Pravastatin. A reappraisal of its pharmacological properties and clinical effectiveness in the management of coronary heart disease

Effect of Pravastatin on Kidney Function in Patients with Dyslipidemia and Type 2 Diabetes Mellitus: A Multicenter Prospective Observational Study

INTRODUCTION

Several studies have reported that pravastatin can mitigate the progression of kidney disease, but limited evidence exists regarding its effects on kidney function in Asian patients. This multicenter prospective observational study aimed to assess the effect of pravastatin on kidney function in Korean patients with dyslipidemia and type 2 diabetes mellitus (T2DM) in clinical practice.

METHODS

This 48-week prospective multicenter study included 2604 of 2997 eligible patients with dyslipidemia and T2DM who had available estimated glomerular filtration rate (eGFR) measurements. The primary endpoint was eGFR percent change at week 24 from baseline. We also assessed secondary endpoints, which included percent changes in eGFR at weeks 12 and 48 from baseline, as well as changes in eGFR, metabolic profiles (lipid and glycemic levels) at 12, 24, and 48 weeks from baseline, and safety.

RESULTS

We noted a significant improvement in eGFR, with mean percent changes of 2.5%, 2.5%, and 3.0% at 12, 24, and 48 weeks, respectively (all adjusted p < 0.05). The eGFR percent changes significantly increased in subgroups with baseline eGFR 30-90 mL/min/1.73 m2, glycated hemoglobin (HbA1c) ≥ 7 at baseline, no hypertension history, T2DM duration > 5 years, or previous statin therapy. Lipid profiles were improved and remained stable throughout the study, and interestingly, fasting glucose and HbA1c were improved at 24 weeks.

CONCLUSION

Our findings suggest that pravastatin may have potential benefits for improving eGFR in Korean patients with dyslipidemia and T2DM. This could make it a preferable treatment option for patients with reduced kidney function.

TRIAL REGISTRATION NUMBER

NCT05107063 submitted October 27, 2021.

Pravastatin and fenofibrate in combination (Pravafenix(®)) for the treatment of high-risk patients with mixed hyperlipidemia

Pravafenix(®) is a fixed-dose combination of pravastatin 40 mg and fenofibrate 160 mg. The rationale for the use of Pravafenix is based on the increased residual cardiovascular risk observed for high-risk patients with either increased triglycerides or low HDL cholesterol levels despite statin monotherapy. This article reviews the current available information on the pharmacology, clinical efficacy and safety of Pravafenix. Pravafenix is recommended to be taken with food in the evening. In clinical trials, Pravafenix consistently produces complementary benefits on the overall atherogenic lipid profile of high-risk patients with mixed hyperlipidemia not controlled by either pravastatin 40 mg or simvastatin 20 mg. Within the limitations of the database, Pravafenix seems to be well tolerated up to 64 weeks, with an overall tolerability and safety profile consistent with findings generally observed with fenofibrate treatment. In particular, no myopathy or rhabdomyolysis has been reported. The actual European indication is restricted to high-risk patients with mixed hyperlipidemia whose LDL cholesterol levels are adequately controlled on pravastatin 40 mg monotherapy. Whether Pravafenix confers additional cardiovascular benefits in high-risk patients treated with a statin remains to be determined.

Orange juice and its component, hesperidin, decrease the expression of multidrug resistance-associated protein 2 in rat small intestine and liver

We investigated the effects of orange juice (OJ) or hesperidin, a component of OJ, on the pharmacokinetics of pravastatin (PRV) and the expression of both protein and mRNA of multidrug resistance-associated protein 2 (Mrp2) in the rat small intestine and liver. Eight-week-old male Sprague-Dawley rats were used in this study. OJ or a 0.079% hesperidin suspension was administered orally for 2 days. Tap water was given as a control. A single dose of PRV at 100 mg/kg p.o. was administered after 2 days of OJ, hesperidin, or tap water ingestion. The AUC, C_max, and t_1/2 values of PRV were significantly increased in OJ group. Mrp2 protein and mRNA levels in the small intestine and liver, respectively, were significantly decreased after the ingestion of OJ. The same results were obtained with hesperidin. These results suggest that the changes in PRV pharmacokinetic parameters and the decrease in Mrp2 expression caused by OJ are due to hesperidin in the juice.

Chromatography–mass spectrometry methods for the quantitation of statins in biological samples

The 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors, more commonly known as 'statins', are a novel class of drugs widely used for the treatment of hypercholesterolaemia in patients with established cardiovascular disease as well as those at high risk of developing atherosclerosis. Published chromatographic-mass spectrometric methods for the quantification of presently available seven statins, atorvastatin, simvastatin, lovastatin, pravastatin, fluvastatin, rosuvastatin and pitavastatin are reviewed. High performance liquid chromatography (HPLC) in combination with tandem mass spectrometry (MS/MS) is the analytical technique of choice for the quantification of statins in biological samples. This review envisages that most of the methods used for quantification of statins are in plasma and they are suitable for therapeutic drug monitoring of these drugs.

Statins and myotoxicity: a therapeutic limitation

Hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors represent the most successful class of drugs for the treatment of hypercholesterolaemia and dyslipidaemia implicated in the pathogenesis of coronary heart disease and atherosclerosis. However, the popular profile of statins in terms of efficacy has been maligned by its adverse events. The myotoxicity, ranging from mild myopathy to serious rhabdomyolysis, associated with HMG-CoA reductase inhibitors, during treatment of hypercholesterolaemia is of paramount importance. Rhabdomyolysis is a rare but idiosyncratic muscle wasting disorder of different etiologies. Statin-associated rhabdomyolysis causes skeletal muscle injury by self-perpetuating events leading to fatal irreversible renal damage through a series of biochemical reactions. Preferential distribution and action of statins in liver could be the key to minimise myotoxicity concerns. Hepato-specific distribution of statins is governed by various factors such as physicochemical properties, pharmacokinetic properties and selective transporter-mediated uptake in liver rather in extrahepatic cells. The interactions of statins with concomitant drugs of different classes merit attention for their safety profile. Although pharmacokinetic as well as pharmacodynamic interactions have been implicated in pathophysiology of statin-induced muscle wasting, the underlying mechanism is not clearly understood. Besides, pharmacokinetic and phramcodynamic factors, statin-associated myotoxcity may also implicate pharmacogenomic factors. The pharmacogenomics characterised by CYP polymorphism and other genetic factors is responsible for inter-individual variations to efficacy and tolerability of statins. The pathophysiological mechanisms may include statin-induced differences in cholesterol:phospholipid ratio, isoprenoid levels, small GTP binding proteins and apoptosis. However, the present understanding of pathophysiological mechanisms, does not offer a reliable approach to address the same at preclinical level. Although statin-associated myotoxicity affects compliance, quality of life of patient and discontinuation rate, yet the low incidence of myotoxicty including rhabdomyolysis and less severity of commonly occurring myopathy and myalgia do not raise doubts about the clinical efficacy and tolerability of statins. Medical management of myotoxicity seems to be pivotal for the proper compliance of patients with statin treatment. The appropriate and judicious use of drugs would substantially reduce the likelihood of developing clinically important myopathy.

