmias. Patients with ischemic heart disease may also theoretically benefit from the relief of ischemia, the prevention of coronary occlusion, and revascularization. However, there is little evidence to show that the presence or absence of coronary disease modifies the benefits of effective treatments such as angiotensin-converting enzyme inhibitors and beta-blockers. Moreover, there is no evidence that treatment directed specifically at myocardial ischemia or coronary disease alters outcome in patients with heart failure. Treatments aimed at relieving painless myocardial ischemia have not been shown to alter prognosis. Lipid-lowering therapy is theoretically attractive for patients with heart failure and coronary disease; however, theoretical concerns also exist about the safety of such agents, and patients with heart failure have been excluded from large outcome studies very effectively. Some agents, such as aspirin, designed to reduce the risk of coronary occlusion seem ineffective or harmful in patients with heart failure, although warfarin may be safe and possibly effective. There is no evidence yet that revascularization improves prognosis in patients with heart failure, even in patients who are shown to have extensive myocardial hibernation. On current evidence, revascularization should be reserved for the relief of angina. Large-scale, randomized controlled trials are currently underway that are investigating the role of specific treatments targeted at coronary syndromes. The Carvedilol Hibernation Reversible Ischemia Trial: Marker of Success study is investigating the effects of carvedilol in a large cohort of patients with and without hibernating myocardium. The Warfarin and Antiplatelet Therapy in Chronic Heart Failure study is comparing the efficacy of aspirin, clopidogrel, and warfarin. The Heart Revascularization Trial-United Kingdom study is assessing the effect of revascularization on mortality in patients with heart failure and myocardial hibernation. Smaller scale studies are assessing the safety and efficacy of statin therapy in patients with heart failure. Only once the outcomes to these and other planned trials are known can the medical community know how best to treat their patients.

What is the optimal medical management of ischaemic heart failure?

Ischaemic heart disease is probably the most important cause of heart failure. All patients with heart failure may benefit from treatment designed to retard progressive ventricular dysfunction and arrhythmias. Patients with heart failure due to ischaemic heart disease may also, theoretically, benefit from treatments designed to relieve ischaemia and prevent coronary occlusion and from revascularisation. However, there is little evidence to show that effective treatments, such as angiotensin converting enzyme (ACE) inhibitors and beta-blockers, exert different effects in patients with heart failure with or without coronary disease. Moreover, there is no evidence that treatment directed specifically at myocardial ischaemia, whether or not symptomatic, or coronary disease alters outcome in patients with heart failure. Some agents, such as aspirin, designed to reduce the risk of coronary occlusion appear ineffective or harmful in patients with heart failure. There is no evidence, yet, that revascularisation improves prognosis in patients with heart failure, even in patients who are demonstrated to have extensive myocardial hibernation. On current evidence, revascularisation should be reserved for the relief of angina. Large-scale, randomised controlled trials are currently underway investigating the role of specific treatments targeted at coronary syndromes in patients who have heart failure. The CHRISTMAS study is investigating the effects of carvedilol in a large cohort of patients with and without hibernating myocardium. The WATCH study is comparing the efficacy of aspirin, clopidogrel and warfarin. The HEART-UK study is assessing the effect of revascularisation on mortality in patients with heart failure and myocardial hibernation. Smaller scale studies are currently assessing the safety and efficacy of statin therapy in patients with heart failure. Only when the results of these and other studies are known will it be possible to come to firm conclusions about whether patients with heart failure and coronary disease should be treated differently from other patients with heart failure due to left ventricular systolic dysfunction.

Constituents of red yeast rice, a traditional Chinese food and medicine

Detailed analyses were undertaken of the natural constituents of red yeast rice, a traditional Chinese medicine and food known for centuries to improve blood circulation. Preparation of red yeast rice following ancient methods by fermenting the fungal strain Monascus purpureus Went on moist and sterile rice indicated the presence of a group of metabolites belonging to the monacolin family of polyketides, together with fatty acids, and trace elements. The presence of these compounds may explain in part the cholesterol-lowering ability associated with this traditional Chinese food.

