The effect of fluvastatin on the pharmacokinetics and pharmacodynamics of ezetimibe

Maternal Ezetimibe Concentrations Measured in Breast Milk and Its Use in Breastfeeding Infant Exposure Predictions

BACKGROUND

Lactating mothers taking ezetimibe, an antihyperlipidemic agent, may be hesitant to breastfeed despite the known benefit of breastfeeding to both mother and infant. Currently, no data exist on the presence or concentration of ezetimibe and its main active metabolite, ezetimibe-glucuronide (EZE-glucuronide), in human breast milk.

METHODS

Voluntary breast milk samples containing ezetimibe and EZE-glucuronide were attained from lactating mothers taking ezetimibe as part of their treatment. An assay was developed and validated to measure ezetimibe and EZE-glucuronide concentrations in breast milk. A workflow that utilized a developed and evaluated pediatric physiologically based pharmacokinetic (PBPK) model, the measured concentrations in milk, and weight-normalized breast milk intake volumes was applied to predict infant exposures and determine the upper area under the curve ratio (UAR).

RESULTS

Fifteen breast milk samples from two maternal-infant pairs were collected. The developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay showed an analytical range of 0.039-5.0 ng/mL and 0.39-50.0 ng/mL for ezetimibe and EZE-glucuronide, respectively. The measured concentrations in the breast milk samples were 0.17-1.02 ng/mL and 0.42-2.65 ng/mL of ezetimibe and EZE-glucuronide, respectively. The evaluated pediatric PBPK model demonstrated minimal exposure overlap in adult therapeutic dose and breastfed infant simulated area under the concentration-time curve from time zero to 24 h (AUC24). Calculated UAR across infant age groups ranged from 0.0015 to 0.0026.

CONCLUSIONS

PBPK model-predicted ezetimibe and EZE-glucuronide exposures and UAR suggest that breastfeeding infants would receive non-therapeutic exposures. Future work should involve a 'mother-infant pair study' to ascertain breastfed infant plasma ezetimibe and EZE-glucuronide concentrations to confirm the findings of this work.

Pharmacokinetic interactions and tolerability of rosuvastatin and ezetimibe: an open-label, randomized, multiple-dose, crossover study in healthy male volunteers

Purpose

Rosuvastatin is a synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor that effectively reduces low-density lipoprotein cholesterol levels. However, statin monotherapy does not always achieve acceptable low-density lipoprotein cholesterol levels in patients with severe hypercholesterolemia. Ezetimibe, a selective cholesterol-absorption inhibitor, is approved for use as a monotherapy or combination therapy with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors for patients with hypercholesterolemia. The aim of this study was to examine the pharmacokinetics (PKs) of drug interactions between rosuvastatin and ezetimibe, and the tolerability of combined administration in healthy Korean male volunteers.

Subjects and methods

Healthy subjects (n=24) were randomly allocated to 3 treatment groups: rosuvastatin (20 mg) alone, ezetimibe (10 mg) alone, and rosuvastatin (20 mg) plus ezetimibe (10 mg). The drugs were taken once every 24 hours over a period of 10 days. Blood samples were collected to analyze steady-state PKs.

Results

All adverse events observed during the study were mild, and the frequency was no higher for combined administration than for mono administration. For rosuvastatin, the steady-state mean ratios (90% CI) of the combined over the single dose were 1.076 (1.019–1.136) for AUC_τ,ss and 1.099 (1.003–1.204) for concentration at steady-state, respectively. In the case of free and total ezetimibe, the steady-state ratios of AUC_τ,ss and concentration at steady-state were 1.131 (1.051–1.218) and 1.182 (1.038–1.346), and 1.055 (0.969–1.148) and 0.996 (0.873–1.135), respectively.

Conclusion

Combined administration of rosuvastatin and ezetimibe was well tolerated. No clinically significant PK interactions between rosuvastatin and ezetimibe were observed when the 2 drugs were administered concomitantly.

Rationalization and prediction of in vivo metabolite exposures: the role of metabolite kinetics, clearance predictions and in vitro parameters

IMPORTANCE OF THE FIELD

Due to growing concerns over toxic or active metabolites, significant efforts have been focused on qualitative identification of potential in vivo metabolites from in vitro data. However, limited tools are available to quantitatively predict their human exposures.

AREAS COVERED IN THIS REVIEW

Theory of clearance predictions and metabolite kinetics is reviewed together with supporting experimental data. In vitro and in vivo data of known circulating metabolites and their parent drugs were collected and the predictions of in vivo exposures of the metabolites were evaluated.

WHAT THE READER WILL GAIN

The theory and data reviewed will be useful in early identification of human metabolites that will circulate at significant levels in vivo and help in designing in vivo studies that focus on characterization of metabolites. It will also assist in rationalization of metabolite-to-parent ratios used as markers of specific enzyme activity.

TAKE HOME MESSAGE

The relative importance of a metabolite in comparison to the parent compound as well as other metabolites in vivo can only be predicted using the metabolite's in vitro formation and elimination clearances, and the in vivo disposition of a metabolite can only be rationalized when the elimination pathways of that metabolite are known.

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.

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.

Reaching goal in hypercholesterolaemia: dual inhibition of cholesterol synthesis and absorption with simvastatin plus ezetimibe

Lowering serum cholesterol levels reduces the risk of coronary heart disease (CHD)-related events. Statins are commonly prescribed as first-line treatment but many patients at high-risk for CHD still fail to reach their cholesterol or low-density lipoprotein cholesterol (LDL-C) goals with statin monotherapy. National and international guidelines for the prevention of CHD recommend the modification of lipid profiles and particularly LDL-C [e.g. the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III; 2001) and Third Joint Task Force of European and other Societies on Cardiovascular Disease Prevention in Clinical Practice (2003) Guidelines]. Several recent clinical trials indicated an added benefit from aggressive lowering of LDL-C levels. Based on these findings, the NCEP ATP III revised the LDL-C target from < 100 mg/dL (2.6 mmol/L) to < 70 mg/dL (1.8 mmol/L) (optional target) for very high-risk patients and < 130 mg/dL (3.4 mmol/L) to < 100 mg/dL (2.6 mmol/L) for moderately high-risk patients. For patients who fail to achieve their LDL-C target, inhibiting the two main sources of cholesterol - synthesis and uptake - can produce more effective lipid lowering, allowing more patients to reach their LDL-C goal. Ezetimibe is a highly-selective inhibitor of cholesterol absorption and simvastatin is an evidence-based inhibitor of cholesterol synthesis. The LDL-C-lowering efficacy of targeting both major sources of cholesterol with ezetimibe plus simvastatin was demonstrated in several multicentre, double-blind, placebo-controlled trials in patients with hypercholesterolaemia. For patients who do not reach their cholesterol goal with a statin, adding ezetimibe 10 mg significantly reduces LDL-C compared with statin monotherapy. Thus, this treatment option may help patients reach the new 'stricter' cholesterol goals. This review, based on a Medline database search from January 2000 to August 2005, considers the LDL-C-lowering efficacy of ezetimibe and discusses the role of this agent for patients who fail to achieve guideline cholesterol goals with statin monotherapy.