Severe hepatic side effects of ezetimibe

Protective mechanisms of a microbial oil against hypercholesterolemia: evidence from a zebrafish model

A Western diet elevates the circulating lipoprotein and triglyceride levels which are the major risk factors in cardiovascular disease (CVD) development. Consumption of long-chain omega-3 fatty acids can stall the disease progression. Although these fatty acids can significantly impact the intestine under a hypercholesterolemic condition, the associated changes have not been studied in detail. Therefore, we investigated the alterations in the intestinal transcriptome along with the deviations in the plasma lipids and liver histomorphology of zebrafish offered DHA- and EPA-rich oil. Fish were allocated to 4 dietary treatments: a control group, a high cholesterol group and microbial oil groups with low (3.3%) and high (6.6%) inclusion levels. We quantified the total cholesterol, lipoprotein and triglyceride levels in the plasma. In addition, we assessed the liver histology, intestinal transcriptome and plasma lipidomic profiles of the study groups. The results suggested that higher levels of dietary microbial oil could control the CVD risk factor indices in zebrafish plasma. Furthermore, microbial oil-fed fish had fewer liver vacuoles and higher mRNA levels of genes involved in β-oxidation and HDL maturation. Analyses of the intestine transcriptome revealed that microbial oil supplementation could influence the expression of genes altered by a hypercholesterolemic diet. The plasma lipidomic profiles revealed that the higher level of microbial oil tested could elevate the long-chain poly-unsaturated fatty acid content of triglyceride species and lower the concentration of several lysophosphatidylcholine and diacylglycerol molecules. Our study provides insights into the effectiveness of microbial oil against dyslipidemia in zebrafish.

Identification of a Chromosome 1 Substitution Line B6-Chr1BLD as a Novel Hyperlipidemia Model via Phenotyping Screening

Hyperlipidemia is a chronic disease that seriously affects human health. Due to the fact that traditional animal models cannot fully mimic hyperlipidemia in humans, new animal models are urgently needed for basic drug research on hyperlipidemia. Previous studies have demonstrated that the genomic diversity of the wild mice chromosome 1 substitution lines was significantly different from that of laboratory mice, suggesting that it might be accompanied by phenotypic diversity. We first screened the blood lipid-related phenotype of chromosome 1 substitution lines. We found that the male HFD-fed B6-Chr1BLD mice showed more severe hyperlipidemia-related phenotypes in body weight, lipid metabolism and liver lesions. By RNA sequencing and whole-genome sequencing results of B6-Chr1BLD, we found that several differentially expressed single nucleotide polymorphism enriched genes were associated with lipid metabolism-related pathways. Lipid metabolism-related genes, mainly including Aida, Soat1, Scly and Ildr2, might play an initial and upstream role in the abnormal metabolic phenotype of male B6-Chr1BLD mice. Taken together, male B6-Chr1BLD mice could serve as a novel, polygenic interaction-based hyperlipidemia model. This study could provide a novel animal model for accurate clinical diagnosis and precise medicine of hyperlipidemia.

Nanoformulation of Seaweed Eisenia bicyclis in Albumin Nanoparticles Targeting Cardiovascular Diseases: In Vitro and In Vivo Evaluation

Natural products, especially those derived from seaweeds, are starting to be seen as effective against various diseases, such as cardiovascular diseases (CVDs). This study aimed to design a novel oral formulation of bovine albumin serum nanoparticles (BSA NPs) loaded with an extract of Eisenia bicyclis and to validate its beneficial health effects, particularly targeting hypercholesterolemia and CVD prevention. Small and well-defined BSA NPs loaded with Eisenia bicyclis extract were successfully prepared exhibiting high encapsulation efficiency. Antioxidant activity and cholesterol biosynthesis enzyme 3-hydroxy-3 methylutaryl coenzyme A reductase (HMGR) inhibition, as well as reduction of cholesterol permeation in intestinal lining model cells, were assessed for the extract both in free and nanoformulated forms. The nanoformulation was more efficient than the free extract, particularly in terms of HMGR inhibition and cholesterol permeation reduction. In vitro cytotoxicity and in vivo assays in Wistar rats were performed to evaluate its safety and overall effects on metabolism. The results demonstrated that the Eisenia bicyclis extract and BSA NPs were not cytotoxic against human intestinal Caco-2 and liver HepG2 cells and were also safe after oral administration in the rat model. In addition, an innovative approach was adopted to compare the metabolomic profile of the serum from the animals involved in the in vivo assay, which showed the extract and nanoformulation's impact on CVD-associated key metabolites. Altogether, these preliminary results revealed that the seaweed extract and the nanoformulation may constitute an alternative natural dosage form which is safe and simple to produce, capable of reducing cholesterol levels, and consequently helpful in preventing hypercholesterolemia, the main risk factor of CVDs.

Lipid-Lowering Therapy in Woman of Childbearing Age: a Review and Stepwise Clinical Approach

PURPOSE OF REVIEW

Women are less often recognized to have cardiovascular disease (CVD) risk and are underrepresented in randomized trials of lipid-lowering therapy. Here, we summarize non-pharmacologic and pharmacologic strategies for lipid-lowering in women of childbearing age, lipid changes during pregnancy and lactation, discuss sex-specific outcomes in currently available literature, and discuss future areas of research.