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.

Orange juice increased the bioavailability of pravastatin, 3-hydroxy-3-methylglutaryl CoA reductase inhibitor, in rats and healthy human subjects

Our objective was to investigate the effects of orange juice on the pharmacokinetics of pravastatin in rats and healthy volunteers. The pharmacokinetics of pravastatin (100 mg/kg p.o.) were assessed with water, orange juice, and carbohydrates (12.5 ml/kg over 30 min) and with acetic acid (0.1 M, pH 3.44). The pharmacokinetics of simvastatin (100 mg/kg p.o.) were assessed with water and orange juice. In addition, the pharmacokinetics (based on plasma levels) of pravastatin 80 mg/kg i.v. were assessed with water and orange juice (5 ml/kg) in rats. The pharmacokinetics of oral pravastatin (10 mg) were assessed when administered with water and orange juice (800 ml over 3 h) in a two-way crossover study in 14 healthy volunteers. Orange juice significantly increased the area under the curve (0-150 min) of pravastatin in rats. Orange juice had no effects on the pharmacokinetic parameters of intravenously administered pravastatin in rats. Carbohydrates and acetic acid with pH and concentration equivalent to those of orange juice also resulted in no statistically significant differences in pravastatin pharmacokinetic parameters in rats. Orange juice did not result in any significant differences in the pharmacokinetic parameters of simvastatin in rats. Orange juice significantly increased oatp1 and oatp2 mRNA and protein in the intestine of rats. Orange juice significantly increased the area under the curve (0-240 min) of pravastatin in healthy volunteers. In conclusion, orange juice increases the bioavailability of pravastatin administered orally. Oatp1 and oatp2 may be related to increases of pharmacokinetics of pravastatin by orange juice.

Cost-effectiveness analysis of cholesterol-lowering therapies in Spain

OBJECTIVE

To assess the cost efficacy of atorvastatin, simvastatin, lovastatin, fluvastatin, pravastatin, and colestyramine in the reduction of low-density lipoprotein-cholesterol (LDL-C) levels and the cost per patient to achieve the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) therapeutic objectives in Spain.

METHOD

The following treatments were evaluated: atorvastatin, simvastatin, and pravastatin 10-40 mg/day; lovastatin and fluvastatin 20-80 mg/day; and colestyramine 12-24 g/day. The cost effectiveness of these treatments was evaluated, in terms of cost per percentage of LDL-C reduction, by comparing annual treatment costs versus the efficacy of LDL-C reduction. Treatment costs included medication costs (2003 wholesale prices), control measures, and the treatment of adverse affects. The efficacy of HMG-CoA reductase inhibitors (statins) was obtained from a meta-analysis of results obtained from clinical trials published between 1993 and 2003 that met the following criteria: monotherapy; >16 weeks of treatment; randomized allocation of individuals to the intervention and comparator groups; dietary treatment for > or =3 months before administration of medication; and double-blind measurement of outcomes. Average and incremental cost-effectiveness ratios were calculated to assess the efficiency of cholesterol-lowering treatments.

RESULTS

Efficacy, in terms of percentage of LDL-C reduction, ranged from 10% for colestyramine 12 g/day to 49% for atorvastatin 40 mg/day. Total annual treatment costs ranged from euro 321 for fluvastatin 20 mg/day to euro 1151 for atorvastatin 40 mg/day. Cost-effectiveness ratios, in terms of cost per percentage of LDL-C reduced, were: euro 11-23 for atorvastatin; euro 12-21 for simvastatin; euro 14-22 for lovastatin; euro 15-24 for fluvastatin; euro 21-42 for pravastatin; and euro 35-46 for colestyramine. Atorvastatin 10 mg/day was the most cost-effective treatment, followed by simvastatin 10 mg/day, lovastatin 20 mg/day, and fluvastatin 20 mg/day. Atorvastatin was the most cost-effective treatment in the achievement of the NCEP ATP III LDL-C reduction objectives in patients with high (<100 mg/dL) and moderate (<130 mg/dL) risk of coronary heart disease (CHD), with a cost per patient of euro 747 and euro 405 per year, respectively. Fluvastatin was the most cost-effective treatment in the achievement of the NCEP ATPIII therapeutic objective in patients with low-risk of CHD (LDL-C <160 mg/dL), with a cost per patient of euro 321.

CONCLUSION

Atorvastatin 10 mg/day was the most cost-effective cholesterol-lowering drug, followed by simvastatin 10 mg/day, lovastatin 20 mg/day, and fluvastatin 20 mg/day. The preferred statin should be atorvastatin in patients with moderate-to-high CHD risk and fluvastatin in patients with low risk for CHD.

Determination of pravastatin in tablets by capillary electrophoresis

Pravastatin (PRA) is an inhibitor of HMG-CoA reductase enzyme, which is clinically used as a hypolipidemic agent to reduce cholesterol level. A capillary electrophoretic method for the determination of PRA in pharmaceutical tablet formulations is described. PRA and lansoprazole as an internal standard (IS) were well migrated in the background electrolyte of 10 mM borate buffer (pH 8.5) and 10% acetonitrile using a fused silica capillary. The separation was achieved by applying 27.5 kV, detecting at 200 nm and injecting the sample for 0.5 s and with an average migration time (tm) for PRA and IS of 4.7 and 3.9 min, respectively, at ambient temperature. The results were precise and repeatable for areas of the peaks and peak normalization ratio (PNPRA/PNIS). Linearity was found in the concentration range of 1.56-7.78 x 10(-5) M. Intra-day and Inter-day assays were performed and reliable results were obtained. Limit of detection and limit of quantitation were 8 x 10(-6) and 2.4 x 10(-5) M, respectively. The proposed method was successfully applied for the analysis of PRA in the pharmaceutical tablet formulation. The method proved simple, precise and fast since the analysis can be performed in less than 5 min.

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.

