Comparative tolerability of the HMG-CoA reductase inhibitors

Efficacy and safety of high-dose pravastatin in hypercholesterolemic patients with well-compensated chronic liver disease: Results of a prospective, randomized, double-blind, placebo-controlled, multicenter trial

The hepatotoxic potential of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in patients with underlying chronic liver disease remains controversial. We performed a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial that compared pravastatin (80 mg) to a placebo administered once daily to hypercholesterolemic subjects greater than 18 years of age with at least a 6-month history of compensated chronic liver disease and with a low-density lipoprotein cholesterol (LDL-C) level greater than or equal to 100 mg/dL and a triglyceride (TG) level lower than 400 mg/dL. The efficacy was determined by the percentage change in LDL-C [along with the total cholesterol (TC), high-density lipoprotein cholesterol, and TG] from the baseline to week 12. The safety was analyzed by the proportion of subjects who developed at least 1 alanine aminotransferase (ALT) value greater than or equal to 2 times the upper limit of normal for those with normal ALT at the baseline or a doubling of the baseline ALT for those with elevated ALT at the baseline during 36 weeks of treatment. A total of 630 subjects were screened, and 326 subjects were randomized; nonalcoholic fatty liver disease was present in 64%, and chronic hepatitis C was present in 23%. In the intent-to-treat population, pravastatin (80 mg/day) significantly lowered the mean LDL-C, TC, and TG values at week 12 and at other times (weeks 4, 8, 24, and 36) in comparison with the placebo. The incidence of subjects who met the primary prespecified ALT event definition was lower in the pravastatin group at all times over the 36 weeks of therapy in comparison with the placebo group, although the difference was not statistically significant. No differences were seen on the basis of the baseline ALT values or among the different liver disease groups.

CONCLUSION

High-dose pravastatin (80 mg/day) administered to hypercholesterolemic subjects with chronic liver disease significantly lowered LDL-C, TC, and TGs in comparison with the placebo and was safe and well tolerated. The concern over an increased potential for statin-induced hepatotoxicity in patients with chronic liver disease appears to be lessened on the basis of these results.

Effect of HMGCoA reductase inhibitors on cytochrome P450 expression in endothelial cell line

Endothelial cells and smooth muscle cells are the major cells that constitute blood vessels, and endothelial cells line the lumen of blood vessels. These 2 types of cells also play an integral role in the regional specialization of vascular structure. On the basis of these observations, we designed our study to investigate the effect of various statins on CYP expression in endothelial cells. 3-hydroxymethyl coenzyme A reductase inhibitors play an important role in vascular function. The majority of the statins available on the market show extensive metabolism by cytochrome P450 (CYP) enzymes. Both cell types are involved in the bioconversion of arachidonic acid into vasoactive compounds. The aim of this study was to demonstrate the effect of statins on cytochrome P450 expression in endothelial cells. Our results show that endothelial cells expressed both CYPs involved in epoxyeicosatrienoic acids (EETs) and hydroxyeicosatetraenoic acids (HETEs) production and the nuclear receptor implicated in cytochrome P450 regulation. Treatment of endothelial cells with lovastatin increased CYP2C9 expression. After 96 hours of treatment, fluvastatin and lovastatin clearly increased CYP2C9 protein level. CAR but not PXR was expressed in endothelial cells, indicating that the upregulating effect of statins on CYP2C9 in endothelial cells could be mediated through CAR only due to the lack of expression of PXR in these cells.

A multi-centre, randomised, double-blind 14-week extension study examining the long-term safety and efficacy profile of the ezetimibe/simvastatin combination tablet

The objective of this study was to compare the efficacy and safety profile of ezetimibe/simvastatin (EZE/SIMVA) tablet and SIMVA monotherapy. This was an extension study of a randomised, double-blind, placebo-controlled study in patients with primary hypercholesterolaemia. Protocol-compliant patients who completed the 12-week base study were eligible to enter a randomised, double-blind, 14-week extension study and were administered 1 of 8 daily treatments: EZE/SIMVA 10/10-, 10/20-, 10/40- or 10/80-mg, or SIMVA 10-, 20-, 40- or 80-mg. Patients receiving these treatments during the base study remained on the same treatment in the extension. Patients administered placebo or EZE 10-mg monotherapy during the base study were re-randomised to EZE/SIMVA 10/10 mg or SIMVA 80 mg. The primary analysis was mean per cent change in low-density lipoprotein cholesterol (LDL-C) from baseline to extension study end-point. Mean changes from baseline in LDL-C of -38.8% and -53.7% were observed for pooled SIMVA and pooled EZE/SIMVA respectively. The between treatment difference of -14.9% (95% confidence interval: -16.4, -13.3) was statistically significant (p < 0.001). The incremental LDL-C lowering effect of EZE/SIMVA compared with the corresponding dose of SIMVA alone was consistent across the dose range (p < 0.001 for each between-group comparison). More patients receiving EZE/SIMVA than SIMVA achieved LDL-C concentrations < 100 mg/dl and < 70 mg/dl (p < 0.001 for both goals). EZE/SIMVA was generally well tolerated with a safety profile similar to SIMVA monotherapy. There were no significant between-group differences in the incidences of clinically significant elevations in liver transaminase or creatine kinase levels. In conclusion, EZE/SIMVA had a comparable safety and tolerability profile and was more efficacious than SIMVA monotherapy for up to 6 months.

Lipid-lowering agents that cause drug-induced hepatotoxicity

The effort to reduce cardiovascular risk factors, including hyperlipidemia, has led to the increased use of lipid-lowering agents. Hyperlipidemic patients often have underlying fatty liver disease, however, and thus may have elevated and fluctuating liver biochemistries. Therefore, caution should be applied before attributing elevated liver tests to lipid-lowering agents. Data indicate that patients who have chronic liver disease and compensated cirrhosis should not be precluded from receiving statins to treat hyperlipidemia. Several recent studies and expert opinion currently fully endorse statin use in patients who have nonalcoholic fatty liver disease and other chronic liver disease if clinically indicated.

Current and novel therapies for the treatment of nonalcoholic steatohepatitis

The worldwide epidemic of obesity and the metabolic syndrome has made nonalcoholic fatty liver disease (NAFLD), one of the most important liver diseases of our time. NAFLD is now the commonest cause of abnormal liver test results in industrialized countries and its incidence is rising. The current treatment of nonalcoholic steatohepatitis (NASH) has focused on lifestyle modification to achieve weight loss and modification of risk factors, such as insulin resistance, dyslipidemia, and hyperglycemia associated with the metabolic syndrome. With our increasing understanding of the pathogenesis of NASH, have come a plethora of new pharmacologic options with great potential to modify the natural history of NAFLD and NASH. This article focuses on a number of novel molecular targets for the treatment of NASH as well as the evidence for currently available therapy. It should be noted, however, that in part because of the long natural history of NASH and NAFLD, no therapy to date has been shown to unequivocally alter liver-related morbidity and mortality in these patients.

Effectiveness and hepatotoxicity of statins in men seropositive for hepatitis C virus

STUDY OBJECTIVE

To evaluate the effectiveness and hepatotoxicity of statins in patients who are seropositive for hepatitis C virus (HCV).

