Effects of Ezetimibe on Cyclosporine Pharmacokinetics in Healthy Subjects

Management of dyslipidemia in adult solid organ transplant recipients

Solid organ transplantation (SOT) has revolutionized treatment of end-stage disease. Improvements in the SOT continuum of care have unmasked a significant burden of cardiovascular disease, manifesting as a leading cause of morbidity and mortality. Although several risk factors for development of post-transplant cardiovascular disease exist, dyslipidemia remains one of the most frequent and modifiable risks. An important contributor to dyslipidemia in SOT recipients is the off-target metabolic effects of immunosuppressive medications, which may alter lipoproteins and their metabolism. Dyslipidemia management is paramount as lipid-lowering therapy with statins has demonstrated reductions in graft vasculopathy, decreased rejection rates, and improved survival. Several nonstatin medication options are available, but data supporting their benefit in the SOT population are minimal, typically extrapolated from studies in the general population. Further compounding dyslipidemia management is the complex interplay of drug interactions between lipid-lowering and immunosuppressant medications, which can result in serious toxicity and/or therapeutic failure.

An observational study of ezetimibe in cardiac transplant recipients receiving calcineurin inhibitors

BACKGROUND

Cardiac transplant patients are at risk for developing cardiac allograft vasculopathy, and dyslipidemia in this patient population has been associated with increased risk. Data evaluating the efficacy and safety of ezetimibe in this population are minimal.

OBJECTIVES

The purpose of this study was to assess the effects of ezetimibe, alone or in combination with other lipid-lowering agents, in cardiac transplant recipients receiving calcineurin inhibitors (CNIs).

METHODS

This study was a single-center retrospective chart review. Data on demographics, medications prescribed for dyslipidemia and prevention of transplant rejection, results of lipid panels, CNI blood concentrations, and adverse effects were extracted from medical records of cardiac transplant recipients who were prescribed ezetimibe, either alone or in combination with other lipid-lowering agents, and seen at least once in a 12-month period at a cardiac transplantation clinic of an 800-bed teaching hospital.

RESULTS

There were 71 patients prescribed ezetimibe in whom a safety analysis was performed. Approximately 49% (n = 35) were included in the analysis for lipid lowering. Ezetimibe significantly decreased low-density lipoprotein cholesterol (LDL-C; 129 mg/dL vs 94 mg/dL, P < .0001), non-high-density lipoprotein cholesterol (non-HDL-C; 170 mg/dL vs 127.5 mg/dL, P = .0058), and total cholesterol (236 mg/dL vs 200 mg/dL, P < .0001). There was no significant change in HDL-C and triglycerides as compared with baseline. The proportion of patients achieving goal LDL-C < 100 mg/dL significantly increased from 11.5% at baseline to 60.5% after the addition of ezetimibe (P < .0001). Ezetimibe had no measurable effect on blood CNI concentrations or doses. Adverse effects were reported by 15.5% of patients (n = 11), with 4% (n = 3) of patients discontinuing therapy. The most common complaints were gastrointestinal intolerance and myalgia.

CONCLUSIONS

Ezetimibe was associated with lower LDL-C in cardiac transplant recipients either as combination therapy in patients with elevated LDL-C or as monotherapy, with a low frequency of adverse effects.

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.

Effect of cyclosporine on the pharmacokinetics of aliskiren in healthy subjects

To explore the clinical relevance of inhibition of multidrug resistance transporter 1 and organic anion transporting polypeptide transporter, a drug-drug interaction study was conducted using aliskiren and cyclosporine. This was an open-label, single-sequence, parallel-group, single-dose study in healthy subjects. Subjects (n = 14) first received aliskiren 75 mg orally (period 1), followed by aliskiren 75 mg + cyclosporine 200 mg (period 2) after a 7-day washout period, and aliskiren 75 mg + cyclosporine 600 mg (period 3) after a 14-day washout period. Safety and pharmacokinetics were analyzed during each period. The primary objective was to characterize pharmacokinetics of aliskiren (single-dose and combination with cyclosporine). The increases in area under the time-concentration curve from time 0 to infinity and maximum concentration associated with cyclosporine 200 mg or 600 mg were 4- to 5-fold and 2.5-fold, respectively. Mean half-life increased from 25 to 45 hours. Based on comparison to literature, a single-dose of aliskiren 75 mg did not alter the pharmacokinetics of cyclosporine. Aliskiren 75 mg was well tolerated. Combination with cyclosporine increased the number of adverse events, mainly hot flush and gastrointestinal symptoms, with no serious adverse events. Two adverse events led to withdrawal (ligament rupture, not suspected to be study-drug related; and vomiting, suspected to be study-drug related). Laboratory parameters, vital signs, and electrocardiographs showed no time- or treatment-related changes. As cyclosporine significantly altered the pharmacokinetics of aliskiren in humans, its use with aliskiren is not recommended.