Lipid-lowering properties of TAK-475, a squalene synthase inhibitor, in vivo and in vitro

1. Squalene synthase is the enzyme that converts farnesyl pyrophosphate to squalene in the cholesterol biosynthesis pathway. We examined the lipid-lowering properties of 1-[[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-5-(2,3-dimethoxyphenyl)-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]acetyl]piperidine-4-acetic acid (TAK-475), a novel squalene synthase inhibitor. 2. TAK-475 inhibited hepatic cholesterol biosynthesis in rats (ED(50), 2.9 mg kg(-1)) and showed lipid-lowering effects in beagle dogs, marmosets, cynomolgus monkeys and Wistar fatty rats. 3. In marmosets, TAK-475 (30, 100 mg kg(-1), p.o., for 4 days) lowered both plasma non-high-density lipoprotein (HDL) cholesterol and triglyceride, but did not affect plasma HDL cholesterol. On the other hand, atorvastatin (10, 30 mg kg(-1), p.o., for 4 days) lowered the levels of all these lipids. A correlation between decrease in triglyceride and increase in HDL cholesterol was observed, and TAK-475 increased HDL cholesterol with a smaller decrease in triglyceride than did atorvastatin. 4. TAK-475 (60 mg kg(-1), p.o., for 15 days) suppressed the rate of triglyceride secretion from the liver in hypertriglyceridemic Wistar fatty rats, which show an enhanced triglyceride secretion rate from the liver compared with their lean littermates. 5. In HepG2 cells, TAK-475 and its pharmacologically active metabolite, T-91485, increased the binding of (125)I-low-density lipoprotein (LDL) to LDL receptors. 6. These results suggest that TAK-475 has clear hypolipidemic effects in animals via inhibition of hepatic triglyceride secretion and upregulation of LDL receptors, and that TAK-475 might increase HDL cholesterol by decreasing triglyceride. Thus, TAK-475 is expected to be useful for the treatment of dyslipidemia.

HMG-CoA reductase inhibitors as immunomodulators: potential use in transplant rejection

The benefit of HMG-CoA reductase inhibitors (statins) to the cardiovascular system is now well established and these drugs are being used extensively to treat hypercholesterolaemia clinically. However, as clinical outcomes become available it appears that statins are proving more beneficial than expected and thus it is being proposed that the actions of statins go beyond their ability to lower serum cholesterol levels. The report that statins can interact directly with lymphocyte function-associated antigen (LFA)-1 and prevent it engaging with the intracellular adhesion molecule (ICAM)-1 receptor on T cells is a novel mechanism of statin action and provides convincing evidence that these compounds can regulate biological systems other than by the cholesterol synthesis pathway. Immunosuppression to prevent organ transplant rejection is one application for which statins are currently being assessed. The clinical evidence is conflicting and does not convincingly reflect whether statins are beneficial as immunomodulators. However, in vivo studies investigating the cellular actions of statins have identified two mechanisms by which statins can potentially modulate an in vivo immune response. Firstly, statins regulate inducible class II major histocompatibility complex (MHC) expression on macrophages and endothelial cells. Secondly, statins can inhibit LFA-1 adhesion to ICAM-1 and thus regulate T cell activation. These findings suggest that statins have the potential to regulate an immune response in vivo and that more investigation is essential in order to explain the opposing clinical data.

Comparison of micronized fenofibrate and pravastatin in patients with primary hyperlipidemia

Micronized fenofibrate lowers total cholesterol and low-density lipoprotein cholesterol to a similar extent as statins but raises high-density lipoprotein cholesterol and lowers triglycerides to a greater extent. The comparative lipid-modifying efficacy of micronized fenofibrate and pravastatin has not been evaluated in dyslipidemic patients. This prospective, multicenter, randomized trial compared the efficacy of 3 months' treatment with micronized fenofibrate (200 mg once daily) or pravastatin (20 mg once daily) in hypercholesterolemic type IIa and mixed dyslipidemic type IIb patients. Two hundred sixty-five male and female patients (18-75 years) were recruited from 28 European centers, and 151 were analyzed. Micronized fenofibrate was at least as effective as pravastatin in reducing levels of low-density lipoprotein cholesterol and total cholesterol in primary dyslipidemia but was significantly more effective than pravastatin in raising high-density lipoprotein cholesterol (respectively, 13.2% vs. 5.6%; p = 0.0084) and lowering triglycerides (-38.7% vs. -11.8%; p = 0.0001). In type IIa dyslipidemia, micronized fenofibrate was as effective as pravastatin in raising high-density lipoprotein cholesterol (+8.6% vs. +8.0%) but was fivefold more effective in lowering triglycerides (-34.3% vs. -7.2%; p = 0.0001). In type IIb dyslipidemic patients with low baseline high-density lipoprotein cholesterol levels, micronized fenofibrate was 10-fold and nearly 3-fold superior to pravastatin in raising high-density lipoprotein cholesterol and lowering triglycerides, respectively. Micronized fenofibrate may be considered an effective first-line therapy for patients with primary hyperlipidemia, particularly those with type IIb mixed dyslipidemia or type 2 diabetes.

α-Heterosubstituted Aldehydes in Organic Synthesis. Enantioselective Approaches to New Analogues of Mevinic Acids

Various aldol approaches towards the asymmetric synthesis of the lactone moiety of HMG-CoA-reductase inhibitors are described. Auxiliary controlled as well as catalytic aldol reactions resulted only in modest to low selectivities, whereas 1,2-additions to readily available highly enantiomerically enriched α-heterosubstituted aldehydes yielded δ-hydroxy-β-ketoesters with a high degree of diastereocontrol and in good chemical yields. The novel mevinic acid analogues could then be obtained bysyn-reduction of the addition products.

Effects of HMG-CoA reductase inhibitors on skeletal muscle: are all statins the same?

The 3-hydroxy-3-methyl coenzyme A (HMG-CoA) reductase inhibitors or statins, specifically inhibit the enzyme HMG-CoA in the liver, thereby inhibiting the rate limiting step in cholesterol biosynthesis and so reducing plasma cholesterol levels. Numerous studies have consistently demonstrated that cholesterol lowering with statin therapy reduces morbidity and mortality from coronary heart disease, whilst recent evidence has demonstrated that benefits of statin therapy may also extend into stroke prevention. Since hypercholesterolaemia is a chronic condition, the long-term safety and tolerability of these agents is an important issue. Numerous large-scale clinical trials have consistently demonstrated a positive safety and tolerability profile for statins. Hepatic, renal and muscular systems are rarely affected during statin therapy, with adverse reactions involving skeletal muscle being the most common, ranging from mild myopathy to myositis and occasionally to rhabdomyolysis and death. Postmarketing data supports the positive safety and tolerability profile of statins, with an overall adverse event frequency of less than 0.5% and a myotoxicity event rate of less than 0.1%. The recent withdrawal of cerivastatin from the world market due to deaths from rhabdomyolysis has, however, focused attention on the risk of adverse events and in particular myotoxicity associated with statins. Indeed, initial clinical trial data supports postmarketing data, demonstrating a higher incidence of myotoxicity associated with cerivastatin, particularly when used in combination with fibrates. The potential mechanisms underlying statin-induced myotoxicity are complex with no clear consensus of opinion. Candidate mechanisms include intracellular depletion of essential metabolites and destabilisation of cell membranes, resulting in increased cytotoxicity. Cytochrome P450 3A4 is the main isoenzyme involved in statin metabolism. Reduced activity of this enzyme due to either reduced expression or inhibition by other drugs prescribed concomitantly such as cyclosporin or itraconazole may increase drug bioavailability and the risk of myotoxicity. Such factors may partly account for the interindividual variability in susceptibility to statin-induced myotoxicity, although other as of yet unclarified, genetic factors may also be involved. The risk of rhabdomyolysis is increased with combination fibrate-statin therapy, with initial evidence suggesting that gemfibrozil-statin combination may particularly increase the risk of myotoxicity, with pharmacodynamic as well as pharmacokinetic mechanisms being involved.