Heart failure due to ischaemic heart disease: epidemiology, pathophysiology and progression

Ischaemic heart disease is the most common underlying cause of heart failure in industrialised countries. Its manifestations are protean with myocardial infarction being only one important facet. The prognosis of patients with heart failure due to ischaemic heart disease also appears to be worse than that associated with many other aetiologies. The presence of ischaemic heart disease may influence both the efficacy and choice of treatment. Agents such as digoxin and amlodipine appear less effective in patients with ischaemic heart disease while ACE inhibitors and beta-blockers appear as or more effective in patients with ischaemic heart disease. Many have expressed an opinion about how coronary disease should be managed in the patient with heart failure supported by little or no evidence. There are major theoretical and practical concerns about the use of anti-coagulant, anti-platelet and statin therapy in patients with heart failure as well as major theoretical benefits. Only randomised controlled trials will resolve these issues. The same may be said of revascularisation. Fortunately trials addressing all these areas are under way. This should put the management of coronary disease in patients with heart failure on a firm evidence-based footing.

Metabolic modes of action of the statins in the hyperlipoproteinemias

Conflicting results have been published during the past few years regarding the physiologic modes of action of the hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors, generally referred to as statins, using standard doses. Three mechanisms have been described: increased LDL catabolic rate, increased removal of LDL precursors resulting in decreased LDL production and decreased VLDL production. The physiologic effects of statins seem to depend on the underlying pathology of the disorders under therapy. More recent data using either the more potent atorvastatin or larger doses of previously available statins (e.g. simvastatin 80-160 mg/day), suggest that both the potency of the statins and the underlying pathopHysiology are important in determining the predominant physiologic responses of patients. To understand physiologic responses more completely, drug-dose-physiologic response curves of apo B kinetics in various groups of patients are needed. Simultaneous studies of apo B, triglycerides and cholesterol metabolism are also needed and are currently feasible.

Clinical efficacy and safety of cerivastatin in the treatment of heterozygous familial hypercholesterolemia

Patients with heterozygous familial hypercholesterolemia are at especially high risk of premature coronary artery disease and usually require aggressive long-term lipid-lowering drug therapy to decrease plasma low-density lipoprotein (LDL) cholesterol concentrations to normal levels. In the present study, the lipid-lowering effects of cerivastatin in combination with cholestyramine and probucol were investigated in 20 patients with heterozygous familial hypercholesterolemia over a 20-week treatment period. After an initial 4-week treatment with once-daily 0.2 mg cerivastatin, serum total cholesterol and LDL cholesterol levels had decreased by a significant 22% and 25%, respectively (p <0.01). The addition of 8 g/day cholestyramine or 1 g/day probucol to ongoing cerivastatin therapy produced further significant reductions in total cholesterol of 16% and 16%, respectively, and in LDL cholesterol of 22% and 15%, respectively (p <0.01), over the 12-week combination therapy period. The potent lipid-lowering effects of combined treatment were accompanied by excellent toleration of study drugs. Only 2 patients experienced gastrointestinal side effects associated with cholestyramine therapy. There was no evidence of any abnormalities in creatine phosphokinase in either treatment group and only 2 patients exhibited minor increases in hepatic transaminases. This study has shown that cerivastatin can be safely combined with either cholesytramine or probucol to provide a safe and highly effective hypolipidemic treatment regimen for patients with heterozygous familial hypercholesterolemia.

Determination of pravastatin in human plasma by high-performance liquid chromatography with ultraviolet detection

A sensitive high-performance liquid chromatographic (HPLC) method for the quantitation of the HMG-CoA reductase inhibitor pravastatin in human plasma is described. Sample preparation based on reversed-phase solid-phase extraction using triamcinolone acetonide as internal standard (I.S.). The compounds were separated on C18 reversed-phase analytical column and then determined by ultraviolet detection. The recovery of pravastatin from plasma was 69.2+/-6.7% (mean+/-S.D.). The limit of detection for pravastatin in aqueous solution was 0.4 ng, the limit of quantitation in plasma was 2 ng/ml. In a preliminary pharmacokinetic study with two healthy volunteers the t1/2 of pravastatin in plasma was found to be 0.8 and 2.3 h.