RECENT FINDINGS

While lifestyle interventions form the backbone of CVD prevention, some women of reproductive age have an indication for pharmacologic lipid-lowering. Sex-based evidence is limited but suggests that both statin and non-statin lipid-lowering agents are beneficial regardless of sex, especially at high cardiovascular risk. Pharmacologic lipid-lowering therapies, both during the pregnancy period and during lactation, have historically been and continue to be limited by safety concerns. This oftentimes limits lipid-lowering options in women of childbearing age. In this review, we summarize lipid-lowering strategies in women of childbearing age and the impact of therapies during pregnancy and lactation. The limited sex-specific data regarding efficacy, adverse events, and cardiovascular outcomes underscore the need for a greater representation of women in randomized controlled trials. More data on lipid-lowering teratogenicity are needed, and through increased clinician awareness and reporting to incidental exposure registries, more data can be harvested.

Modifying pH-sensitive PCSK9/LDLR interactions as a strategy to enhance hepatic cell uptake of low-density lipoprotein cholesterol (LDL-C)

LDL-receptor (LDLR)-mediated uptake of LDL-C into hepatocytes is impaired by lysosomal degradation of LDLR, which is promoted by proprotein convertase subtilisin/kexin type 9 (PCSK9). Cell surface binding of PCSK9 to LDLR produces a complex that translocates to an endosome, where the acidic pH strengthens the binding affinity of PCSK9 to LDLR, preventing LDLR recycling to the cell membrane. We present a new approach to inhibit PCSK9-mediated LDLR degradation, namely, targeting the PCSK9/LDLR interface with a PCSK9-antagonist, designated Flag-PCSK9PH, which prevents access of WT PCSK9 to LDLR. In HepG2 cells, Flag-PCSK9PH, a truncated version (residues 53–451) of human WT PCSK9, strongly bound LDLR at the neutral pH of the cell surface but dissociated from it in the endosome (acidic pH), allowing LDLR to exit the lysosomes intact and recycle to the cell membrane. Flag-PCSK9PH thus significantly enhanced cell-surface LDLR levels and the ability of LDLR to take up extracellular LDL-C.

Liver Injury Associated With Ezetimibe Monotherapy

Statin intolerance, primarily myalgia, is not uncommon in patients treated for elevated low-density lipoprotein cholesterol. Nonstatin drugs, such as ezetimibe, can spare patients from statin exposure, while still reducing low-density lipoprotein cholesterol. Ezetimibe is generally very well tolerated, although gastrointestinal and musculoskeletal symptoms have been occasionally reported. We describe an extremely rare case of an ezetimibe-associated liver injury who required protracted treatment with prednisone and azathioprine. Ezetimibe-associated liver injury should be suspected with development of hepatic abnormalities concurrent with the timing of ezetimibe treatment and in the absence of other possible precipitating factors.

Effects of earthworm extract on the lipid profile and fatty liver induced by a high-fat diet in guinea pigs

Background

Non-alcoholic fatty liver disease (NAFLD), characterized by the accumulation of excess fat in the liver in people who consume little or no alcohol, is becoming increasingly common around the world, especially in developed countries. Extracts from earthworms have been used as alternative therapies for a variety of diseases but not in NAFLD. Therefore, the aim of this study was to investigate the effect of earthworm extract (EE) on diet-induced fatty liver disease in guinea pigs.

Methods

EE was extracted, and the effect of EE on the lipid levels and liver damage in guinea pigs fed a high-fat diet (HFD) was assessed. Thirty male guinea pigs at 3 weeks of age were allocated equally to five groups, namely, chow diet, HFD, and HFD with different dosages (0.3, 1.4 and 6.8 µg per kg bodyweight per day) of EE for 4 weeks, and their body weight was monitored throughout the experiment. Liver tissues were examined for gross morphology and histology. Serum levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), alanine transaminase (ALT) and aspartate aminotransferase (AST) were determined using an autoanalyser.

Results

HFD induced NAFLD in guinea pigs. HFD-fed guinea pigs that received EE treatment showed milder increases in the serum levels of TC, TG and LDL-C, as well as in the body weight growth rate, compared to the HFD group without EE supplementation. EE intervention reduced the number of lipid-containing hepatocytes, hepatocellular ballooning and sinusoidal distortion in the liver in HFD-fed animals. ALT in serum was significantly elevated by HFD. No statistically significant difference in ALT levels was found between the chow diet group and the HFD group with EE treatment.

Conclusions

This study demonstrates that the administration of EE suppressed the induction of serum TC, TG and LDL-C in response to HFD. EE also reduced liver damage in HFD-fed guinea pigs. These findings suggest that EE has alleviating effects on dyslipidaemia and liver damage associated with NAFLD.

Pharmacological Options in Atherosclerosis: A Review of the Existing Evidence

Coronary heart disease (CHD) is the leading cause of mortality worldwide and high low-density lipoprotein (LDL) cholesterol levels have been shown to be key in the pathogenesis of this condition. Lipid control has therefore been the subject of decades of research and has led to many large and robust randomized controlled trials, as well as the highest grossing drug of all time—Lipitor (atorvastatin). Statin therapy has long been indicated for secondary and more recently primary prevention. However, despite the large-scale use of statins, CHD prevalence remains high, and some patients do not respond to statin therapy. There has been a large push to find and test alternative lipid-lowering agents, these include fibrates, cholesterol absorption inhibitors, and proprotein convertase subtilisin/kexin type 9 (PCSK-9) inhibitors. It is the aim of this review to assess the literature surrounding each of these groups of drugs.