Simvastatin induces apoptosis of cultured rat cardiomyocytes

Considering the therapeutic effect of statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) and simvastatin in patients with coronary heart disease, our first hypothesis was that simvastatin should inhibit apoptosis (programmed cell death) in angiotensin II-treated cultured myocytes. But after realizing that simvastatin stimulates apoptosis, we changed our hypothesis and began to study its apoptotic effect in primary cultured rat cardiomyocytes. We found that simvastatin induced apoptosis in a dose-dependent manner (0.1 to 3 micromol/L), as evidenced by the appearance of increased DNA fragmentation in agarose gels and characteristic apoptotic patterns in nuclei labeled with Hoechst 33342, as well as increased activity of caspase 3. FACS analysis of simvastatin-treated cardiomyocytes showing annexin V binding and propidium iodide exclusion ruled out the possibility of necrosis. Increased intracellular enzymatic activity of creatine phosphokinase, aldolase, and lactic dehydrogenase, markers for normal cell function, could reflect the hypertrophic effect of simvastatin. The results indicate that simvastatin-induced apoptosis in cultured heart cells is concentration-dependent and additive to the apoptotic effect of angiotensin II.

Pharmacokinetic-pharmacodynamic drug interactions with HMG-CoA reductase inhibitors

The HMG-CoA reductase inhibitors (statins) are effective in both the primary and secondary prevention of ischaemic heart disease. As a group, these drugs are well tolerated apart from two uncommon but potentially serious adverse effects: elevation of liver enzymes and skeletal muscle abnormalities, which range from benign myalgias to life-threatening rhabdomyolysis. Adverse effects with statins are frequently associated with drug interactions because of their long-term use in older patients who are likely to be exposed to polypharmacy. The recent withdrawal of cerivastatin as a result of deaths from rhabdomyolysis illustrates the clinical importance of such interactions. Drug interactions involving the statins may have either a pharmacodynamic or pharmacokinetic basis, or both. As these drugs are highly extracted by the liver, displacement interactions are of limited importance. The cytochrome P450 (CYP) enzyme system plays an important part in the metabolism of the statins, leading to clinically relevant interactions with other agents, particularly cyclosporin, erythromycin, itraconazole, ketoconazole and HIV protease inhibitors, that are also metabolised by this enzyme system. An additional complicating feature is that individual statins are metabolised to differing degrees, in some cases producing active metabolites. The CYP3A family metabolises lovastatin, simvastatin, atorvastatin and cerivastatin, whereas CYP2C9 metabolises fluvastatin. Cerivastatin is also metabolised by CYP2C8. Pravastatin is not significantly metabolised by the CYP system. In addition, the statins are substrates for P-glycoprotein, a drug transporter present in the small intestine that may influence their oral bioavailability. In clinical practice, the risk of a serious interaction causing myopathy is enhanced when statin metabolism is markedly inhibited. Thus, rhabdomyolysis has occurred following the coadministration of cyclosporin, a potent CYP3A4 and P-glycoprotein inhibitor, and lovastatin. Itraconazole has been shown to increase exposure to simvastatin and its active metabolite by at least 10-fold. Pharmacodynamically, there is an increased risk of myopathy when statins are coprescribed with fibrates or nicotinic acid. This occurs relatively infrequently, but is particularly associated with the combination of cerivastatin and gemfibrozil. Statins may also alter the concentrations of other drugs, such as warfarin or digoxin, leading to alterations in effect or a requirement for clinical monitoring. Knowledge of the pharmacokinetic properties of the statins should allow the avoidance of the majority of drug interactions. If concurrent therapy with known inhibitors of statin metabolism is necessary, the patient should be monitored for signs and symptoms of myopathy or rhabdomyolysis and the statin should be discontinued if necessary.

How well tolerated are lipid-lowering drugs?

It has been clearly established that lipid-lowering treatments [such as 3-hydroxyl-3-methylglutamyl coenzyme A reductase inhibitors ('statins') or fibrates] can reduce cardiovascular events, and with one of the statins even total mortality, in high-risk populations. Intervention studies have not included the very old, but it is generally assumed that this patient group would benefit from these treatments to an extent similar to younger patients. Worries about the associations seen in observational studies between low cholesterol levels and cancer, cerebral haemorrhage or mood and behaviour change have been largely overcome by findings from the latest large drug intervention trials, which do not show any increase in these conditions with statin or fibrate treatments. The common adverse effects associated with these drugs are relatively mild and often transient in nature. Potentially more serious adverse effects, which are more clearly related to drug treatment and are probably dose-dependent, include elevations in hepatic transaminase levels and myopathy; however, these effects are uncommon and generally resolve rapidly when treatment is stopped. The risk of myopathy with fibrate treatment is increased in patients with renal impairment, and the risk of myopathy with statin treatment increases with co-administration of drugs that inhibit statin metabolism or transport. Other adverse effects are related to specific drugs, for example, clofibrate is associated with an increased risk of gallstones. Studies in elderly patients have not shown an increased risk of adverse effects with lipid-lowering drugs compared with younger patients, but in clinical practice there may be some increased risk, particularly with regards to drug interactions. Therefore, lipid-lowering drugs should be administered with extra caution to elderly patients.