Peripheral neuropathy associated with simvastatin

Four patients are described who developed sensorimotor neuropathy while being treated with simvastatin and had complete or partial resolution of clinical abnormalities after withdrawal of treatment. In one case onset was within days of commencing treatment, but in two cases symptoms did not develop for two years. The electrophysiological and pathological features of the neuropathy were those of axonal degeneration. Clinical evidence of proximal and distal weakness and muscle fasciculations and persistent abnormalities of sensory conduction after recovery suggest the possibility of toxic damage to anterior horn cells and dorsal root ganglia. Thirty eight other cases with symptoms suggestive of peripheral neuropathy have been reported to the Australian Adverse Drug Reactions Advisory Committee, 22 of whom recovered after cessation of treatment; in five cases there was recurrence after re-exposure to the drug. Simvastatin should be considered among the causes of peripheral neuropathy, and the drug should be withdrawn if patients receiving it develop muscle weakness or sensory disturbances.

Exogenous CoQ10 preserves plasma ubiquinone levels in patients treated with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors

Ubiquinone is a carrier of the mitochondrial respiratory chain which regulates oxidative phosphorylation: it also acts as a membrane stabilizer preventing lipid peroxidation. In man the quinone ring originates from tyrosine, while the formation of the polyisoprenoid lateral chain starts from acetyl CoA and proceeds through mevalonate and isopentenylpyrophosphate; this biosynthetic pathway is the same as the cholesterol one. We therefore performed this study to evaluate whether statins (hypocholesterolemic drugs that inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase) modify blood levels of ubiquinone. Thirty unrelated outpatients with primary hypercholesterolemia (IIa phenotype) were treated with 20 mg of simvastatin for a 3-month period (group S) or with 20 mg of simvastatin plus 100 mg CoQ10 (group US). The following parameters were evaluated at time 0, and at 45 and 90 days: total plasma cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, triglycerides, Apo A1, Apo B and CoQ10 in plasma and in platelets. In the S group, there was a marked decrease in total cholesterol low-density lipoprotein-cholesterol and in plasma CoQ10 levels from 1.08 mg/dl to 0.80 mg/dl. In contrast, in the US group we observed a significant increase of plasma CoQ10 (from 1.20 to 1.48 mg/dl) while the hypocholesterolemic effect was similar to that observed in the S group. Platelet CoQ10 also decreased in the S group (from 104 to 90 ng/mg) and increased in the US group (from 95 to 145 ng/mg).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute hepatitis induced by HMG-CoA reductase inhibitor, lovastatin

The HMG-CoA reductase inhibitor, lovastatin, is known to induce asymptomatic liver dysfunction in a few patients. We report the case of an adult who suffered from clinical hepatitis three months after the onset of lovastatin administration. Manifestations included asthenia, jaundice, and increased aminotransferase and alkaline phosphatase activities. Histologic examination showed centrilobular necrosis, centrilobular cholestasis, and infiltrates with mononuclear and polymorphonuclear cells, including eosinophils. Withdrawal of lovastatin was followed by complete normalization of liver tests within two months.

Drug and alternative therapies for hyperlipidemia

The recent guidelines for detection and treatment of hypercholesterolemia together with specific therapeutic goals have stimulated interest in, and use of, lipid lowering agents. The last decade has seen an explosive growth in the drug discovery area which is now translating into clinical trials with many new lipid lowering agents. In addition, clinical trials assessing clinical outcomes and cost effectiveness are resulting in a changing approach to how current lipid lowering drugs are used, especially in terms of dosing and combination therapies. At present only four classes of lipid altering agents remain in wide use; bile acid binding resins, niacin, fibrates and HMG CoA reductase inhibitors. Although only a decade has passed since the first HMG CoA reductase inhibitor, lovastatin, entered clinical trials this group of compounds are not only the most widely used lipid lowering agents, but more than six such agents have been or are currently being developed. In addition to pharmacological therapies, there have been significant advances in the non-pharmacological treatment of hypercholesterolemia, the most important being LDL-receptor gene replacement and selective LDL-apheresis.