Dietary sphingolipids: potential for management of dyslipidemia and nonalcoholic fatty liver disease

The development of therapeutic approaches aimed at reducing inflammation, improving lipid metabolism, and preventing nonalcoholic fatty liver disease holds significant potential in the management of obesity-associated disease. In this review, the recent basic science and clinical research examining dietary sphingolipid intake and the prevention of dyslipidemia and nonalcoholic fatty liver disease is summarized. Dietary sphingolipids have been shown to dose-dependently reduce the acute intestinal absorption of cholesterol, triglycerides, and fatty acids in rodents. Overall, studies feeding dietary sphingolipids to rodents typically show reductions in serum lipids. Furthermore, these hypolipidemic effects are also observed in most human studies, although the magnitude of such effects is typically smaller. Dietary sphingolipids also appear useful in preventing hepatic lipid uptake and accumulation and have shown benefits in preventing hepatic steatosis in rodent models. Dietary sphingolipids may affect the gut-liver axis by preventing the translocation of gut bacteria-derived lipopolysaccharide and/or inhibiting its proinflammatory effects. Current evidence from preclinical studies indicates that dietary sphingolipids have lipid-lowering and anti-inflammatory properties, although their potential to prevent human chronic disease has not been fully explored. It will be important to determine if such effects seen in cell and animal models translate to humans. More research is warranted to define how dietary sphingolipids influence lipid metabolism and inflammation.

Recurrence and Severe Worsening of Hepatotoxicity After Reintroduction of Atorvastatin in Combination With Ezetimibe

Severe hepatotoxicity is a rare but well-known adverse reaction to statins. However, despite the widespread use of statins, only a few cases describing statin reexposure or switch to another statin after liver injury have been published. The literature on hepatotoxicity with ezetimibe alone or in combination with statins is also scarce. We report a case where a patient with a history of elevated liver enzymes while using atorvastatin, but prior and subsequent good tolerance to simvastatin and pravastatin, developed drug-induced liver injury on reexposure to a combination of atorvastatin and ezetimibe. The hepatotoxicity in our patient was most likely caused by reexposure to atorvastatin, although we cannot exclude ezetimibe as a contributing factor. This case highlights the risk of hepatotoxicity recurrence on rechallenge with the same statin. The tolerance to other statins in this case also strengthens the suspicion that statin-induced liver injury may not be a class effect, although the current data are too scarce to draw any definite conclusions.

Amelioration of non-alcoholic fatty liver disease with NPC1L1-targeted IgY or n-3 polyunsaturated fatty acids in mice

Patients with non-alcoholic fatty liver disease (NAFLD) have an increased risk for progression to hepatocellular carcinoma in addition to comorbidities such as cardiovascular and serious metabolic diseases; however, the current therapeutic options are limited. Based on our previous report that omega-3 polyunsaturated fatty acids (n-3 PUFAs) can significantly ameliorate high fat diet (HFD)-induced NAFLD, we explored the therapeutic efficacy of n-3 PUFAs and N-IgY, which is a chicken egg yolk-derived IgY specific for the Niemann-Pick C1-Like 1 (NPC1L1) cholesterol transporter, on NAFLD in mice. We generated N-IgY and confirmed its efficient cholesterol transport-blocking activity in HepG2 and Caco-2 cells, which was comparable to the effect of ezetimibe (EZM). C57BL/6 wild type and fat-1 transgenic mice, capable of producing n-3 PUFAs, were fed a high fat diet (HFD) alone or supplemented with N-IgY. Endogenously synthesized n-3 PUFAs combined with N-IgY led to significant decreases in hepatic steatosis, fibrosis, and inflammation (p<0.01). The combination of N-IgY and n-3 PUFAs resulted in significant upregulation of genes involved in cholesterol uptake (LDLR), reverse cholesterol transport (ABCG5/ABCG8), and bile acid metabolism (CYP7A1). Moreover, fat-1 transgenic mice treated with N-IgY showed significant downregulation of genes involved in cholesterol-induced hepatic stellate cell activation (Tgfb1, Tlr4, Col1a1, Col1a2, and Timp2). Collectively, these data suggest that n-3 PUFAs and N-IgY, alone or in combination, represent a promising treatment strategy to prevent HFD-induced fatty liver through the activation cholesterol catabolism to bile acids and by decreasing cholesterol-induced fibrosis.