DESIGN

Retrospective review of a registry of patients with HCV.

SETTING

Veterans Affairs Medical Center.

PATIENTS

One hundred forty-six male patients who were seropositive for HCV and had received statin therapy between January 1, 1995, and September 9, 2003.

MEASUREMENTS AND MAIN RESULTS

Demographic and clinical data were collected for each patient; lipid and alanine aminotransferase (ALT) levels at baseline (within 6 mo of starting a statin), at 3 and 6 months after starting a statin, and at long-term follow-up (mean 22 mo) were also recorded. The primary efficacy end point was a significant decrease from baseline to long-term follow-up low-density lipoprotein cholesterol (LDL) level; the primary safety end point was a significant increase from baseline in ALT level. The mean change in LDL level was a reduction of 22% (p<0.01). No significant increases in ALT levels were observed; only one patient discontinued therapy due to ALT level elevations greater than 3 times the upper limit of normal.

CONCLUSION

In men seropositive for HCV, statins were effective in reducing LDL levels and did not result in significant increases in ALT levels from baseline. Thus, statin therapy should be considered for patients with HCV who are at risk for coronary heart disease and do not have significantly elevated serum transaminase levels at baseline.

Safety of Rosuvastatin: Update on 16,876 Rosuvastatin-Treated Patients in a Multinational Clinical Trial Program

BACKGROUND

The safety and tolerability of rosuvastatin were assessed using data from 16,876 patients who received rosuvastatin 5-40 mg in a multinational phase II/III/IIIb/IV program, representing 25,670 patient-years of continuous exposure to rosuvastatin.

METHODS

An integrated database, consisting of 33 trials whose databases were locked up to and including September 16, 2005, was used to examine adverse events and laboratory data.

RESULTS

In placebo-controlled trials, adverse events irrespective of causality assessment occurred in 52.1% of patients receiving rosuvastatin 5-40 mg (n = 931) and 51.8% of patients receiving placebo (n = 483). In all controlled clinical trials with comparator statins, rosuvastatin 5-40 mg was associated with an adverse event profile similar to profiles for atorvastatin 10-80 mg, simvastatin 10-80 mg, and pravastatin 10-40 mg. Clinically significant elevations in alanine aminotransferase (> 3 times the upper limit of normal [ULN] on at least 2 consecutive occasions) were uncommon (< or = 0.2%) in the rosuvastatin and comparator statin groups. Elevated creatine kinase > 10 times ULN occurred in < or = 0.3% of patients receiving rosuvastatin or other statins. Myopathy (creatine kinase > 10 times ULN with muscle symptoms) possibly related to treatment occurred in 0.03% of patients taking rosuvastatin at doses < or = 40 mg. The frequency of dipstick-positive proteinuria at rosuvastatin doses < or = 20 mg was comparable to that seen with other statins, and the development of proteinuria was not predictive of acute or progressive renal disease. Both short- and long-term rosuvastatin treatment were associated with small increases in estimated glomerular filtration rate, with improvements appearing to be somewhat greater in those patients beginning treatment with greater renal impairment. In the phase II-IV program, no deaths were attributed to rosuvastatin; at doses of rosuvastatin < or = 40 mg, 1 case of rhabdomyolysis occurred in a patient who received rosuvastatin 20 mg and concomitant gemfibrozil treatment.

CONCLUSION

In summary, rosuvastatin was well tolerated by a broad range of patients with dyslipidemia, and its safety profile was similar to those of comparator statins investigated in the clinical program. (Nota bene: The clinical development program for rosuvastatin initially evaluated rosuvastatin doses up to 80 mg. Following completion of the phase III/IIIb program, a decision was made not to pursue marketing approval for the 80-mg dose because the additional lipid-modifying benefits of this dose did not justify the potential risks for use in the general population of patients with dyslipidemia.)

The use of statins in pediatrics: knowledge base, limitations, and future directions

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, effectively reduce coronary morbidity and mortality in high-risk adults. They are also some of the most widely prescribed medications in the United States. Their use in pediatrics, however, remains circumscribed. In this article we review the cholesterol hypothesis and focus on the knowledge base of the use of statins in adults and children. We pay particular attention to the known effects of statins in primary and secondary prevention of cardiovascular events. The toxicities of statins and their limitations in pediatrics are then considered. The use of statins in conjunction with noninvasive modalities of assessing atherosclerotic burden are also reviewed. Finally, we suggest methods to advance the use of statins in childhood that introduce their potential benefits to those individuals at highest risk for future events.

Tolerability of statins is not linked to CYP450 polymorphisms, but reduced CYP2D6 metabolism improves cholesteraemic response to simvastatin and fluvastatin

Statin therapy, although generally well tolerated, leads not infrequently to significant subjective and at times objective adverse effects (AEs), mainly of a muscular nature. The genetic background of these AEs is not clear and possibly side effects and lipid lowering efficacy may be linked. Aim of the study was a detailed evaluation of CYP450 and apolipoprotein E gene polymorphisms in two large series of age-sex matched patients with and without muscular side effects to statins. In a Clinical Institution specialised in lipid-lipoprotein disorders, 50 statin treated patients were selected, with subjective or objective statin-associated myopathy, evaluated using standardized forms. These were sex and age matched with 50 statin-treated patients from the same Clinic, without any subjective or objective complaints. DNA samples for the evaluation of CYP450 genetic polymorphisms and apo E genotypes were collected in order to assess correlations with both genetic polymorphisms and AEs, as well as with therapeutic efficacy. None of the assessed CYP450 polymorphisms appeared to be related to an increased incidence of AEs. The CYP2D6 *1/*4 and *4/4* poor metabolizer (PM) status was associated to a higher efficacy of statins metabolized by this system and, in addition, the apo E2 genotype was, in this series, linked to increased HDL-C levels after therapy. Patients with statin associated myopathy are not characterized by significantly different genotypes for the CYP450s responsible for statin metabolism. On the other hand, CYP2D6 PM status is associated to an increased efficacy of statins metabolized by this system.

New molecular therapy targets in acute myeloid leukemia

Despite improvements to acute myelogenous leukemia (AML) therapy during the last 25 years, the majority of patients still succumb to the disease. Thus, there remains an urgent need for further improvements in this field. The present chapter focuses on exciting areas of research in the field of AML therapy, including promising results with regards to recent improvements in our understanding of angiogenesis, tyrosine kinase signaling, farnesylation, cell cycling, modulation of gene expression, protein degradation, modulation of intracellular proteins, apoptosis, metabolism, and the possible retargeting of oncogenic proteins.

How safe is aggressive statin therapy?

The most recent guidelines of the National Cholesterol Education Program recommend more aggressive low-density lipoprotein cholesterol goals: <100 mg/dL for patients at moderate or high risk of cardiovascular disease, and <70 mg/dL for patients at very high risk. These lower goals are more likely to be achieved using the more powerful statins--atorvastatin, rosuvastatin, and simvastatin. Although statins are widely used, extensively studied, and known to have an excellent safety profile, the perception of many health care providers and patients is that safety concerns about the more efficacious statins, especially at high doses, limit their use. However, clinical data consistently support the view that adverse events are uncommon even when intensive therapy is used to reach aggressive low-density lipoprotein cholesterol goals. Overall, the more potent statins have similar safety profiles. The benefits of aggressive statin treatment in reducing the risk of cardiovascular events appear to far outweigh any potential risks of adverse events.