Influences of lovastatin administration on the respiratory burst of leukocytes and the phosphorylation potential of mitochondria in guinea pigs

Lovastatin, a cholesterol-lowering drug, decreased plasma cholesterol and cardiac tissue coenzyme Q10 levels in guinea pigs given 20 mg per kg body weight twice a day. Plasma cholesterol levels were reduced 40% in animals 2 to 4 months of age and 61% in animals 2 years of age. Coenzyme Q10 values in cardiac muscle and cardiac mitochondria of the treated, older group were decreased 31% and 37%, respectively. A significant decrease was not observed in coenzyme Q10 levels of the younger animal group. The potential to phosphorylate ADP to ATP driven by pyruvate-malate and succinate oxidation was decreased 43% and 45%, respectively, for cardiac mitochondria from the treated, 2-year-old animals. A decrease in phosphorylation potential was not observed for the younger group. The respiratory burst of leukocytes isolated from the intraperitoneal cavities of the treated, older animals was decreased 67%, while leukocytes isolated directly from their blood was decreased 76% (Diebold, B., Bhagavan, N. and Guillory, R. (1991) FASEB J. 5, A1203). In contrast to the intact leukocytes, the superoxide production of the cell-free systems prepared from leukocytes isolated from treated and untreated animals did not differ significantly. These observations suggest that in vivo lovastatin may not directly affect the leukocyte superoxide generating system, but may influence it indirectly possibly by modifying the lipid content of the membrane.

Plasma coenzyme Q (ubiquinone) concentrations in patients treated with simvastatin

Plasma coenzyme Q (CoQ) was measured in 20 hyperlipidaemic patients treated with diet and simvastatin (an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase); 22 hyperlipidaemic patients treated with diet with alone; and 20 normal controls. Patients treated with simvastatin had a significantly lower plasma CoQ and CoQ: cholesterol ratio than either patients receiving diet alone or normal controls. Use of simvastatin was inversely and independently correlated with both CoQ (p < 0.0001) and CoQ: cholesterol ratio (p < 0.01). There was a significant inverse association between CoQ and dose of simvastatin (p < 0.001). It is concluded that simvastatin may lower the plasma CoQ concentration and this may be greater than the reduction in cholesterol. The possible adverse effect of simvastatin on the metabolism of CoQ may be clinically important and requires further study.

Treatment of hyperlipidemia in the nephrotic syndrome: the effects of pravastatin therapy

The hyperlipidemia of the nephrotic syndrome is characterized by an elevation of total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC), with a normal or low high-density lipoprotein cholesterol (HDLC), and an increase in triglycerides (TGs) later in the course of the disease. If sustained, this lipid profile probably places these patients at increased risk for cardiovascular disease. Despite extensive trials of diet and drug therapy in patients with primary hyperlipidemias, few such trials exist in patients with the nephrotic syndrome. We conducted a randomized, prospective, double-blind, placebo-controlled trial to investigate the efficacy and safety of pravastatin, the newest cholesterol synthesis inhibitor, in the treatment of the hyperlipidemia of the nephrotic syndrome. After dietary modification was implemented, 13 patients received pravastatin and eight received placebo. All patients were maintained on a low-fat, low-cholesterol diet for the duration of the trial (24 weeks). The dose of pravastatin was increased from the initial 20 mg/d to 40 mg/d at week 10 or 18 if TC remained elevated (> 50th percentile). A bile acid sequestrant was added at week 18 if TC remained elevated and if the patient was already receiving the maximal pravastatin dosage. Dietary modification did not significantly change the lipid profile. Pravastatin (20 mg/d) reduced TC by 22% from a baseline of 301 +/- 28 mg/dL (P < 0.05) and LDLC by 28% from a baseline of 222 +/- 28 mg/dL (P < 0.05). When used at 40 mg/d (in six patients) no further change in the lipid profile was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence of plasma CoQ10-lowering effect by HMG-CoA reductase inhibitors: a double-blind, placebo-controlled study