Promotion of classic neutral bile acids synthesis pathway is responsible for cholesterol-lowing effect of Si-miao-yong-an decoction: Application of LC-MS/MS method to determine 6 major bile acids in rat liver and plasma

Si-miao-yong-an decoction (SMYAD), a traditional Chinese medicine formula, significantly reduced plasma TC, LDL-c levels and increased HDL-c level in hyperlipidemia rats. Liver function test and tissue section examination indicated that SMYAD improved liver function and reduced fat accumulation in hyperlipidemia rat liver. A LC-MS/MS method was established and well validated to evaluate major bile acids derived from cholesterol metabolism through the classic neutral pathway and the alternative acidic pathway (cholic acid, chenodeoxycholic acid and their taurine and glycine conjugates) in liver and plasma. Increased total 6 bile acids concentrations in both liver and plasma were observed after oral administration of 12g/kg/d, 24g/kg/d and 36g/kg/d of SMYAD in a dose dependent manner which contributed to eliminate of cholesterol. Cholic acid, taurocholic acid and glycocholic acid act as the main products of bile acid classic neutral synthesis pathway and show sharp increase (p<0.01) after treatment of SMYAD at dosage of 24-36g/kg/d. For liver samples, taurocholic acid level act as the largest growth section, while in plasma samples, cholic acid act as the largest growth section after SMYAD treatment, compared with Model group. By contrast, the main products of alternative acidic pathway (chenodeoxycholic acid and its glycine and taurine conjugates) show no significant increase after treatment of SMYAD. In conclusion, the cholesterol lowing effect of SMYAD may be related with the accelerated transformation of cholesterol into bile acids through the classic neutral pathway.

Spirogyra neglecta inhibits the absorption and synthesis of cholesterol in vitro

Background

Spirogyra neglecta (SN) has many nutritional benefits and it is commonly used to ameliorate different human conditions including inflammation, gastric ulcer, hyperglycemia, and hyperlipidemia. However, the mechanism of the hypocholesterolemic effect of SN still remains unclear. Therefore, the present study was aimed to evaluate the effect of SN extract particularly on cholesterol absorption and synthesis mechanisms.

Methods

For cholesterol absorption, the uptake of cholesterol was measured by using tritium radiolabeling of cholesterol in Caco-2 cells. Bile acid binding, micelles size, and cholesterol solubility were analyzed in in vitro assays, while cholesterol synthesis was evaluated by using a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase assay kit.

Results

SN extract was found to decrease cholesterol uptake in Caco-2 cells and decreased the solubility of cholesterol in micelles. The SN extract bound to taurocholate, taurodeoxycholate, and glycodeoxycholate bile acids, and increased micelles size. SN has also demonstrated an inhibitory effect on HMG-CoA reductase (HMGR) enzymatic activity. For further experimentation, the treatment combination of SN and ezetimibe (0.04 mg/mL) showed a greater significant reduction in cholesterol uptake than the extract alone.

Conclusion

These observations suggested that inhibitory cholesterol absorption effects of SN could be mediated through the modulation of size and solubility of cholesterol micelles, resulting in interference of cholesterol uptake. In addition, SN inhibited the rate limiting step of cholesterol synthesis. This study provides supporting evidence for the potential usage of SN as a cholesterol lowering agent.

The safety of ezetimibe and simvastatin combination for the treatment of hypercholesterolemia

INTRODUCTION

In the light of the most recent and stricter dyslipidemia treatment guidelines, the need for combination hypolipidemic therapy is increasing. Ezetimibe plus simvastatin is available as a fixed dose therapy offering an efficient hypolipidemic treatment choice. Based on the positive results of the IMProved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT) trial, the use of this drug combination is expected to increase in the next years.

AREAS COVERED

This review discusses the current evidence regarding the safety of ezetimibe/simvastatin combination. Current evidence regarding possible associated side effects (musculoskeletal, gastrointestinal, endocrine, hematological, renal, ophthalmologic, allergic, malignancy) and drug interactions of this combination is thoroughly discussed.

EXPERT OPINION

Ezetimibe and simvastatin treatment, either as a single pill or the combined use of the individual compounds, offers limited additional risk compared with simvastatin monotherapy and comprises a safe and efficient choice for dyslipidemia treatment in high-risk and diabetic patients.

Lipid-lowering agents-induced autoimmune hepatitis: A systematic review

AIM: To identify the clinical characteristics of lipid-lowering agents-induced autoimmune hepatitis (AIH).

METHODS: The clinical data for patients with lipid-lowering agents-induced AIH were retrieved from Chinese Biomedical Database, VIP Medical information resource system and PubMed (January 1983 to October 2014) to conduct a systematic review.

RESULTS: Multiple lipid-lowering agents could induce AIH. A total of 14 cases due to 7 kinds of drugs were identified, and 64.3% (9/14) of the patients were females. No significant differences were found in clinical manifestations or liver histology compared to sporadic AIH, and lipid-lowering agents-induced AIH patients might have extrahepatic manifestations such as systemic lupus erythematosus and rhabdomyolysis. Different statins might have cross-toxicity, liver injury with a shorter latency period and more serious symptoms could occur when other statins were reused. Discontinuation of offending drugs was the essential treatment when the diagnosis was established; however, liver function in 6 patients was even worse although the drugs were stopped and 28.6% (4/14) of the patients finally developed cirrhosis. Immunosuppressive therapy was needed in 92.9% (13/14) of patients. Most patients responded well and the liver function was gradually improved, while antinuclear antibody titer might also significantly decrease and even turn negative. Long-term immunosuppressive therapy was not needed generally because relapse seldom occurred.

CONCLUSION: Different characteristics can be found in lipid-lowering agents-induced AIH patients compared to sporadic AIH patients. Liver function and antinuclear antibody tests with intensive follow-up may promote an immediate diagnosis and treatment.