Simvastatin Promotes Neurite Outgrowth in the Presence of Inhibitory Molecules Found in Central Nervous System Injury

Statins (3-hydroxy-3-methylglutaryl-CoA [HMG-CoA] reductase inhibitors) inhibit the rate-limiting step in the mevalonate pathway, conversion of HMG-CoA to mevalonate, by competitive inhibition with the enzyme HMG-CoA reductase. Statins not only lower cholesterol levels, but are also thought to exert neuroprotective and neurogenic effects that may be beneficial in treating brain and spinal cord injuries. Data presented here illustrate that simvastatin enables neurite outgrowth in the presence of growth-inhibitory molecules commonly found at central nervous system (CNS) injury sites. To assess the effect of simvastatin on neurite outgrowth in the presence of inhibitory molecules present at CNS injury sites, rat embryonic cortex explants or postnatal spinal cord explants were grown on membrane filters prepared with alternating stripes of laminin and myelin/laminin. Immunostaining indicated that myelin stripes contain myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMgp), and Nogo, but do not contain chondroitin sulfate proteoglycan (CSPG). When control explants were grown in the presence of alternating stripes, neurite outgrowth preferentially extended in regions containing laminin only. In contrast, neurite outgrowth from explants grown in the presence of simvastatin was significantly less selective for laminin regions and was able to extend into regions containing myelin (p < 0.01). Simvastatin-induced effects were reversed by addition of mevalonate. Isoprenyl transferase inhibitors GGTI-286 and FTI-277, inhibitors of biochemical steps subsequent to HMG-CoA conversion to mevalonate, mimicked simvastatin- induced effects. These data suggest that simvastatin counteracts myelin-associated neurite outgrowth inhibition signals via mevalonate pathway inhibition, and may be beneficial in promoting axon regeneration in brain and spinal cord injury.

Safety Issues with Statin Therapy

OBJECTIVE

To describe the most important potential adverse effects related to statin therapy, discuss mechanisms of toxicity and drug interactions, and suggest approaches for enhancing safety with statin therapy.

DATA SOURCES

Large-scale clinical trials, government databases and papers, and recent studies of statin safety.

STUDY SELECTION

By the author.

DATA EXTRACTION

By the author.

DATA SYNTHESIS

The number of patients requiring intensive therapy with statins to achieve lipid goals is climbing, and as the number grows, so does the potential for adverse effects with these agents. The most detrimental adverse effects of statins are hepatotoxicity and myopathy. Liver dysfunction induced by statins is rare and usually mild, with asymptomatic transaminase elevation or acute cholecystitis. Progression to liver failure is exceedingly rare, and transaminase elevations is usually reversible with dose reduction. Statin-associated myopathy is generally a concern when patients have more than one risk factor for muscle syndromes, such as an elderly patient with poor renal function. Drug interactions represent an additional concern, especially for atorvastatin, lovastatin, and simvastatin, all of which are metabolized by the important 3A4 isoenzyme of the cytochrome P450 system of the liver.

CONCLUSION

The benefits of all available statins for the treatment or prevention of cardiovascular disease outweigh any potential risks of therapy. For patient groups most susceptible to adverse effects, such as the elderly and those on multiple medications, clinicians should consider the use of statins that are least likely to interact with other medications.

[Treatment of dyslipidemia: how and when to combine lipid lowering drugs]

Familial combined hyperlipidemia (FCH) is a frequent familial lipid disorder associated with insulin resistance, low HDL cholesterol, high triglycerides and cholesterol levels with variable phenotypes within the same family. FCH is linked to a high risk for cardiovascular diseases. Treatment goals for lipid abnormalities are changing in recent years. Lowering elevated levels of LDL e Non HDL-cholesterol levels are primary targets of therapy. Lower LDL-C than 70 mg/dL seems to be useful to lower cardiovascular risk in patients with very high risk. Many statins are available, with different potencies and drug interactions. Combination therapy of statins and bile acid sequestrants or ezitimibe may be necessary to further decrease LDL cholesterol levels in order to meet guideline goals. High triglycerides and low HDL cholesterol are also important goals in the treatment of these patients, and frequently statins alone are insufficient to normalize the lipid profile. Combination therapy with fibrates will further lower triglycerides and increase HDL cholesterol levels; this combination is also associated with higher incidence of myopathy and liver toxicity; appropriate evaluation of patients' risk and benefits is necessary. Association of statin/niacin seems be very useful in patients with FCH, especially as niacin is the best drug to increase HDL cholesterol; this association is not linked to a higher frequency of myopathy. Niacin causes flushing, that can in part be managed with use of aspirin and extended release forms (Niaspan); niacin also may increase plasma glucose and uric acid levels. Evaluation of risks and benefits for each patient is needed.

Pharmacogenomics of cholesterol-lowering therapy

The prevention of cardiovascular disease is critically dependent on lipid-lowering therapy, including 3-hydroxymethyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins), cholesterol absorption inhibitors, bile acid resins, fibrates, and nicotinic acid. Although these drugs are generally well tolerated, severe adverse effects can occur in a minority of patients. Furthermore, a subset of patients does not respond to cholesterol-lowering therapy with a reduction in coronary heart disease progression. Significant progress has been made in the identification of common DNA sequence variations in genes influencing the pharmacokinetics and pharmacodynamics of statins and in disease-modifying genes relevant for coronary heart disease (CHD). Among the most promising candidate genes for pharmacogenomic analysis of statin therapy are HMG-CoA reductase as a direct target gene and other genes modulating lipid and lipoprotein homeostasis. Based on data from pharmacogenetic trials, a combined analysis of multiple genetic variants in several genes is more likely to give significant results than single gene studies in small cohorts. In the future, pharmacogenomic testing may allow risk stratification of patients to avoid serious side effects and enable clinicians to select lipid-lowering drugs with the highest efficacy resulting in the best response to therapy.

Cutaneous melanoma: pathogenesis and rationale for chemoprevention

OBJECTIVE

To critically review aspects of melanoma pathogenesis that lend themselves to a chemoprevention strategy. To discuss potential candidate chemoprevention agents with an emphasis on the lipid lowering drugs, the statins, currently, the most promising agents.

DATA SOURCES

A retrospective review of the literature.

STUDY SELECTION

Studies included those relevant to melanoma pathogenesis, to the scientific rationale of chemoprevention, and pertinent epidemiologic, pre-clinical, and clinical studies. The referenced study designs and methodologies varied.

DATA EXTRACTION AND SYNTHESIS

Data were extracted by two reviewers, and the main results are presented in a quantitative descriptive manner.

CONCLUSION

Melanoma is a preventable disease by altering behavior (sun exposure) among at-risk individuals. There is also considerable evidence to suggest that melanoma development may be prevented or delayed by drugs of sufficiently low toxicity to make clinical trials of chemoprevention feasible and potentially successful. Among potential candidate agents, statins have compelling data for long-term safety and sufficient pre-clinical and clinical evidence for efficacy to justify their evaluation in well-designed trials in high-risk individuals, incorporating intermediate biologic endpoints.