Inhibitors of HMG-CoA reductase are new safe and effective cholesterol-lowering agents. Elevation of alanine-amino transferase (ALT) and aspartate-amino transferase (AST) has been described in a few cases and a myopathy with elevation of creatinine kinase (CK) has been reported rarely. The inhibition of HMG-CoA reductase affects also the biosynthesis of ubiquinone (CoQ10). We studied two groups of five healthy volunteers treated with 20 mg/day of pravastatin (Squibb, Italy) or simvastatin (MSD) for a month. Then we treated 30 hypercholesterolemic patients in a double-blind controlled study with pravastatin, simvastatin (20 mg/day), or placebo for 3 months. At the beginning, and 3 months thereafter we measured plasma total cholesterol, CoQ10, ALT, AST, CK, and other parameters (urea, creatinine, uric acid, total bilirubin, gamma GT, total protein). Significant changes in the healthy volunteer group were detected for total cholesterol and CoQ10 levels, which underwent about a 40% reduction after the treatment. The same extent of reduction, compared with placebo was measured in hypercholesterolemic patients treated with pravastatin or simvastatin. Our data show that the treatment with HMG-CoA reductase inhibitors lowers both total cholesterol and CoQ10 plasma levels in normal volunteers and in hypercholesterolemic patients. CoQ10 is essential for the production of energy and also has antioxidative properties. A diminution of CoQ10 availability may be the cause of membrane alteration with consequent cellular damage.

Effects of mevinolin treatment on tissue dolichol and ubiquinone levels in the rat

Rats were treated with mevinolin by intraperitoneal injection (15 days) or dietary administration (30 days). The cholesterol, dolichol, dolichyl phosphate and ubiquinone contents of the liver, brain, heart, muscle and blood were then investigated. The cholesterol contents of these organs did not change significantly, with the exception of muscle. Intraperitoneal administration of the drug increases the amount of dolichol in liver, muscle and blood and decreases the dolichyl-P amount in muscle. The same treatment increases the level of ubiquinone in muscle and blood and decreases this value in liver and heart. Oral administration decreases dolichol, dolichyl-P and ubiquinone levels in heart and muscle, while in liver the dolichol level is elevated and ubiquinone level lowered. In brain the amount of dolichyl-P is increased. Intraperitoneal injection of mevinolin also modifies the liver dolichol and dolichyl-P isoprenoid pattern, with an increase in shorter chain polyisoprenes. The levels of dolichol and ubiquinone in the blood do not follow the changes observed in other tissues. Incorporation of [3H]acetate into cholesterol by liver slices prepared from mevinolin-treated rats exhibited an increase, whereas in brain no change was seen. Labeling of dolichol and ubiquinone was increased in both liver and brain, but incorporation into dolichyl phosphate remained relatively stable. The results indicate that mevinolin affects not only HMG-CoA reductase but, to some extent, also affects certain of the peripheral enzymes, resulting in considerable effects on the various mevalonate pathway lipids.

Lathosterol and other noncholesterol sterols during treatment of hypercholesterolemia with lovastatin alone and with cholestyramine or guar gum

Sixty-two patients aged 19-64 years with primary hypercholesterolemia (mean level of total cholesterol, 10.8 mmol/l) were treated with 80 mg/day lovastatin (L) alone for 18 weeks and, after randomization to either L + 20 g/day guar gum (L + GG) or L + 16 g/day cholestyramine (L + C) treatments, for an additional 18 weeks. The total cholesterol level declined from baseline by 34% during L and by 44% and 48% during L + GG and L + C, respectively. In terms of micromoles per millimole of cholesterol, serum levels of the cholesterol synthesis precursors cholestenol, desmosterol, and lathosterol were decreased and those of the plant sterols campesterol and sitosterol were increased by treatment with L. The serum contents of cholesterol precursors were increased markedly after the combination of either GG or C with L, but the increase was greater after the addition of C (e.g., the lathosterol to cholesterol ratio was 51% versus 212% for L + GG and L + C, respectively; p less than 0.001). Thus, a higher rate of removal of bile acids by C than by GG reduced more effectively the low density lipoprotein cholesterol level but simultaneously stimulated cholesterol synthesis compensatorily to a higher level even under concurrent treatment with L. The serum sitosterol to cholesterol ratio declined by 13% during L + GG but increased by 49% during L + C compared with the value under L alone, suggesting different effects of GG and C on the metabolism of plant sterols.