Influence of ezetimibe on selected parameters of oxidative stress in rat liver subjected to ischemia/reperfusion

INTRODUCTION

Ischemia/reperfusion (I/R) is considered to be one of the main causes of liver damage after transplantation. The authors evaluated the effect of ezetimibe on selected oxidative stress parameters in ischemic/reperfused (I/R) rat liver.

MATERIAL AND METHODS

Rats were administered ezetimibe (5 mg/kg) (groups E and E-I/R) or saline solution (groups C and C-I/R) intragastrically for 21 days. Livers of animals in groups C-I/R and E-I/R were subjected to 60 min of partial ischemia (left lateral and median lobes) followed by 4 h of reperfusion. Alanine and asparagine aminotransferase (ALT, AST) activity was determined in blood before I/R and during reperfusion (at 15 and 240 min). After the reperfusion period, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GPx) were determined in liver homogenates using colorimetric methods.

RESULTS

Ezetimibe caused a significant increase in GSH level in groups subjected to I/R (E-I/R (99.91 ±9.01) vs. C-I/R (90.51 ±8.87), p < 0.05). Additionally, under I/R the decrease of GPx activity in the drug-treated group was lower compared to the non-treated group (E-I/R (3.88 ±1.11) vs. E (5.31 ±1.83), p = 0.076). Neither ezetimibe nor I/R affected SOD or MDA levels. I/R produced a significant increase in aminotransferase levels (ALT240-0: C-I/R (42.23 ±43.56) vs. C (9.75 ±11.09), and E-I/R (39.85 ±26.53) vs. E (4.38 ±1.36), p < 0.05 in both cases; AST 240-0: E-I/R (53.87 ±17.23) vs. E (24.10 ±9.66), p < 0.05) but no effect of ezetimibe on those enzymes was found.

CONCLUSIONS

Ezetimibe demonstrates antioxidant properties in rat livers subjected to I/R. However, neither a hepatoprotective nor a hepatotoxic effect of ezetimibe was demonstrated, regardless of I/R.

A reappraisal of the risks and benefits of treating to target with cholesterol lowering drugs

Atherosclerotic cardiovascular disease (CVD) is the number one cause of death globally, and lipid modification, particularly lowering of low density lipoprotein cholesterol (LDLc), is one of the cornerstones of prevention and treatment. However, even after lowering of LDLc to conventional goals, a sizeable number of patients continue to suffer cardiovascular events. More aggressive lowering of LDLc and optimization of other lipid parameters like triglycerides (TG) and high density lipoprotein cholesterol (HDLc) have been proposed as two potential strategies to address this residual risk. These strategies entail use of maximal doses of highly potent HMG CoA reductase inhibitors (statins) and combination therapy with other lipid modifying agents. Though statins in general are fairly well tolerated, adverse events like myopathy are dose related. There are further risks with combination therapy. In this article, we review the adverse effects of lipid modifying agents used alone and in combination and weigh these effects against the evidence demonstrating their efficacy in reducing cardiovascular events, cardiovascular mortality, and all cause mortality. For patients with established CVD, statins are the only group of drugs that have shown consistent reductions in hard outcomes. Though more aggressive lipid lowering with high dose potent statins can reduce rates of non fatal events and need for interventions, the incremental mortality benefits remain unclear, and their use is associated with a higher rate of drug related adverse effects. Myopathy and renal events have been a significant concern with the use of high potency statin drugs, in particular simvastatin and rosuvastatin. For patients who have not reached target LDL levels or have residual lipid abnormalities on maximal doses of statins, the addition of other agents has not been shown to improve clinical outcomes and carries an increased risk of adverse events. The clinical benefits of drugs to raise HDLc remain unproven. In patients without known cardiovascular disease, there is conflicting evidence as to the benefits of aggressive pursuit of numerical lipid targets, particularly with respect to all cause mortality. Certainly, in statin intolerant patients, alternative agents with a low side effect profile are desirable. Bile acid sequestrants are an effective and safe choice for decreasing LDLc, and omega-3 fatty acids are safe agents to decrease TG. There remains an obvious need to design and carry out large scale studies to help determine which agents, when combined with statins, have the greatest benefit on cardiovascular disease with the least added risk. These studies should be designed to assess the impact on clinical outcomes rather than surrogate endpoints, and require a comprehensive assessment and reporting of safety outcomes.

Biobehavioral measures as outcomes: a cautionary tale

This article discusses the use of biobehavioral measures as outcomes for health care intervention studies. Effect size (ES) values for salivary cortisol and observation-based measures of pain and agitation were examined. Effects pre to post treatment were assessed separately for nursing home residents with and without acute psychotic symptoms. This study revealed large positive effects on both pain and agitation measures in the group with acute psychotic symptoms and small-to-medium positive effects on these same measures in the group without acute psychotic symptoms. In both of these groups, the ES values were not consistently positive on the cortisol measures. Prior to determining whether a measure can be used to estimate minimum clinically important differences, it is essential to consider if the biomarker will be responsive to therapy in the populations and contexts being studied.