Delineation of myotoxicity induced by 3-hydroxy-3-methylglutaryl CoA reductase inhibitors in human skeletal muscle cells

The 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (statins) are widely used and well tolerated cholesterol-lowering drugs. In rare cases, side effects occur in skeletal muscle, including myositis or even rhabdomyolysis. However, the molecular mechanisms are not well understood that lead to these muscle-specific side effects. Here, we show that statins cause apoptosis in differentiated human skeletal muscle cells. The prototypical representative of statins, simvastatin, triggered sustained intracellular Ca(2+) transients, leading to calpain activation. Intracellular chelation of Ca(2+) completely abrogated cell death. Moreover, ryanodine also completely prevented the simvastatin-induced calpain activation. Nevertheless, an activation of the ryanodine receptor by simvastatin could not be observed. Downstream of the calpain activation simvastatin led to a translocation of Bax to mitochondria in a caspase 8-independent manner. Consecutive activation of caspase 9 and 3 execute apoptotic cell death that was in part reversed by the coadministration of mevalonic acid. Conversely, the simvastatin-induced activation of calpain was not prevented by mevalonic acid. These data delineate the signaling cascade that leads to muscle injury caused by statins. Our observations also have implications for improving the safety of this important medication and explain to some extent why physical exercise aggravates skeletal muscle side effects.

Cancer risk among statin users: a population-based cohort study

Hydroxymethylglutaryl-CoA reductase inhibitors (statins) have been linked with potential chemopreventive effects; however, the data are conflicting. We conducted a population-based cohort study using data from the Prescription Database of North Jutland County and the Danish Cancer Registry for the period 1989-2002. In a study population of 334,754 county residents, we compared overall and site-specific cancer incidence among 12,251 statin users (> or =2 prescriptions) with cancer incidence among nonusers and users of other lipid-lowering drugs (n = 1,257). Statistical analyses were based on age-standardization and Poisson regression analysis, adjusting for age, gender, calendar period and use of NSAIDs, hormone replacement therapy and cardiovascular drugs. We identified 398 cancer cases among statin users during a mean follow-up period of 3.3 years (range 0-14 years). The age- and gender-standardized incidence rates of cancer overall were 596 per 100,000 person-years among statin users, 645 per 100,000 person-years among nonusers and 795 per 100,000 person-years among users of other lipid-lowering drugs. Adjusted rate ratios for cancer overall among statin users were 0.86 (95% CI, 0.78-0.95) compared to nonusers and 0.73 (95% CI, 0.55-0.98) compared to users of other lipid-lowering drugs. No significantly increased or decreased rate ratios were observed for any of the studied site-specific cancers (liver, colorectum, lung, breast, prostate, female genital organs and lymphatic and haematopoietic tissue), but most estimates tended to be less than 1.0. Stratification by duration of follow-up or number of prescriptions revealed no clear trends. In summary, individuals prescribed statins experienced a slightly reduced cancer incidence compared to population controls of nonusers and users of other lipid-lowering drugs. Larger and longer-term studies are needed to determine the potentially protective effect of statin use on cancer development.

Long-term safety and, tolerability profiles andlipid-modifying efficacy of ezetimibe coadministered with ongoing simvastatin treatment: A multicenter, randomized, double-blind, placebo-controlled, 48-week extension study

BACKGROUND

Ezetimibe (EZE) is a cholesterol-lowering drug that inhibits absorption of dietary and biliary cholesterol across the intestinal wall without affecting absorption of bile acids, fatty acids, fat-soluble vitamins, or triglycerides. It has a complementary mechanism of action to the statins, which inhibit cholesterol synthesis in the liver. Coadministration of EZE and statins provides inhibition of 2 sources of cholesterol, leading to greater reductions in low-density lipoprotein cholesterol (LDL-C) than with either agent alone.

OBJECTIVES

This study evaluated the long-term safety and tolerability profiles and lipid-modifying efficacy of treatment with EZE 10 mg/d plus simvastatin (SIMVA) 10, 20, 40, or 80 mg/d for 48 weeks in patients with primary hypercholesterolemia.

METHODS

This was an extension of a multicenter, double-blind, placebo (PBO)-controlled base study in which hypercholesterolemic patients were randomized to receive EZE 10 mg/d or PBO in addition to their current statin for 8 weeks. Patients who successfully completed the base study could enter the extension study if they were willing to switch from their current statin to an approximately equipotent dose of SIMVA for the 54-week study period. After a 6-week open-label SIMVA run-in phase, patients were rerandomized to receive EZE 10 mg/d or PBO in a 4:1 ratio, respectively, for 48 weeks. At each clinic visit, beginning at week 12, the dose of SIMVA was titrated upward until patients reached their National Cholesterol Education Program Adult Treatment Panel II LDL-C goal or the maximum SIMVA dose of 80 mg/d. Safety/tolerability and lipid efficacy parameters were assessed at 12-week intervals.

RESULTS

Of 433 patients entering the extension study, 355 were randomized to receive EZE and 78 were randomized to receive PBO. Baseline demographic characteristics and lipid levels were similar between treatment groups. Overall, coadministration of EZE + SIMVA was well tolerated. There were no clinically meaningful differences between the EZE and PBO groups with regard to the incidence of treatment-related adverse events (AEs) (19% vs 17%, respectively), discontinuations due to AEs (7% vs 10%), serious AEs (12% vs 17%), consecutive elevations in liver function tests > or =3 times the upper limit of normal (ULN) (0.3% vs 0%), or elevations in creatine kinase > or =10 times the ULN (both, 0%). As in the base study, LDL-C levels were significantly lower with the addition of EZE to SIMVA compared with the addition of PBO (-24% vs 3%; P < 0.001).

CONCLUSION

In these patients with primary hypercholesterolemia, EZE 10 mg/d added to ongoing SIMVA treatment for 48 weeks had a favorable safety and tolerability profile and was more efficacious than SIMVA monotherapy.

Pharmacologic treatment of type 2 diabetic dyslipidemia

Patients with diabetes mellitus have a higher risk for cardiovascular heart disease (CHD) than does the general population, and once they develop CHD, mortality is higher. Good glycemic control will reduce CHD only modestly in patients with diabetes. Therefore, reduction in all cardiovascular risks such as dyslipidemia, hypertension, and smoking is warranted. The focus of this article is on therapy for dyslipidemia in patients with type 2 diabetes. Patients with the metabolic syndrome (insulin resistance) share similarities with patients with type 2 diabetes and may have a comparable cardiovascular risk profile. Diabetic patients tend to have higher triglyceride, lower high-density lipoprotein cholesterol (HDL), and similar low-density lipoprotein cholesterol (LDL) levels compared with those levels in nondiabetic patients. However, diabetic patients tend to have a higher concentration of small dense LDL particles, which are associated with higher CHD risk. Current recommendations are for an LDL goal of less than 100 mg/dl (an option of < 70 mg/dl in very high-risk patients), an HDL goal greater than 40 mg/dl for men and greater than 50 mg/dl for women, and a triglyceride goal less than 150 mg/dl. Nonpharmacologic interventions (diet and exercise) are first-line therapies and are used with pharmacologic therapy when necessary. Lowering LDL levels is the first priority in treating diabetic dyslipidemia. Statins are the first drug choice, followed by resins or ezetimibe, then fenofibrate or niacin. If a single agent is inadequate to achieve lipid goals, combinations of the preceding Drugs may be used. For elevated triglyceride levels, hyperglycemia must be controlled first. If triglyceride or HDL levels remain uncontrolled, pharmacologic agents should be considered. Fibrates are slightly more effective than niacin in lowering triglyceride levels, but niacin increases HDL levels appreciably more than do fibrates. Unlike gemfibrozil, niacin selectively increases subfraction Lp A-I, a cardioprotective HDL. Niacin is distinct in that it has a broad spectrum of beneficial effects on lipids and atherogenic lipoprotein subfraction levels. Niacin produces additive results when used in combination therapy. Recent data suggest that lower dosages and newer formulations of niacin can be used safely in diabetic patients with good glycemic control. Current evidence and guidelines mandate that diabetic dyslipidemia be treated aggressively, and lipid goals can be achieved in most patients with diabetes when all available products are considered and, if necessary, used in combination.