Antioxidant activity of ubiquinone-3 in human low density lipoprotein

The ability of ubiquinone-3, a short chain ubiquinone homologue, to prevent Cu2+ induced oxidation of human low density lipoprotein was investigated. The results are as follows: in the presence of ubiquinone-3 the extent of peroxidation, as determined by the formation of thiobarbituric acid reactive substances, was only one third of that found in its absence; the quinone can also prevent the fragmentation of apolipoprotein B-100 and the increase of the net negative surface charge of the particle.

Effects of exercise and lovastatin on serum creatine kinase activity

Vigorous physical activity and lovastatin (Mevacor) a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, have both been independently associated with elevated creatine kinase (CK) levels. To determine the effect of lovastatin plus exercise on serum CK activity, we measured CK levels before and after maximal treadmill exercise in 14 men (51.6 +/- 17.3 years, mean +/- SD) and 6 women (48.5 +/- 7.4 years) before and after 4 weeks of lovastatin treatment (20 mg/d). Blood samples were obtained before, immediately after, and 24 hours after exercise. Individual subjects were exercised for the same duration on each test. Preexercise CK levels and the average CK response to treadmill exercise did not differ before and after lovastatin treatment. In two men taking lovastatin, however, CK levels increased by 183% and 242% 24 hours after exercise during lovastatin administration. We conclude that low-dose lovastatin treatment plus exercise does not affect average CK activity but that this combination may markedly increase CK levels in certain individuals.

Effect of simvastatin on receptor mediated metabolism of low density lipoprotein in guinea pigs

This study examined the effects of simvastatin, an inhibitor of HMG-CoA reductase, on the metabolism of labelled human low density lipoprotein (LDL) in animal models. Administration of 10 mg/kg per day simvastatin for 2 weeks reduced the levels of total cholesterol, LDL-cholesterol and triglycerides by 5.7 mg/dl (16%), 8.8 mg/dl (36%) and 4.9 mg/dl (13%), respectively in guinea pigs. High density lipoprotein-cholesterol levels rose 0.8 mg/dl (29%) by simvastatin treatment. Measurements of turnover of LDL were determined between simvastatin-treated guinea pigs and untreated guinea pigs using intravenous injection of 131I-labelled LDL and 125I-labelled galactose-treated LDL to quantify the LDL receptor pathway. Simvastatin significantly increased the fractional catabolic rate (FCR) of the LDL receptor-dependent pathway. In contrast, the FCR of the LDL receptor-independent pathway was not altered by simvastatin therapy. The FCR for LDL isolated from simvastatin-treated subjects compared to that from control subjects was very similar in both control and simvastatin-fed guinea pigs. These findings suggest that simvastatin mainly reduced serum cholesterol levels by accelerated FCR of LDL receptor mediated pathway.

Long-term effects of simvastatin in familial dysbetalipoproteinaemia

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.

Pravastatin sodium, a new HMG-CoA reductase inhibitor

The rate-limiting step in cholesterol biosynthesis is controlled by the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. Inhibitors of this enzyme lower serum cholesterol very efficiently by increasing cellular uptake of cholesterol-rich, low-density lipoproteins. Pravastatin, a derivative of mevastatin and in the same class as lovastatin, lowers total cholesterol concentrations by 20-30 percent in patients with hypercholesterolemia. In patients who also have hypertriglyceridemia, serum triglyceride levels are decreased. Detailed pharmacokinetic data and long-term adverse-effect experience with pravastatin are extremely limited. The issue of tissue-selectivity for pravastatin has given rise to the marketing terminology "second-generation" HMG-CoA reductase inhibitor, but any clinical advantage of pravastatin over other HMG-CoA reductase inhibitors remains to be demonstrated.