Ezetimibe therapy: mechanism of action and clinical update

The lowering of low-density lipoprotein cholesterol (LDL-C) is the primary target of therapy in the primary and secondary prevention of cardiovascular events. Although statin therapy is the mainstay for LDL-C lowering, a significant percentage of patients prescribed these agents either do not achieve targets with statin therapy alone or have partial or complete intolerance to them. For such patients, the use of adjuvant therapy capable of providing incremental LDL-C reduction is advised. One such agent is ezetimibe, a cholesterol absorption inhibitor that targets uptake at the jejunal enterocyte brush border. Its primary target of action is the cholesterol transport protein Nieman Pick C1 like 1 protein. Ezetimibe is an effective LDL-C lowering agent and is safe and well tolerated. In response to significant controversy surrounding the use and therapeutic effectiveness of this drug, we provide an update on the biochemical mechanism of action for ezetimibe, its safety and efficacy, as well as the results of recent randomized studies that support its use in a variety of clinical scenarios.

Ezetimibe inhibits expression of acid sphingomyelinase in liver and intestine

Ezetimibe inhibits cholesterol absorption in the intestine. Sphingomyelin has strong interactions with cholesterol. We investigated the effects of ezetimibe on Sphingomyelinase (SMase) expression in intestine and liver. After feeding rats with ezetimibe (5 mg/kg per day) for 14 days, acid SMase activities in the liver and in the proximal part of small intestine were reduced by 34 and 25%, respectively. Alkaline SMase (alk-SMase) was increased in the proximal part of the small intestine. Administration of lower doses of ezetimibe reduced acid SMase only in the liver by 14% (P < 0.05). In cell culture studies, ezetimibe decreased acid SMase activity in Hep G2 and Caco-2 cells dose-dependently. The reductions were more rapid for Hep G2 cells than for Caco-2 cells. Western blot showed that acid SMase protein was decreased in both Hep G2 and Caco-2 cells by 100 microM ezetimibe. The SM content was increased in Hep G2 cells but not Caco-2 cells, and total cholesterol content was increased in both cell lines 24 h after stimulation with 100 microM ezetimibe. Mevastatin, the inhibitor of cholesterol synthesis, induced a mild increase in acid SMase activity in Hep G2 cells but not Caco-2 cells. Following the reduction of acid SMase, ezetimibe at high dose slightly increased alk-SMase activity. In conclusion, the study demonstrates an inhibitory effect of ezetimibe on acid SMase activity and expression in both liver and intestine.

Impact of lipid lowering therapy on liver function

A cardiovascularis megbetegedések hazánkban is vezetik a morbiditási és mortalitási statisztikákat. Ezen betegségek kialakulásában jelentős szerepet játszik a hyperlipidaemia. A korábbi nagy prospektív multicentrikus tanulmányok azt igazolták, hogy a hatékony lipidcsökkentő kezelés jelentős mértékű cardiovascularis halálozás-összhalálozás csökkenést eredményez. Ez a hatás függ az LDL-C-csökkentés mértékétől, amely gyakran csak a nagy dózisban alkalmazott statinkészítményekkel éri el a kívánt szintet. A nagy dózisban alkalmazott statinok a betegek körülbelül 3%-ában hozhatnak létre májkárosító hatást. A szerzők jelen munkájukban röviden ismertetik a lipidcsökkentő gyógyszerek hatásait, azokat a mechanizmusokat, amelyek a szerek potenciális májkárosító hatásának hátterében állhatnak. Felhívják a figyelmet arra, hogy a korábbi gyakorlattól eltérően, emelkedett transzaminázszintek esetén, sőt, bizonyos májbetegségekben is biztonságosan alkalmazhatóak a lipidcsökkentő készítmények. Természetesen akkor, ha megfelelő dózisban vagy kombinációban alkalmazzuk a gyógyszereket, és figyelemmel vagyunk azon tényezőkre, amelyek fokozhatják a nem kívánt mellékhatásokat. Ezen szempontok betartása mellett magas cardiovascularis rizikójú, egyébként krónikus májbetegségben szenvedők számára is biztosíthatjuk a lipidcsökkentők nyújtotta kedvező hatásokat anélkül, hogy fokoznánk a máj károsodását.

Safety and effectiveness of ezetimibe in liver transplant recipients with hypercholesterolemia

Hypercholesterolemia is a common problem among transplant recipients. Despite package-insert warnings about the potential side effects of the use of statins in patients with chronic liver disease, they are often prescribed for liver transplant recipients. Unlike statins, ezetimibe acts through inhibition of enterohepatic recirculation of lipids. We report the effectiveness and safety of ezetimibe among liver transplant recipients because this has been evaluated previously only in kidney and heart transplant patients. A consecutive cohort of 25 liver graft recipients with serum low-density lipoprotein (LDL) levels > 100 mg/dL (2.5 mmol/L) after a mean (+/-standard deviation) of 55 +/- 21 months following liver transplantation received ezetimibe (10 mg orally every day) for at least 6 months. Serum lipid profiles, liver and renal function tests, and dosages and blood levels of the immunosuppression drugs at baseline, 3 months, and 6 months were prospectively collected. The overall mean age was 58 +/- 12 years, and 56% were males. Statin therapy and fibrates were already being used in 32% and 20% of recipients for elevated LDL and/or triglycerides, respectively. The immunosuppression regimen included cyclosporine in 48% of subjects, tacrolimus in 32%, sirolimus in 48%, and mycophenolate mofetil in 44%; only 12% were on oral prednisone with a maximum daily dose of 5 mg. After ezetimibe was started, an 18% reduction in LDL values was observed [at baseline, 147 +/- 35 mg/dL (3.8 +/- 0.9 mmol/L), and at 6 months, 120 +/- 31 mg/dL (3.1 +/- 0.8 mmol/L); P = 0.010]. After 6 months, an additional 32% achieved the target LDL level of <100 mg/dL. None of the remaining variables, including immunosuppression drug levels, varied significantly during ezetimibe therapy. None of the subjects required adjustments in their pharmacological dosages. One discontinued ezetimibe 3 months later because of cost, 2 subjects had minimal nausea, 1 subject had myalgias without a rise in creatine phosphokinase, and 1 subject had a transient elevation (3-5 times) in liver enzymes from baseline with increases in the total and indirect bilirubin levels. In conclusion, among liver transplant recipients, hypercholesterolemia can be effectively treated with ezetimibe with few side effects and no interaction with immunosuppressive regimens.