HMG-CoA reductase inhibitors and the malignant cell: the statin family of drugs as triggers of tumor-specific apoptosis

The statin family of drugs target HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway, and have been used successfully in the treatment of hypercholesterolemia for the past 15 years. Experimental evidence suggests this key biochemical pathway holds an important role in the carcinogenic process. Moreover, statin administration in vivo can provide an oncoprotective effect. Indeed, in vitro studies have shown the statins can trigger cells of certain tumor types, such as acute myelogenous leukemia, to undergo apoptosis in a sensitive and specific manner. Mechanistic studies show bcl-2 expression is down-regulated in transformed cells undergoing apoptosis in response to statin exposure. In addition, the apoptotic response is in part due to the depletion of the downstream product geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate or other products of the mevalonate pathway including cholesterol. Clinically, preliminary phase I clinical trials have shown the achievable plasma concentration corresponds to the dose range that can trigger apoptosis of tumor types in vitro. Moreover, little toxicity was evident in vivo even at high concentrations. Clearly, additional clinical trials are warranted to further assess the safety and efficacy of statins as novel and immediately available anti-cancer agents. In this article, the experimental evidence supporting a role for the statin family of drugs to this new application will be reviewed.

Dose dependency of fluvastatin pharmacokinetics in serum determined by reversed phase HPLC

BACKGROUND

Fluvastatin is an inhibitor of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, effectively lowering serum cholesterol concentrations. A high-performance liquid chromatography (HPLC) assay was developed that determined the pharmacokinetics of fluvastatin in healthy individuals after administration of 40 and 80 mg fluvastatin.

METHODS

The method was linear for serum concentrations between 10 ng/mL and 5,000 ng/mL, showing good coefficients of variations and sample stability. After administration of 40 mg fluvastatin, the mean values of the area under the serum concentration vs time curve (AUC), the maximum serum drug concentration (C(max)), the time to reach C(max) (t(max)), and the serum elimination half-life time were 528.5 +/-358.8 ng/mL x h, 149.6 +/-56.0 ng/mL, 60.0 +/-30.0 minutes, and 108.0 +/-67.9 minutes, respectively. The corresponding values for a dose of 80 mg fluvastatin were 1417.7 +/-879.2 ng/mL x h, 1024.7 +/-1085.1 ng/mL, 60.0 +/-21.2 minutes, and 106.0 +/-73.6 minutes, respectively. Doubling of the dose from 40 mg to 80 mg caused an overproportional increase of AUC and C(max).

RESULTS AND CONCLUSION

Results suggest that the measurement of fluvastatin serum concentrations by means of HPLC provides reliable data within the broad range of physiological serum concentrations. The pharmacokinetic data after administration of high doses (80 mg) showed an overproportional increase of AUC and C(max), suggesting a saturation of the hepatic first-pass effect. Thus, in patients treated with additional substances interfering with fluvastatin metabolism, fluvastatin serum concentrations should be analyzed.

Quantitative determination of pravastatin and its biotransformation products in human serum by turbo ion spray LC/MS/MS

A sensitive, specific, accurate and reproducible analytical method was developed and validated to quantify pravastatin (Prav), pravastatin-d5 (Prav-d5), SQ-31906, SQ-31906-d5, and pravastatin lactone (Prav-Lac) in human serum samples. Serum samples (0.5 ml) were acidified and extracted by a solid-phase extraction procedure to isolate all five analytes from human serum. Sample extracts were reconstituted and analyzed by turbo ion spray liquid chromatography/tandem mass spectrometry (LC/MS/MS) in the positive ion mode. The total run time was 9 min between injections. The assay demonstrated a lower limit of quantitation (LLQ) of 0.5 ng/ml for all five analytes. The calibration curves were linear from 0.5 ng ml to 100 ng/ml for all five analytes. The coefficients of determination of all calibration curves were > or = 0.999. Precision and accuracy quality control (QC) samples were prepared at concentrations of 2, 30, 80, and 500 ng/ml for all analytes. The intra-assay and inter-assay precision calculated from QC samples were within 8%, for all analytes. The inter-assay accuracy calculated from QC samples was within 8% for all analytes. The extraction recoveries were > or = 90% for all analytes. Benchtop stability experiments in an ice-water bath ( < or = 10 degrees C) demonstrated that over time, Prav-Lac hydrolyzes to Prav in serum. Prav, Prav-d5, SQ-31906, and SQ-31906-d5 were stable under these conditions for up to 24 h. Hydrolysis was minimized by buffering the serum to pH 4.5 and maintaining the serum sample in an ice-water bath. All analytes were stable after three freeze/thaw cycles and in reconstitution solution after 1 week at 4 degrees C. Stability of all analytes in human serum was demonstrated after storage at -70 degrees C for 77 days. The benchtop (< or = 10 degrees C) stability of pooled study samples was also investigated and the results were comparable to those obtained from serum QC samples.

Current perspectives on statins

Statins (HMG-CoA reductase inhibitors) are used widely for the treatment of hypercholesterolemia. They inhibit HMG-CoA reductase competitively, reduce LDL levels more than other cholesterol-lowering drugs, and lower triglyceride levels in hypertriglyceridemic patients. Statins are well tolerated and have an excellent safety record. Clinical trials in patients with and without coronary heart disease and with and without high cholesterol have demonstrated consistently that statins reduce the relative risk of major coronary events by approximately 30% and produce a greater absolute benefit in patients with higher baseline risk. Proposed mechanisms include favorable effects on plasma lipoproteins, endothelial function, plaque architecture and stability, thrombosis, and inflammation. Mechanisms independent of LDL lowering may play an important role in the clinical benefits conferred by these drugs and may ultimately broaden their indication from lipid-lowering to antiatherogenic agents.

New insights into the pharmacodynamic and pharmacokinetic properties of statins

The beneficial effects of statins are assumed to result from their ability to reduce cholesterol biosynthesis. However, because mevalonic acid is the precursor not only of cholesterol, but also of many nonsteroidal isoprenoid compounds, inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase may result in pleiotropic effects. It has been shown that several statins decrease smooth muscle cell migration and proliferation and that sera from fluvastatin-treated patients interfere with its proliferation. Cholesterol accumulation in macrophages can be inhibited by different statins, while both fluvastatin and simvastatin inhibit secretion of metalloproteinases by human monocyte-derived macrophages. The antiatherosclerotic effects of statins may be achieved by modifying hypercholesterolemia and the arterial wall environment as well. Although statins rarely have severe adverse effects, interactions with other drugs deserve attention. Simvastatin, lovastatin, cerivastatin, and atorvastatin are biotransformed in the liver primarily by cytochrome P450-3A4, and are susceptible to drug interactions when co-administered with potential inhibitors of this enzyme. Indeed, pharmacokinetic interactions (e.g., increased bioavailability), myositis, and rhabdomyolysis have been reported following concurrent use of simvastatin or lovastatin and cyclosporine A, mibefradil, or nefazodone. In contrast, fluvastatin (mainly metabolized by cytochrome P450-2C9) and pravastatin (eliminated by other metabolic routes) are less subject to this interaction. Nevertheless, a 5- to 23-fold increase in pravastatin bioavailability has been reported in the presence of cyclosporine A. In summary, statins may have direct effects on the arterial wall, which may contribute to their antiatherosclerotic actions. Furthermore, some statins may have lower adverse drug interaction potential than others, which is an important determinant of safety during long-term therapy.