Simvastatin: a review of its pharmacology and clinical use

Simvastatin, a chemical derivative of lovastatin, is an antihyperlipidemic medication that inhibits hydroxymethylglutaryl coenzyme A reductase. Animal and clinical data suggest simvastatin is twice as potent as lovastatin. It lowers serum cholesterol by inhibiting hepatic synthesis of cholesterol and, more importantly, by increasing the number of low-density lipoprotein (LDL) receptors present on hepatic cellular membranes. Simvastatin, when used at doses of 40 mg/d in patients with heterozygous familial hypercholesterolemia, significantly reduces total cholesterol (greater than 30 percent) and LDL cholesterol (35-45 percent) and tends to reduce triglycerides and raise high-density lipoprotein (HDL) cholesterol. The agent is also effective in patients with polygenic hypercholesterolemia, familial dysbetalipoproteinemia, and nephrotic syndrome. Addition of cholestyramine to simvastatin enhances the LDL cholesterol-lowering effect to approximately 55 percent. Common clinical adverse effects reported with simvastatin use include headaches and gastrointestinal complaints. Transient elevations in serum transaminases and creatine phosphokinase have also been seen. Based on data currently available, the drug's clinical activity and adverse-effect profile are similar to those of lovastatin. Therefore, there is no need for formularies to contain both medications. To choose between the two, one needs to consider the incidence of adverse effects and the daily cost of each product when used at equally effective doses. That information is now now available and, until it is, a clear recommendation cannot be made. Simvastatin, presently marketed in several countries, is investigational in the U.S. but is expected to be available soon.

Hypolipidemic effect and mechanism of ketoconazole without and with cholestyramine in familial hypercholesterolemia

The hypocholesterolemic and metabolic effects of ketoconazole (400 mg/d) alone (inhibits cholesterol synthesis at 14 alpha-demethylation of lanosterol) and in combination with cholestyramine (12 g/d), were studied in nine women with xanthomatous familial hypercholesterolemia (FH). In addition to serum lipoprotein levels, cholesterol precursors, fecal steroids, and cholesterol absorption were measured before and during the drug treatments. Serum total and low-density lipoprotein (LDL)-cholesterol were reduced by 19% and 22% with ketoconazole; the respective changes were 16% and 21% for cholestyramine, and 31% and 41% for the combined ketoconazole and cholestyramine treatment. Serum triglycerides, very-low-density lipoprotein (VLDL)-and high-density lipoprotein (HDL)-cholesterol levels were unchanged. Accumulation of cholesterol precursors in serum suggested that ketoconazole inhibited cholesterol synthesis at delta 8-sterol levels. Serum and fecal lanosterols were increased up to 20-fold and were interrelated. Their maximal serum level was 1.3 mg/DL and the lanosterol contents were negatively related to the serum cholesterol levels. The intestinal absorption and total intestinal fluxes of cholesterol were reduced by 27% and 29%. Cholesterol and bile acid synthesis were decreased by ketoconazole only when combined with cholestyramine. The synthesis of chenodeoxycholic acid was deeply hindered by ketoconazole. Thus, ketoconazole efficiently lowers serum total and LDL-cholesterol levels in FH patients, probably by inhibiting cholesterol synthesis and absorption. Effective biliary and fecal outputs of cholesterol precursors prevent their excessive increase in serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in various forms of dyslipidemia

The inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase are highly effective in treating severe elevations of serum cholesterol, and are being widely used for this purpose. In our laboratory, these drugs have been used for the treatment of other forms of dyslipidemia including primary moderate hypercholesterolemia, primary mixed hyperlipidemia, diabetic dyslipidemia, hyperlipidemia of the nephrotic syndrome, and primary hypoalphalipoproteinemia. In these conditions, the HMG CoA reductase inhibitors proved effective in substantially decreasing levels of both low-density lipoproteins and very low density lipoproteins, as well as apolipoprotein B. In some patients, they may even increase levels of high-density lipoproteins. The primary mode of action of HMG CoA reductase inhibitors appears to be to increase the synthesis of hepatic receptors for lipoproteins containing apolipoprotein B, although a reduction in synthesis of these lipoproteins has not been ruled out with certainty. Regardless of mechanisms, drugs of this type appear to have the potential for effective therapy of various forms of dyslipidemia beyond primary severe hypercholesterolemia.