Impact of ezetimibe on cholesterol subfractions in dyslipidemic cardiac transplant recipients receiving statin therapy

BACKGROUND

Ezetimibe decreases cholesterol in cardiac transplant recipients intolerant to statins therapy. The effects of ezetimibe in addition to statins therapy and its relationship with the magnitude of dyslipidemia and statins utilization have not been studied in cardiac transplant recipients.

METHODS

The design of this investigation was a retrospective case control study. Twenty-two patients receiving the combination of therapy of statins plus ezetimibe were compared with 43 patients treated with statins only. The endpoints were assessed after three months of follow-up.

RESULTS

The addition of ezetimibe decreased low density lipoprotein-cholesterol by 25% compared with a 4% increase in patients receiving statins only. The impact of ezetimibe was similar regardless of the magnitude of dyslipidemia or statins dosage. Ezetimibe increase high density lipoprotein (HDL)-cholesterol only in patients with baseline HDL-cholesterol above 1.3 mM/L (p < 0.05). There was an asymptomatic, but significant increase in creatinine kinase level [+31.4 +/- 8.1 (ezetimibe) vs. + 1.5 +/- 5.0 mM/L (placebo); p = 0.005].

CONCLUSION

Ezetimibe therapy provides a significant reduction in most cholesterol subfractions regardless of the magnitude of dyslipidemia and statins dosage.

Adverse drug reactions in patients with cardiovascular disease

Adverse drug reactions (ADRs) occur frequently in modern medical practice, increasing morbidity and mortality and inflating the cost of care. Patients with cardiovascular disease are particularly vulnerable to ADRs due to their advanced age, polypharmacy, and the influence of heart disease on drug metabolism. The ADR potential for a particular cardiovascular drug varies with the individual, the disease being treated, and the extent of exposure to other drugs. Knowledge of this complex interplay between patient, drug, and disease is a critical component of safe and effective cardiovascular disease management. The majority of significant ADRs involving cardiovascular drugs are predictable and therefore preventable. Better patient education, avoidance of polypharmacy, and clear communication between physicians, pharmacists, and patients, particularly during the transition between the inpatient to outpatient settings, can substantially reduce ADR risk.

Niemann-pick C1-like 1 mediates alpha-tocopherol transport

Dietary lipids and fat-soluble micronutrients are solubilized in mixed micelles and absorbed in the small intestine. Based on an assumption that cholesterol and other fat-soluble molecules share a number of transport mechanisms and the fact that Niemann-Pick C1-like 1 (NPC1L1) is critical for intestinal cholesterol absorption, we hypothesized that some fat-soluble molecules may be transported by NPC1L1. To investigate this hypothesis, we compared the cellular uptake and inhibitory effects of ezetimibe, the molecular target of which is NPC1L1, between cholesterol and some fat-soluble molecules using rat NPC1L1-overexpressing Caco-2 cells. The in vitro analysis suggested that NPC1L1 mediates the uptake of alpha-tocopherol (vitamin E) in an ezetimibe-sensitive manner as well as the uptake of cholesterol but does not mediate the uptake of retinol (vitamin A) or cyclosporin A. To confirm the ezetimibe-sensitive uptake of alpha-tocopherol in vivo, we performed an in vivo absorption study using rats and the results suggested a physiologically significant role of NPC1L1-mediated alpha-tocopherol absorption. Furthermore, using human NPC1L1 overexpression system, we demonstrated that both cholesterol and alpha-tocopherol uptake was also significantly increased by the overexpression of human NPC1L1 and ezetimibe inhibited their uptake. Mutual inhibition studies of cholesterol and alpha-tocopherol in human NPC1L1-mediated uptake revealed the inhibitory effect of cholesterol and the stimulatory effect of alpha-tocopherol on the NPC1L1-mediated transport of both substrates. The present data suggest, for the first time, that NPC1L1 has the ability to transport alpha-tocopherol and that ezetimibe is able to inhibit the intestinal absorption of alpha-tocopherol.

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.