The Effect of HMG-CoA Reductase Inhibitors on Coenzyme Q10

The HMG-CoA reductase inhibitors, also known as statins, have an enviable safety profile; however, myotoxicity and to a lesser extent hepatotoxicity have been noted in some patients following treatment. Statins target several tissues, depending upon their lipophilicity, where they competitively inhibit HMG-CoA reductase, the rate-limiting enzyme for mevalonic acid synthesis and subsequently cholesterol biosynthesis. HMG-CoA reductase is also the first committed rate-limiting step for the synthesis of a range of other compounds including steroid hormones and ubidecarenone (ubiquinone), otherwise known as coenzyme Q(10) (CoQ(10)). Recent interest has focused on the possible role CoQ(10) deficiency may have in the pathophysiology of the rare adverse effects of statin treatment. Currently, there is insufficient evidence from human studies to link statin therapy unequivocally to pathologically significantly decreased tissue CoQ(10) levels. Although statin treatment has been reported to lower plasma/serum CoQ(10) status, few human studies have assessed tissue CoQ(10) status. The plasma/serum CoQ(10) level is influenced by a number of physiological factors and, therefore, has limited value as a means of assessing intracellular CoQ(10) status. In those limited studies that have assessed the effect of statin treatment upon tissue CoQ(10) levels, none have shown evidence of a fall in CoQ(10) levels. This may reflect the doses of statins used, since many appear to have been used at doses below those recommended for their maximum therapeutic effects. Moreover, the poor bioavailability in those peripheral tissues tested may not reflect the effects the agents are having in liver and muscle, the tissues commonly affected in those patients who do not tolerate statins. This article reviews the biochemistry of CoQ(10), its role in cellular metabolism and the available evidence linking possible CoQ(10) deficiency to statin therapy.

Prevalence of Potentially Severe Drug-Drug Interactions in Ambulatory Patients with Dyslipidaemia Receiving HMG-CoA Reductase Inhibitor Therapy

BACKGROUND

Drug-drug interactions (DDIs) are a well known risk factor for adverse drug reactions. HMG-CoA reductase inhibitors ('statins') are a cornerstone in the treatment of dyslipidaemia and patients with dyslipidaemia are concomitantly treated with a variety of additional drugs. Since DDIs are associated with adverse reactions, we performed a cross-sectional study to assess the prevalence of potentially critical drug-drug and drug-statin interactions in an outpatient adult population with dyslipidaemia.

METHODS

Data from patients with dyslipidaemia treated with a statin were collected from 242 practitioners from different parts of Switzerland. The medication list was screened for potentially harmful DDIs with statins or other drugs using an interactive electronic drug interaction program.

RESULTS

We included 2742 ambulatory statin-treated patients (mean age +/- SD 65.1 +/- 11.1 years; 61.6% males) with (mean +/- SD) 3.2 +/- 1.6 diagnoses and 4.9 +/- 2.4 drugs prescribed. Of those, 190 patients (6.9%) had a total of 198 potentially harmful drug-statin interactions. Interacting drugs were fibrates or nicotinic acid (9.5% of patients with drug-statin interactions), cytochrome P450 (CYP) 3A4 inhibitors (70.5%), digoxin (22.6%) or ciclosporin (cyclosporine) [1.6%]. The proportion of patients with a potential drug-statin interaction was 12.1% for simvastatin, 10.0% for atorvastatin, 3.8% for fluvastatin and 0.3% for pravastatin. Additionally, the program identified 393 potentially critical non-statin DDIs in 288 patients.

CONCLUSIONS

CYP3A4 inhibitors are the most frequent cause of potential drug interactions with statins. As the risk for developing rhabdomyolysis is increased in patients with drug-statin interactions, clinicians should be aware of the most frequently observed drug-statin interactions and how these interactions can be avoided.

Blocking the Raf/MEK/ERK pathway sensitizes acute myelogenous leukemia cells to lovastatin-induced apoptosis

The statin family of drugs are well-established inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase and are used clinically in the control of hypercholesterolemia. Recent evidence, from ourselves and others, shows that statins can also trigger tumor-specific apoptosis by blocking protein geranylgeranylation. We and others have proposed that statins disrupt localization and function of geranylgeranylated proteins responsible for activating signal transduction pathways essential for the growth and/or survival of transformed cells. To explore this further, we have investigated whether the mitogen-activated protein kinase (MAPK) signaling cascades play a role in regulating statin-induced apoptosis. Cells derived from acute myelogenous leukemia (AML) are used as our model system. We show that p38 and c-Jun NH2-terminal kinase/stress-activated kinase MAPK pathways are not altered during lovastatin-induced apoptosis. By contrast, exposure of primary and established AML cells to statins results in significant disruption of basal extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. Addition of geranylgeranyl PPi reverses statin-induced loss of ERK1/2 phosphorylation and apoptosis. By establishing and evaluating the inducible Raf-1:ER system in AML cells, we show that constitutive activation of the Raf/MAPK kinase (MEK)/ERK pathway significantly represses but does not completely block lovastatin-induced apoptosis. Our results strongly suggest statins trigger apoptosis by regulating several signaling pathways, including the Raf/MEK/ERK pathway. Indeed, down-regulation of the Raf/MEK/ERK pathway potentiates statin-induced apoptosis because exposure to the MEK1 inhibitor PD98059 sensitizes AML cells to low, physiologically achievable concentrations of lovastatin. Our study suggests that lovastatin, alone or in combination with a MEK1 inhibitor, may represent a new and immediately available therapeutic approach to combat tumors with activated ERK1/2, such as AML.

Fluvastatin and fluvastatin extended release: a clinical and safety profile

Cardiovascular diseases due to atherosclerosis are the leading causes of mortality in the Western world. Cholesterol-lowering therapy with 3-hydroxy-3-methylglutaryl coenzyme Areductase inhibitors (statins) has demonstrated a reduction in cardiovascular morbidity and mortality in diverse populations. Fluvastatin (Lescol, Novartis Pharmaceuticals) was the first totally synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor on the market and has recently become available in an extended-release formulation (Lescol XL, Novartis Pharmaceuticals). Data from several clinical outcome trials have shown substantial benefits from fluvastatin treatment in diverse populations. Fluvastatin exists primarily in its acid form and as inactive metabolites in vivo, while active metabolites as well as the lactone form are only present in small amounts. The demonstration of the safe use of fluvastatin in a wide range of patients may be associated with the predominant acid form of the drug in vivo, as well as its predominant metabolism via the cytochrome P450 2C9 pathway.