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

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

Effects of liver disease on pharmacokinetics. An update

Liver disease can modify the kinetics of drugs biotransformed by the liver. This review updates recent developments in this field, with particular emphasis on cytochrome P450 (CYP). CYP is a rapidly expanding area in clinical pharmacology. The information currently available on specific isoforms involved in drug metabolism has increased tremendously over the latest years, but knowledge remains incomplete. Studies on the effects of liver disease on specific isoenzymes of CYP have shown that some isoforms are more susceptible than others to liver disease. A detailed knowledge of the particular isoenzyme involved in the metabolism of a drug and the impact of liver disease on that enzyme can provide a rational basis for dosage adjustment in patients with hepatic impairment. The capacity of the liver to metabolise drugs depends on hepatic blood flow and liver enzyme activity, both of which can be affected by liver disease. In addition, liver failure can influence the binding of a drug to plasma proteins. These changes can occur alone or in combination; when they coexist their effect on drug kinetics is synergistic, not simply additive. The kinetics of drugs with a low hepatic extraction are sensitive to hepatic failure rather than to liver blood flow changes, but drugs having a significant first-pass effect are sensitive to alterations in hepatic blood flow. The drugs examined in this review are: cardiovascular agents (angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, calcium antagonists, ketanserin, antiarrhythmics and hypolipidaemics), diuretics (torasemide), psychoactive and anticonvulsant agents (benzodiazepines, flumazenil, antidepressants and tiagabine), antiemetics (metoclopramide and serotonin antagonists), antiulcers (acid pump inhibitors), anti-infectives and antiretroviral agents (grepafloxacin, ornidazole, pefloxacin, stavudine and zidovudine), immunosuppressants (cyclosporin and tacrolimus), naltrexone, tolcapone and toremifene. According to the available data, the kinetics of many drugs are altered by liver disease to an extent that requires dosage adjustment; the problem is to quantify the required changes. Obviously, this requires the evaluation of the degree of hepatic impairment. At present there is no satisfactory test that gives a quantitative measure of liver function and its impairment. A critical evaluation of these methods is provided. Guidelines providing a rational basis for dosage adjustment are illustrated. Finally, it is important to consider that liver disease not only affects pharmacokinetics but also pharmacodynamics. This review also examines drugs with altered pharmacodynamics.

The pravastatin-induced decrease of biliary cholesterol secretion is not directly related to an inhibition of cholesterol synthesis in humans

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been reported to suppress biliary cholesterol secretion and saturation. It remains unproven whether this is mediated by inhibition of cholesterol synthesis. Therefore, the effect of a long-term administration of pravastatin on cholesterogenesis and on biliary lipid secretion was investigated in seven healthy volunteers. Placebo or 40 mg of pravastatin were taken daily at bedtime for 5 weeks using a double-blind crossover design. During the last week, 12 hours after the last drug intake 0.04 mmol [1-13C]acetate/kg. h and 0.5 g polyethylene glycol 4,000/h were infused intraduodenally for 15 hours. Plasma and duodenal bile samples were collected hourly. Thereafter, the decay of [13C]labeled plasma cholesterol was measured during the following 3 days. The fractional and absolute syntheses of plasma and biliary cholesterol were determined by gas chromatography mass spectrometry using mass isotopomer distribution analysis. At the end of the pravastatin period plasma total and low-density lipoprotein (LDL) cholesterol had decreased by 20% and 24%, respectively. Similarly, pravastatin suppressed biliary secretion rates of cholesterol, total bile acids and phospholipids (P <.05) by 46%, 36%, and 51%. As a consequence, cholesterol saturation index remained unchanged. However, fractional syntheses of cholesterol were comparable (P >.05) on placebo compared with pravastatin with 3.1% versus 4.0% in plasma and 4.3% versus 5.2% in bile after 15 hours, respectively. The mean absolute synthesis rates amounted to 0.3 mg/kg/h on placebo versus 0.4 on pravastatin (P >. 05). In conclusion, the pravastatin-induced reduction of biliary cholesterol secretion is not directly related to an inhibition of cholesterol synthesis.

Metabolism and drug interactions of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in transplant patients: are the statins mechanistically similar?

3-Hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.88) inhibitors are the most effective drugs to lower cholesterol in transplant patients. However, immunosuppressants and several other drugs used after organ transplantation are cytochrome P4503A (CYP3A, EC 1.14.14.1) substrates. Pharmacokinetic interaction with some of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, specifically lovastatin and simvastatin, leads to an increased incidence of muscle skeletal toxicity in transplant patients. It is our objective to review the role of drug metabolism and drug interactions of lovastatin, simvastatin, pravastatin, fluvastatin, atorvastatin, and cerivastatin. In the treatment of transplant patients, from a drug interaction perspective, pravastatin, which is not significantly metabolized by CYP enzymes, and fluvastatin, presumably a CYP2C9 substrate, compare favorably with the other statins for which the major metabolic pathways are catalyzed by CYP3A.

Erythromycin and verapamil considerably increase serum simvastatin and simvastatin acid concentrations

OBJECTIVE

To study the effects of erythromycin and verapamil on the pharmacokinetics of simvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase.

METHODS

A randomized, double-blind crossover study was performed with three phases separated by a washout period of 3 weeks. Twelve young, healthy volunteers took orally either 1.5 gm/day erythromycin, 240 mg/day verapamil, or placebo for 2 days. On day 2, 40 mg simvastatin was administered orally. Serum concentrations of simvastatin, simvastatin acid, erythromycin, verapamil, and norverapamil were measured for up to 24 hours.

RESULTS

Erythromycin and verapamil increased mean peak serum concentration (Cmax) of unchanged simvastatin 3.4-fold (p < 0.001) and 2.6-fold (p < 0.05) and the area under the serum simvastatin concentration-time curve from time zero to 24 hours [AUC(0-24)] 6.2-fold (p < 0.001) and 4.6-fold (p < 0.01). Erythromycin increased the mean Cmax of active simvastatin acid fivefold (p < 0.001) and the AUC(0-24) 3.9-fold (p < 0.001). Verapamil increased the Cmax of simvastatin acid 3.4-fold (p < 0.001) and the AUC(0-24) 2.8-fold (p < 0.001). There was more than tenfold interindividual variability in the extent of simvastatin interaction with both erythromycin and verapamil.