Review article: The use of potentially hepatotoxic drugs in patients with liver disease

BACKGROUND

Misconceptions surround the use of hepatotoxic drugs in chronic liver disease. While many prescription and over-the-counter (OTC) agents can be used safely, this often runs counter to labelled warnings/contraindications, especially for the statins and other commonly used agents.

AIM

To evaluate published data on the use of hepatotoxic drugs in chronic liver disease including pharmacokinetic changes in cirrhosis and drug interactions, where available, to formulate recommendations on their use.

METHODS

Using a combination of PubMed searches, review texts, the Physicians' Desk Reference and expert opinion, drugs considered at higher risk of hepatotoxicity in chronic liver disease were evaluated.

RESULTS

Most drugs and OTC products including herbals have not been formally studied in chronic liver disease, but available data suggest that several of the most commonly used agents, especially the statins, can be used safely. While there is an increased risk of drug-induced liver injury for drugs used in the treatment of tuberculosis and HIV patients with hepatitis B or C, recommendations for their safe use are emerging.

CONCLUSIONS

Although many clinicians remain hesitant to use hepatotoxic drugs in chronic liver disease, the database supporting this view is limited to just a few agents. Most medications can be used safely in patients with chronic liver disease with appropriate monitoring.

Serious drug-induced liver disease secondary to ezetimibe

Ezetimibe is the first member of a new family of lipid-lowering drugs that inhibits uptake of dietary and biliary cholesterol. It was approved by the FDA in 2002 for hypercholesterolemia alone or in combination with statins. Its use has been spreading over the last years. Ezetimibe was considered a safe drug. We report a case of a woman who developed a serious hepatocellular drug-induced liver disease after 4 mo therapy with 10 mg daily of ezetimibe. After withdrawal of the drug, the patient recovered slowly. Ezetimibe may produce serious toxic hepatitis and prompt withdrawal is mandatory in case of a significant abnormality in liver testing after beginning or during treatment with ezetimibe.

Severe jaundice following treatment with ezetimibe

Ezetimibe is a cholesterol-lowering agent that modulates intestinal absorption of sterols. It is well tolerated but hepatic toxicity has been reported when ezetimibe is used in conjunction with a statin medication. In this case report, we report severe isolated hyperbilirubinaemia occurring in a patient with occult cirrhosis, probably owing to nonalcoholic steatohepatitis, who was treated with ezetimibe alone. The adverse event started after ezetimibe therapy was initiated and resolved when the drug was stopped. We propose a mechanism for this reaction and believe that liver function should be monitored in patients with abnormal liver tests who are treated with ezetimibe, even if they are not on concomitant treatment with a statin.

Ezetimibe-associated adverse effects: what the clinician needs to know

OBJECTIVE

Ezetimibe is a relatively new lipid lowering agent, which is indicated for the treatment of primary hypercholesterolaemia, either as monotherapy or in combination with other hypolipidaemic drugs. The objective of the present article was to review the side effects attributed to ezetimibe administration and discuss their possible underlying mechanisms. Moreover, we aimed to comment on the possible drug interactions of ezetimibe and present current guidelines regarding its safe use.

METHODS

Relevant articles were identified through a PubMed search (up to June 2007).

RESULTS

Compelling evidence from the majority of the data reviewed here showed that adverse effects associated with ezetimibe use are few and mild without having been associated with serious clinical outcomes. In most studies ezetimibe has not been associated with increased rates of myopathy or rhabdomyolysis, whether used alone or in combination with statins, although there have been some case reports of myopathy attributed to this agent. Moreover, ezetimibe has been associated with mild elevations of liver transaminases, mainly in combination with a statin. Other side effects are extremely rare. It should be noted, however, there are no long-term safety data or outcome studies for ezetimibe yet.

CONCLUSIONS

Ezetimibe is a safe alternative option for hyperlipidaemic patients intolerant to other lipid lowering drugs as well as a beneficial supplementary agent for patients who do not reach the recommended serum cholesterol level with their current hypolipidaemic treatment. However, as is the case with all new medications, physicians should be alert to recognise adverse effects associated with ezetimibe and report them to regulatory authorities.

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.