The Potential Role of HMG-CoA Reductase Inhibitors in Pediatric Nephrotic Syndrome

OBJECTIVE

To evaluate the safety and efficacy of the hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) as a potential treatment option for the dyslipidemia associated with childhood nephrotic syndrome.

DATA SOURCES

Searches of MEDLINE (1966–April 2004), Cochrane Library, International Pharmaceutical Abstracts (1977–April 2004), and an extensive manual review of journals were performed using the key search terms nephrotic syndrome, familial hypercholesterolemia, dyslipidemia, and HMG-CoA reductase inhibitor.

STUDY SELECTION AND DATA EXTRACTION

Two prospective uncontrolled studies evaluating the safety and efficacy of statin therapy in pediatric nephrotic syndrome were included.

DATA SYNTHESIS

While an extensive amount of data is available in adult nephrotic syndrome in which statin therapy decreases total plasma cholesterol 22–39%, low-density lipoprotein cholesterol (LDL-C) 27–47%, and total plasma triglycerides 13–38%, only 2 small uncontrolled studies have been conducted evaluating the utility of these agents in pediatric nephrotic syndrome. These studies indicate that statins are capable of safely reducing total cholesterol up to 42%, LDL-C up to 46%, and triglyceride levels up to 44%.

CONCLUSIONS

Lowering cholesterol levels during childhood may reduce the risk for atherosclerotic changes and may thus be of benefit in certain patients with nephrotic syndrome. Statins have demonstrated short-term safety and efficacy in the pediatric nephrotic syndrome population. Implementing pharmacologic therapy with statins in children with nephrotic syndrome must be done with care until controlled studies are conducted in this population.

Safety of statins: focus on clinical pharmacokinetics and drug interactions

Statin monotherapy is generally well tolerated, with a low frequency of adverse events. The most important adverse effects associated with statins are myopathy and an asymptomatic increase in hepatic transaminases, both of which occur infrequently. Because statins are prescribed on a long-term basis, however, possible interactions with other drugs deserve particular attention, as many patients will typically receive pharmacological therapy for concomitant conditions during the course of statin treatment. This review summarizes the pharmacokinetic properties of statins and emphasizes their clinically relevant drug interactions.

Safety of rosuvastatin

The safety and tolerability of rosuvastatin were assessed (as of August 2003) using data from 12,400 patients who received 5 to 40 mg of rosuvastatin in a multinational phase II/III program, which represented 12,212 patient-years of continuous exposure to rosuvastatin. An integrated database was used to examine adverse events and laboratory data. In placebo-controlled trials, adverse events, irrespective of causality assessment, occurred in 57.4% of patients who received 5 to 40 mg of rosuvastatin (n = 744) and 56.8% of patients who received placebo (n = 382). In fixed-dose trials with comparator statins, 5 to 40 mg of rosuvastatin showed an adverse event profile similar to those for 10 to 80 mg of atorvastatin, 10 to 80 mg of simvastatin, and 10 to 40 mg of pravastatin. Clinically significant elevations in alanine aminotransferase (>3 times the upper limit of normal) and creatine kinase (>10 times the upper limit of normal) were uncommon (<or=0.2%) in the groups that received rosuvastatin and comparator statins. Myopathy (creatine kinase >10 times the upper limit of normal with muscle symptoms) that was possibly related to treatment occurred in <or=0.03% of patients who took rosuvastatin at doses <or=40 mg. A positive finding of proteinuria with dipstick testing at rosuvastatin doses <or=40 mg was comparable to that seen with other statins, and the development of proteinuria was not predictive of acute or progressive renal disease. No deaths in the program were attributed to rosuvastatin, and no rhabdomyolysis occurred in patients who received 5 to 40 mg of rosuvastatin. Rosuvastatin was well tolerated by a broad range of patients who had dyslipidemia, and its safety profile was similar to those of the comparator statins investigated in this extensive clinical program.

Efficacy and safety of ezetimibe coadministered with statins: randomised, placebo-controlled, blinded experience in 2382 patients with primary hypercholesterolemia

We assessed pooled safety and lipid-regulating efficacy data from four similarly designed trials of ezetimibe coadministered with statins in 2382 patients with primary hypercholesterolemia. Patients were randomised to one of the following double-blind treatments for 12 weeks: placebo; ezetimibe 10 mg; statin; or statin + ezetimibe. Statin doses tested were 10, 20, 40 mg/day (atorvastatin, simvastatin, pravastatin or lovastatin) or 80 mg/day (atorvastatin, simvastatin). Treatment with ezetimibe + statin led to significantly greater reductions in low-density lipoprotein cholesterol (LDL-C), total cholesterol, triglycerides, non-high-density lipoprotein cholesterol (non-HDL-C), apolipoprotein B and increases in HDL-C, compared to statin alone. At each statin dose, treatment with ezetimibe + statin led to a greater LDL-C reduction compared to the next highest statin monotherapy dose. Ezetimibe + statin had a safety profile similar to statin monotherapy. Coadministration of ezetimibe + statin offers a well-tolerated, highly efficacious new treatment strategy for patients with hypercholesterolemia.

Liver function test abnormalities and pruritus in a patient treated with atorvastatin: case report and review of the literature

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (also known as statins) are associated with elevated transaminase levels in 1-3% of patients. Therapy with these drugs requires monitoring of alanine aminotransferase (ALT) levels because animal studies and premarketing clinical trials showed signs of hepatotoxicity that were primarily minor elevations of ALT. Nevertheless, postmarketing experience suggests that hepatotoxicity is rare, and that elevated ALT levels are reversible with continued therapy and probably are related to cholesterol lowering. Based on the low occurrence of ALT elevations and the lack of clinical evidence of hepatotoxicity, some clinicians are calling for a change in the current practice of monitoring liver function tests. We report, however, the case of a 71-year-old woman who was receiving atorvastatin and experienced elevated transaminase levels on two occasions, and developed pruritus on rechallenge with the drug. Thus, clinicians should be aware of asymptomatic elevations in liver function tests in patients receiving atorvastatin who do not have known risk factors for liver damage.

Combination lipid-lowering therapy with statins: safety issues in the postcerivastatin era

Combination lipid-altering regimens represent an emerging clinical paradigm to meet increasingly stringent consensus lipoprotein targets for coronary prevention. This practice, together with escalating prevalences of coronary artery disease in certain ageing (western industrial) populations, polypharmacy in the elderly and the recent voluntary market withdrawal of cerivastatin, warrants a re-examination of the safety profiles of 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors (i.e., statins). These agents are exceedingly well-tolerated in the vast majority of patients, very infrequently precipitating musculoskeletal symptoms and/or signs. Statins vary in their pharmacological profiles, leading to distinct levels of systemic exposure and capacities to penetrate skeletal myocytes. Pharmacokinetic interactions with certain agents increase the likelihood of statin-induced myopathy and, in exceedingly rare instances, potentially fatal rhabdomyolysis with myoglobinuria and renal failure. As with other medical decisions, the anticipated benefits of long-term statin therapy, with or without other lipid-altering agents, need to be weighed against the prospects of clinically significant drug interactions. In clinical trials and postmarketing surveillance, the two statins that are not metabolised by the cytochrome P450 3A4 system (fluvastatin and pravastatin) have exhibited very low propensities to elicit myopathy when combined with other agents. These agents should be considered initially when contemplating combination lipid-lowering regimens for coronary prevention.