CONCLUSIONS

Both erythromycin and verapamil interact considerably with simvastatin, probably by inhibiting its cytochrome P450 (CYP) 3A4-mediated metabolism. Concomitant administration of erythromycin, verapamil, or other potent inhibitors of CYP3A4 with simvastatin should be avoided. As an alternative, the dosage of simvastatin should be reduced considerably, that is, by about 50% to 80%, at least when a simvastatin dosage higher than 20 mg/day is used. Possible adverse effects, such as elevation of creatine kinase level and muscle tenderness, should be closely monitored when such combinations are used.

Effect of itraconazole on the pharmacokinetics of atorvastatin

BACKGROUND

Itraconazole, a potent inhibitor of CYP3A4, increases the risk of skeletal muscle toxicity of some 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors by increasing their serum concentrations. The aim of this study was to characterize the effect of itraconazole on the pharmacokinetics of atorvastatin, a new HMG-CoA reductase inhibitor that is metabolized at least in part by CYP3A4.

METHODS

In a randomized, double-blind, two-phase crossover study, 10 healthy volunteers took 200 mg itraconazole or matched placebo orally once daily for 4 days. On day 4, 40 mg atorvastatin was administered orally, and a further dose of 200 mg itraconazole or placebo was taken 24 hours after atorvastatin intake. Serum concentrations of atorvastatin acid, atorvastatin lactone, 2-hydroxyatorvastatin acid and lactone, 4-hydroxyatorvastatin acid and lactone, active and total HMG-CoA reductase inhibitors, itraconazole, and hydroxyitraconazole were measured up to 72 hours.

RESULTS

Itraconazole increased the area under the concentration--time curve from time zero to 72 hours [AUC(0-72)] and the elimination half-life of atorvastatin acid about threefold (p < 0.001), whereas the peak serum concentration was not significantly changed. The AUC(0-72) of atorvastatin lactone was increased about fourfold (p < 0.001), and the peak serum concentration and half-life were increased more than twofold (p < 0.01). Itraconazole decreased the peak serum concentration and AUC(0-72) of 2-hydroxyatorvastatin acid (p < 0.01) and 2-hydroxyatorvastatin lactone (p < 0.01). Itraconazole significantly (p < 0.01) increased the half-life of 2 hydroxyatorvastatin lactone. The AUC(0-72) values of active and total HMG-CoA reductase inhibitors were increased 1.6-fold (p < 0.001) and 1.7-fold (p < 0.001), respectively.

CONCLUSIONS

Itraconazole has a significant interaction with atorvastatin. The mechanism of increased serum concentrations of atorvastatin and HMG-CoA reductase inhibitors is inhibition of CYP3A4-mediated metabolism of atorvastatin and its metabolites by itraconazole. Concomitant use of itraconazole and other potent inhibitors of CYP3A4 with atorvastatin should be avoided or the dose of atorvastatin should be reduced accordingly.

Grapefruit juice greatly increases serum concentrations of lovastatin and lovastatin acid

BACKGROUND

Grapefruit juice increases the bioavailability of several drugs known to be metabolized by CYP3A4. We wanted to investigate a possible interaction of grapefruit juice with lovastatin, a cholesterol-lowering agent that is partially metabolized by CY P3A4.

METHODS

An open, randomized, two-phase crossover study with an interval of 2 weeks between the phases was carried out. Ten healthy volunteers took either 200 ml double-strength grapefruit juice or water orally three times a day for 2 days. On day 3, each subject ingested 80 mg lovastatin with either 200 ml grapefruit juice or water, and an additional dose of 200 ml was ingested 1/2 and 1 1/2 hours after lovastatin intake. Serum concentrations of lovastatin and lovastatin acid were measured up to 12 hours.

RESULTS

Grapefruit juice greatly increased the serum concentrations of both lovastatin and lovastatin acid. The mean peak serum concentration (Cmax) of lovastatin was increased about 12-fold (range, 5.2-fold to 19.7-fold; p < 0.001) and the area under the concentration-time curve [AUC(0-12)] was increased 15-fold (range, 5.7-fold to 26.3-fold; p < 0.001) by grapefruit juice. The mean Cmax and AUC(0-12) of lovastatin acid were increased about fourfold (range, 1.8-fold to 11.5-fold; p < 0.001) and fivefold (range, 2.4-fold to 23.3-fold; p < 0.001) by grapefruit juice, respectively. The half-lives of lovastatin and lovastatin acid remained unchanged.

CONCLUSIONS

Grapefruit juice can greatly increase serum concentrations of lovastatin and its active metabolite, lovastatin acid, probably by preventing CYP3A4-mediated first-pass metabolism in the small intestine. The concomitant use of grapefruit juice with lovastatin and simvastatin should be avoided, or the dose of these 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors should be reduced accordingly.

Simvastatin but not pravastatin is very susceptible to interaction with the CYP3A4 inhibitor itraconazole

BACKGROUND

Itraconazole increases the risk of skeletal muscle toxicity of some 3-hydroxy-3-methylglutaryl coenzyme A' (HMG-CoA) reductase inhibitors by increasing their serum concentrations. We studied possible interactions of itraconazole with simvastatin and pravastatin.

METHODS

Two randomized, double-blind, two-phase crossover studies were performed with use of an identical design, one with simvastatin (study I) and one with pravastatin (study II). In both studies, 10 healthy volunteers received either 200 mg itraconazole or placebo orally once a day for 4 days. On day 4, each subject ingested a single 40 mg dose of simvastatin (study I) or pravastatin (study II). Serum concentrations of simvastatin, simvastatin acid, pravastatin, HMG-CoA reductase inhibitors, itraconazole, and hydroxyitraconazole were determined.

RESULTS

In study I, itraconazole increased the peak serum concentrations (Cmax) and the areas under the serum concentration-time curve [AUC(0-infinity)] of simvastatin and simvastatin acid at least tenfold (p < 0.001). The Cmax and AUC(0-infinity) of total simvastatin acid (naive simvastatin acid plus that derived by hydrolysis of the lactone) were increased 17-fold and 19-fold (p < 0.001), respectively, and the half-life (t1/2) was increased by 25% (p < 0.05). The AUC(0-infinity) of HMG-CoA reductase inhibitors was increased fivefold (p < 0.001) and the Cmax and t1/2 were increased threefold (p < 0.001). In study II, itraconazole slightly increased the AUC(0-infinity) and Cmax of pravastatin, but the changes were statistically nonsignificant (p = 0.052 and 0.172, respectively). The t1/2 was not altered. The AUC(0-infinity) and Cmax of HMG-CoA reductase inhibitors were increased less than twofold (p < 0.05 and p = 0.063, respectively) by itraconazole. There were no differences in the serum concentrations of itraconazole and hydroxyitraconazole between studies I and II.