Role of 57-72 loop in the allosteric action of bile salts on pancreatic IB phospholipase A(2): regulation of fat and cholesterol homeostasis

Mono- and biphasic kinetic effects of bile salts on the pancreatic IB phospholipase A2 (PLA2) catalyzed interfacial hydrolysis are characterized. This novel phenomenon is modeled as allosteric action of bile salts with PLA2 at the interface. The results and controls also show that these kinetic effects are not due to surface dilution or solubilization or disruption of the bilayer interface where in the mixed-micelles substrate replenishment becomes the rate-limiting step. The PLA2-catalyzed rate of hydrolysis of zwitterionic dimyristoylphosphatidylcholine (DMPC) vesicles depends on the concentration and structure of the bile salt. The sigmoidal rate increase with cholate saturates at 0.06 mole fraction and changes little at the higher mole fractions. Also, with the rate-lowering bile salts (B), such as taurochenodeoxycholate (TCDOC), the initial sigmoidal rate increase at lower mole fraction is followed by nearly complete reversal to the rate at the pre-activation level at higher mole fractions. The rate-lowering effect of TCDOC is not observed with the (62-66)-loop deleted DeltaPLA2, or with the Naja venom PLA2 that is evolutionarily devoid of the loop. The rate increase is modeled with the assumption that the binding of PLA2 to DMPC interface is cooperatively promoted by bile salt followed by allosteric k(cat)(*)-activation of the bound enzyme by the anionic interface. The rate-lowering effect of bile salts is attributed to the formation of a specific catalytically inert E(*)B complex in the interface, which is noticeably different than the 1:1 EB complex in the aqueous phase. The cholate-activated rate of hydrolysis is lowered by hypolidemic ezetimibe and guggul extract which are not interfacial competitive inhibitors of PLA2. We propose that the biphasic modulation of the pancreatic PLA2 activity by bile salts regulates gastrointestinal fat metabolism and cholesterol homeostasis.

Review article: drug hepatotoxicity

BACKGROUND

Drug toxicity is the leading cause of acute liver failure in the United States. Further understanding of hepatotoxicity is becoming increasingly important as more drugs come to market.

AIMS

(i) To provide an update on recent advances in our understanding of hepatotoxicity of select commonly used drug classes. (ii) To assess the safety of these medications in patients with pre-existing liver disease and in the post-liver transplant setting. (iii) To review relevant advances in toxicogenomics which contribute to the current understanding of hepatotoxic drugs.

METHODS

A Medline search was performed to identify relevant literature using search terms including 'drug toxicity, hepatotoxicity, statins, thiazolidinediones, antibiotics, antiretroviral drugs and toxicogenomics'.

RESULTS

Amoxicillin-clavulanic acid is one of the most frequently implicated causes of drug-induced liver injury worldwide. Statins rarely cause clinically significant liver injury, even in patients with underlying liver disease. Newer thiazolidinediones are not associated with the degree of liver toxicity observed with troglitazone. Careful monitoring for liver toxicity is warranted in patients who are taking antiretrovirals, especially patients who are co-infected with hepatitis B and C. Genetic polymorphisms among enzymes involved in drug metabolism and HLA types may account for some of the differences in individual susceptibility to drug hepatotoxicity.

CONCLUSIONS

Drug-induced hepatotoxicity will remain a problem that carries both clinical and regulatory significance as long as new drugs continue to enter the market. Future results from ongoing multicentre collaborative efforts may help contribute to our current understanding of hepatotoxicity associated with drugs.

Drug-induced liver disease in 2006

PURPOSE OF REVIEW

To identify the key publications of 2006 dealing with drug-induced liver injury.

RECENT FINDINGS

When given in therapeutic doses over 14 days, acetaminophen produced significant asymptomatic elevations in alanine aminotransferase among healthy volunteers, suggesting that subclinical injury may be more common than previously thought. Acute liver failure in children was shown to differ in several important respects from that seen in adults, notably a much lower incidence of acetaminophen toxicity with nearly half of all cases being indeterminate in origin. The first cases of hepatotoxicity with telithromycin, a new class of ketolide antibiotic, were described along with reports suggesting liver injury from ezetimibe among other agents. The potential for chronic injury to develop after acute drug-induced liver injury was analyzed in a large Swedish database; 5-6% of cases were judged to become chronic, with drugs causing cholestatic injury predominating. Among well described hepatotoxins, new reports appeared with highly active antiretroviral therapy agents, herbal therapies and several antibiotics. Finally, the safe use of pravastatin and pioglitazone was demonstrated in patients with chronic liver disease in controlled clinical trials.

SUMMARY

Drug-induced liver injury remains an important concern for many existing drugs as well as for agents in development.

Non-low-density lipoprotein cholesterol-associated actions of ezetimibe: an overview

Ezetimibe, an intestinal cholesterol absorption inhibitor, lowers circulating low-density lipoprotein cholesterol (LDL-C) levels both when administered as monotherapy and in combination with other hypolipidaemic drugs, mostly statins. This review focuses on the effects of ezetimibe on non-LDL-C-associated variables. In most studies, ezetimibe effectively reduced triglyceride and increased high density lipoprotein cholesterol levels. The authors also consider the effect of ezetimibe on other variables such as C-reactive protein levels, insulin sensitivity and endothelial function. Ezetimibe is useful in patients with sitosterolaemia (a rare inherited disorder) as it significantly reduces plasma phytosterol concentrations. Ezetimibe fulfils two of the three essential characteristics of any drug (efficacy and safety). However, clinical studies are required to provide evidence of its ability to reduce vascular events.