Clinical effects of rosuvastatin, a new HMG-CoA reductase inhibitor, in Japanese patients with primary hypercholesterolemia: an early phase II study

The effects and tolerability of the new HMG-CoA reductase inhibitor rosuvastatin were assessed in 68 hypercholesterolemic Japanese patients (22 men and 46 postmenopausal women; age range 28-72 years) in a multicenter, double-blind, dose-ranging, early phase II study. Patients were randomized into three groups and received once-daily doses of 1, 2, or 4 mg rosuvastatin. Sixty evaluable patients (19 men and 41 women) with mean total cholesterol (TC) 294 mg/dl (7.60 mmol/l) and mean triglyceride (TG) 150 mg/dl (1.69 mmol/l) provided data in the efficacy analysis based on percentage changes in lipids at 4 and 8 weeks. All doses of rosuvastatin improved lipid parameters after both 4 and 8 weeks of therapy. On average, TC decreases were 22-29%, low-density lipoprotein cholesterol (LDL-C) decreases 32-42%, TG decreases 2% to 22%, and HDL-C increases 3-7%. There were no remarkable differences between efficacy at 4 and at 8 weeks, and dose-dependent reductions were noted for LDL-C, with 30, 39, and 42% decreases in the 1-, 2-, and 4-mg/ day dose groups, respectively, at 8 weeks. The drug was well tolerated over the 8 weeks of therapy. These preliminary results indicate that rosuvastatin is a potent cholesterol-lowering agent, capable of achieving marked reductions in LDL-C even at low doses.

Statins and myotoxicity

The significant age-adjusted decline in cardiovascular mortality that has occurred over the past three decades is multifactorial. However, the advent of statin therapy has markedly facilitated the optimization of dyslipidemia in patients at risk for coronary events. Statin therapy has proven to be effective in reducing morbidity and mortality in large-scale primary and secondary prevention trials. As with all therapies, the administration of 3-hydroxy-3-methylglutaryl coenzyme A (HMG Co A) reductase inhibitors is not without clinical risks. Myopathy, albeit uncommon, was one of the earliest clinical problems associated with statin therapy. Recent data from the large-scale statin mega-trials have clarified the quantitative clinical risk-benefit relationship of reductase inhibitors relative to the induction of muscle toxicity. Histopathologic studies have clarified the potential role of statins in the syndrome of myalgias and normal creatine kinase levels. However, the precise mechanism of statin-associated muscle toxicity remains unclear and is potentially related to genetically mediated muscle enzyme defects, drug interactions, intracellular depletion of metabolic intermediates, and intrinsic properties of the statins per se.

Treatment of patients with lipid disorders in the primary care setting: new treatment guidelines and their implications

Coronary heart disease (CHD) remains a major cause of morbidity and mortality throughout North America. The role played by lipid abnormalities is now well established, and primary care physicians can play a major role in reversing the increasing prevalence of CHD by following the recommended guidelines of the National Cholesterol Expert Panel (NCEP ATP-III). While many physicians are aware of the importance of lowering lipid levels, a large number of patients still fail to reach their treatment goals. It is therefore important to identify patients at risk of developing coronary events due to abnormal lipid profiles and to quickly implement effective prevention programs. Although diet and other lifestyle modifications should form the basis of lipid management, the addition of lipid-modifying drugs is often necessary. Several lipid-modifying agents are available, but the proven efficacy and good tolerability of statins has increasingly made them the drugs of choice.

Ezetimibe coadministered with simvastatin in patients with primary hypercholesterolemia

OBJECTIVES

The purpose of this study was to assess the efficacy and safety of ezetimibe administered with simvastatin in patients with primary hypercholesterolemia.

BACKGROUND

Despite the availability of statins, many patients do not achieve lipid targets. Combination therapy with lipid-lowering agents that act via a complementary pathway may allow additional patients to achieve recommended cholesterol goals.

METHODS

After dietary stabilization, a 2- to 12-week washout period, and a 4-week, single-blind, placebo lead-in period, patients with baseline low-density lipoprotein cholesterol (LDL-C) > or =145 mg/dl to < or =250 mg/dl and triglycerides (TG) < or =350 mg/dl were randomized to one of the following 10 groups administered daily for 12 consecutive weeks: ezetimibe 10 mg; simvastatin 10, 20, 40, or 80 mg; ezetimibe 10 mg plus simvastatin 10, 20, 40, or 80 mg; or placebo. The primary efficacy variable was percentage reduction from baseline to end point in direct LDL-C for the pooled ezetimibe plus simvastatin groups versus pooled simvastatin groups.

RESULTS

Ezetimibe plus simvastatin significantly improved LDL-C (p < 0.01), high-density lipoprotein cholesterol (HDL-C) (p = 0.03), and TG (p < 0.01) compared with simvastatin alone. Ezetimibe plus simvastatin (pooled doses) provided an incremental 13.8% LDL-C reduction, 2.4% HDL-C increase, and 7.5% TG reduction compared with pooled simvastatin alone. Coadministration of ezetimibe and simvastatin provided LDL-C reductions of 44% to 57%, TG reductions of 20% to 28%, and HDL-C increases of 8% to 11%, depending on the simvastatin dose. Ezetimibe 10 mg plus simvastatin 10 mg and simvastatin 80 mg alone each provided a 44% LDL-C reduction. The coadministration of ezetimibe with simvastatin was well tolerated, with a safety profile similar to those of simvastatin and of placebo.

CONCLUSIONS

When coadministered with simvastatin, ezetimibe provided significant incremental reductions in LDL-C and TG, as well as increases in HDL-C. Coadministration of ezetimibe with simvastatin was well tolerated and comparable to statin alone.

Safety considerations for statins

PURPOSE OF REVIEW

The hydroxymethyl glutaryl coenzyme A reductase inhibitors or statins offer important benefits for the large populations of individuals at high risk for coronary heart disease. These drugs have a good safety profile. Nevertheless, differences in physicochemical and pharmacokinetic properties between statins may translate into significant differences in long-term safety. This review focuses on long-term adverse effects related to statin use, namely hepatotoxicity and myopathy. Moreover, the most common drugs used in combination with statins in long-term therapies are analyzed in terms of possible drug/drug interactions affecting the safety of statins.

RECENT FINDINGS

The withdrawal of cerivastatin from the global market in 2001, because of severe cases of rhabdomyolysis, highlighted concerns regarding the safety of the entire class. Afterwards, the role of statins and their interactions with other drugs in precipitating this condition have been carefully reviewed. In approximately 60% of the total number of cases, statin-related rhabdomyolysis was found to be related to drug/drug interactions. Recently, all cases of fatal rhabdomyolysis associated with statin use have been reported to the US Food and Drug Administration. This has shown that fatal rhabdomyolysis among statin users is a rare event, the reporting rates being much less than one death per million prescriptions in the case of all statins except cerivastatin.