CONCLUSIONS

Itraconazole greatly increased serum concentrations of simvastatin, simvastatin acid, and HMG CoA reductase inhibitors, probably by inhibiting CYP3A-mediated metabolism, but it had only a minor effect on pravastatin. Concomitant use of potent inhibitors of CYP3A with simvastatin should be avoided or its dosage should be greatly reduced.

A randomized trial of the effects of atorvastatin and niacin in patients with combined hyperlipidemia or isolated hypertriglyceridemia. Collaborative Atorvastatin Study Group

BACKGROUND

To assess the lipid-lowering effects and safety of atorvastatin and niacin in patients with combined hyperlipidemia or isolated hypertriglyceridemia.

METHODS

We performed a randomized, open-label, parallel-design, active-controlled, study in eight centers in the United States. We enrolled 108 patients with total cholesterol (TC) of > or =200 mg/dL, serum triglycerides (TG) > or =200 and < or =800 mg/dL, and apolipoprotein B (apo B) > or =110 mg/dL. Patients were randomly assigned to receive atorvastatin 10 mg once daily (n=55) or immediate-release niacin 1 g three times daily for 12 weeks (n=53). Patients were stratified based on low-density lipoprotein cholesterol (LDL-C): Patients with LDL-C > or =135 mg/dL were considered to have combined hyperlipidemia and patients with LDL-C <135 mg/dL were considered to have isolated hypertriglyceridemia. The primary outcome measure was percent change from baseline in LDL-C. Other lipid levels were evaluated as secondary parameters.

RESULTS

Atorvastatin reduced LDL-C 30% and TC 26% from baseline, and increased high-density lipoprotein cholesterol (HDL-C) 4%. Total TG were reduced 17%. Niacin reduced LDL-C 2%, TC 7%, increased HDL-C 25%, and reduced total TG 29% from baseline. There was a significant difference in LDL-C reduction, the primary efficacy parameter, between the two treatment groups (P <0.05, favoring atorvastatin), as well as a significant difference in the improvement in HDL-C (P <0.05, favoring niacin). The effect of atorvastatin was relatively consistent between patients with combined hyperlipidemia and isolated hypertriglyceridemia, whereas there was more variability between these strata in the niacin treatment group. Atorvastatin was better tolerated than niacin.

CONCLUSION

Atorvastatin may allow patients with combined hyperlipidemia to be treated with monotherapy and offers an efficacious and well-tolerated alternative to niacin for the treatment of patients with isolated hypertriglyceridemia.

Mevalonate-dependent inhibition of transendothelial migration and chemotaxis of human peripheral blood neutrophils by pravastatin

Pravastatin, a hydrophilic inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, has been reported to beneficially affect atherogenesis, plaque stability, and transient myocardial ischemia in significant coronary artery disease by influencing lipid metabolism and by intracellular signaling via mevalonate pathway products other than cholesterol. Leukocytes are implicated to play a pathophysiological role in these events. We were interested in finding out whether pravastatin could affect transendothelial migration (TEM), chemotaxis, and respiratory burst activity of the neutrophil ex vivo. In addition, effects on monocyte and T-lymphocyte chemotaxis were tested. For TEM assays, monolayers of human umbilical vein endothelial cells (HUVECs) were grown to confluence on polycarbonate filters bearing 5-microns pores in Transwell (Costar) culture plate inserts. Chemotaxis experiments were performed using modified Boyden chambers with cellulose nitrate micropore filters. Respiratory burst activity was measured fluorometrically. Treatment of neutrophils and monocytes with pravastatin at 2 to 200 mumol/L and 10 to 1000 mumol/L, respectively, significantly decreased chemotaxis triggered by fMet-Leu-Phe. This effect was abolished in the presence of mevalonic acid (500 mumol/L); no effect of pravastatin was seen on T-lymphocyte chemotaxis triggered by interleukin-8. Preincubation of neutrophils with pravastatin (200 mumol/L) also resulted in a significant reduction in the number of neutrophils that transmigrated a tumor necrosis factor-stimulated or lipopolysaccharide-stimulated HUVEC monolayer. At none of the concentrations tested (2 pmol/L to 200 mumol/L) did pravastatin affect neutrophil respiratory burst activity. We conclude that pravastatin may alter monocyte chemotaxis and neutrophil-endothelial interactions in migratory responses at concentrations obtained in vivo with cholesterol-lowering doses.

Atorvastatin. A review of its pharmacology and therapeutic potential in the management of hyperlipidaemias

Atorvastatin is a synthetic HMG-CoA reductase inhibitor which lowers plasma cholesterol levels by inhibiting endogenous cholesterol synthesis. It also reduces triglyceride levels through an as yet unproven mechanism. Dose-dependent reductions in total cholesterol, low density lipoprotein (LDL)-cholesterol and triglyceride levels have been observed with atorvastatin in patients with hypercholesterolaemia and in patients with hypertriglyceridaemia. In large trials involving patients with hypercholesterolaemia, atorvastatin produced greater reductions in total cholesterol, LDL-cholesterol, apolipoprotein B and triglyceride levels than lovastatin, pravastatin and simvastatin. In patients with primary hypercholesterolaemia, the combination of atorvastatin and colestipol tended to produce larger reductions in LDL-cholesterol levels and smaller reductions in triglyceride levels than atorvastatin monotherapy. Although atorvastatin induced smaller reductions in triglyceride levels and more modest increases in high density lipoprotein (HDL)-cholesterol levels than either fenofibrate or nicotinic acid in patients with combined hyperlipidaemia, it produced larger reductions in total cholesterol and LDL-cholesterol. As with other HMG-CoA reductase inhibitors, the most frequently reported adverse events associated with atorvastatin are gastrointestinal effects. In comparative trials, atorvastatin had a similar adverse event profile to that of other HMG-CoA reductase inhibitors. Clinical data with atorvastatin are limited at present. However, with its ability to markedly reduce LDL-cholesterol levels, atorvastatin is likely to join other members of its class as a first-line agent for the treatment of patients with hypercholesterolaemia, if changes in lipid levels with atorvastatin convert to reductions in CHD mortality and morbidity. Atorvastatin may be particularly suitable for patients with heterozygous or homozygous familial hypercholesterolaemia because of the marked reductions in LDL-cholesterol experienced with the drug. Additionally, because of its triglyceride-lowering properties, atorvastatin appears to have the potential to become an appropriate treatment for patients with combined hyperlipidaemia or hypertriglyceridaemia.