SUMMARY

The safety and tolerability of the available statins support their use as the first-line treatment of patients at high risk for coronary heart disease, since the clinical benefits greatly outweigh the small risk of myopathy. Nevertheless, clinicians should be aware of the adverse effects possibly related to statin therapy, particularly in patients at high risk for coronary heart disease and requiring long-term multiple-drug therapies.

Regulation of CYP2B6 and CYP3A expression by hydroxymethylglutaryl coenzyme A inhibitors in primary cultured human hepatocytes

The effects of treatment with the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) inhibitors lovastatin, simvastatin, pravastatin, fluvastatin, and atorvastatin on the contents of cytochrome p450 mRNAs were examined in primary cultures of human hepatocytes prepared from three different livers. Treatment of 2- to 3-day-old human hepatocyte cultures with 3 x 10(-5) M lovastatin, simvastatin, fluvastatin, or atorvastatin for 24 h increased the amounts of CYP2B6 and CYP3A mRNA by an average of 3.8- to 9.2-fold and 24- to 36-fold, respectively. In contrast, pravastatin treatment had no effect on the mRNA level of either CYP2B6 or CYP3A, although treatment with pravastatin did produce the expected compensatory increase in HMG-CoA reductase mRNA content, indicating effective inhibition of cholesterol biosynthesis. Although treatment with the active (+), but not the inactive (-), enantiomer of atorvastatin increased the amount of HMG-CoA reductase mRNA, treatment with each enantiomer significantly induced both CYP2B6 and CYP3A mRNA levels. Treatment of primary cultured rat hepatocytes with the atorvastatin enantiomers effectively increased the amount of CYP3A mRNA, but had no effect on CYP2B or CYP4A mRNA levels, in contrast to fluvastatin, which increased both. Findings for p450 proteins by Western blotting were consistent with the mRNA results. These findings indicate that the ability of a drug to inhibit HMG-CoA reductase activity does not predict its ability to produce p450 induction in primary cultured human hepatocytes, and demonstrate that some, but not all, of the effects of these drugs that occur in primary cultured rat hepatocytes are conserved in human hepatocyte cultures.

Simvastatin treatment in the SLO syndrome: a safe approach?

Soon after the discovery of reduced cholesterol synthesis in the Smith-Lemli-Opitz syndrome (SLOS), several trials with dietary supplementation were initiated with the aim of increasing cholesterol and reducing the de novo synthesis and accumulation of 7- and 8-dehydrocholesterol (DHC). Dietary cholesterol raises cholesterol levels in the circulation with only marginal effects on levels of DHC. Photosensitivity and polyneuropathy have been reported to be improved by the treatment, but other effects have been difficult to evaluate. In order to see whether inhibition of hydroxymethylglutaryl CoA reductase is of benefit, two of our patients have been treated with simvastatin in addition to the long-term treatment with cholesterol and bile acids. Absolute as well as relative levels of DHC were reduced. In one patient, creatine kinase increased moderately after 2 months of treatment. In the other patient, the treatment had to be interrupted because of hepatotoxic side effects with a marked increase in alanine aminotransferase and aggravation of the hypocholesterolemia and photosensitivity. We conclude that even if the levels of accumulated intermediates can be reduced, treatment with a statin may be harmful in some patients with SLOS.

Acute rhabdomyolysis after cardiac transplantation: a diagnostic conundrum

A 13-year-old girl presented with right ventricular failure secondary to Ebstein's malformation (downward displacement of the tricuspid valve leaflets with adherence to the right ventricular muscle and redundancy or dysplasia of the tricuspid valve leaflets). She subsequently required a heart transplant but developed rhabdomyolysis early in the postoperative period and required ventilatory support for more than 3 weeks. A variety of causes were considered, but her condition improved only when cyclosporin was eliminated from the immunosuppression regimen. We believe it is likely that the rhabdomyolysis has been caused by cyclosporin. If so, this has occurred both earlier in the clinical course and at lower serum concentrations than previously described.

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.

The myotoxicity of statins

PURPOSE OF REVIEW

Since hypercholesterolaemia is a chronic condition, the long-term safety of statins is important. Adverse reactions involving skeletal muscle are the most common (reported incidence 1-7%). The recent withdrawal of cerivastatin because of deaths from rhabdomyolysis, of which 25% were related to gemfibrozil-cerivastatin combination therapy, has focused attention on myotoxicity associated with statins and in particular with statin-fibrate combinations. We review the safety profiles of the individual statins, and discuss the mechanisms that may account for myotoxicity associated with statins and these agents and how these may relate to the different myotoxic potential of individual agents.

RECENT FINDINGS

The statins, particularly the first-generation agents, have been well evaluated from the perspective of safety and efficacy. Cerivastatin was associated with a 10-fold higher incidence of myotoxicity than any other statin, suggesting that there may be differences in myotoxic potential between agents. Statin-associated myotoxicity is complex, involving effects on cell membrane structure and function, mitochondrial dysfunction and impaired myocyte duplication. Potential differences in myotoxicity between agents may relate to the physicochemical, pharmacokinetic and pharmacodynamic properties of individual drugs. The aetiology of myotoxicity associated with statin-fibrate combination therapy is complex and multifactorial, with recent studies suggesting that there may be differences in myotoxic potential between individual fibrates.

SUMMARY

Recent evidence suggests that there may be differences in myotoxic potential between individual agents. Thus, the choice of hypolipidaemic therapy needs to be based not only on outcome evidence and cost-effectiveness analysis, but also on safety considerations for individual agents.

The rational use of potentially hepatotoxic medications in patients with underlying liver disease

Given the fact that as many as 9% of all adverse drug reactions involve toxic effects on the liver and with upwards of 50% of all cases of fulminant hepatic failure being ascribed to acetaminophen and other agents, the safe use of medications takes on an even greater importance whenever the prescription of potentially hepatotoxic drugs to patients with underlying liver disease is considered. In general, it is thought that most drugs can be safely administered in the setting of liver disease without an increased risk of hepatotoxicity, although the evidence on which this statement is based often relies more on clinical judgement than on clinical studies. Several drugs appear to have an increased risk of hepatotoxicity in patients with underlying liver disease based on either clinical reports or extrapolated pharmacological data. These agents, including methotrexate, niacin and the antiretroviral and antituberculosis drugs, carry warnings about their use in patients with a variety of liver conditions. The data supporting the hepatotoxic risk of scores of additional drugs, such as the 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors ("statins"), the newer thiazolidinediones (rosiglitazone, pioglitazone), and tamoxifen, among others, in patients with liver disease are generally lacking by evidence-based studies. However, clinical and biochemical monitoring is routinely recommended or required, often to make up for the lack of information on the true risk of clinically significant liver toxicity of these agents in individuals both with and without underlying liver disease. This article will review what is and what is not known about prescribing in the setting of acute and chronic liver disease and offers recommendations to help promote the safe and rational use of potentially hepatotoxic medications in these patients.