Phase 1 Study of the Effect of Icosapent Ethyl on Warfarin Pharmacokinetic and Anticoagulation Parameters

Pharmacokinetics of current and emerging treatments for hypercholesterolemia

Introduction: Reduction of low-density-lipoprotein cholesterol (LDL-C) and other apolipoprotein B (apoB)-containing lipoproteins reduces cardiovascular (CV) events and greater reductions have greater benefits. Current lipid treatments cannot always achieve desirable LDL-C targets and additional or alternative treatments are often needed.Areas covered: In this article, we review the pharmacokinetics of the available and emerging treatments for hypercholesterolemia and focus on recently approved drugs and those at a late stage of development.Expert opinion: Statin pharmacokinetics are well known and appropriate drugs and doses can usually be chosen for individual patients to achieve LDL-C targets and avoid adverse effects and drug-drug interactions. Ezetimibe, icosapent ethyl and the monoclonal antibodies evolocumab and alirocumab have established efficacy and safety. Newer oral agents including pemafibrate and bempedoic acid have generally favorable pharmacokinetics supporting use in a wide range of patients. RNA-based therapies with antisense oligonucleotides are highly specific for their targets and those inhibiting apoB, apoCIII, angiopoietin-like protein 3 and lipoprotein(a) have shown promising results. The small-interfering RNA inclisiran has the notable advantage that a single subcutaneous administration may be effective for up to 6 months. The CV outcome trial results and long term safety data are eagerly awaited for these new agents.

Cardiovascular disease and omega-3s: Prescription products and fish oil dietary supplements are not the same

BACKGROUND AND PURPOSE

Despite achievement of optimal low-density lipoprotein cholesterol (LDL-C) control with statin therapy, patients with elevated triglycerides (TGs) and residual cardiovascular risk are commonly encountered in clinical practice.

METHODS

We present information from completed and ongoing clinical trials examining Rx omega-3s for TG-lowering and omega-3 dietary supplements to highlight important differences affecting patient management for nurse practitioners.

CONCLUSIONS

Rx omega-3s demonstrate robust reductions in TGs and may have a role in reducing residual cardiovascular risk. Products containing docosahexaenoic acid (DHA) may raise LDL-C and should not be substituted for Rx eicosapentaenoic acid (EPA)-only icosapent ethyl, which does not raise LDL-C. Omega-3 dietary supplements (e.g., fish oils containing EPA and DHA) may be used for general health promotion; however, they are not regulated as medications and concerns regarding quality, purity, safety, and variability of content exist. It is important to advise patients that omega-3 dietary supplements are not medications and should not be substituted for Rx omega-3s. Large-scale cardiovascular outcomes studies are underway for Rx omega-3s in statin-treated patients.

IMPLICATIONS FOR PRACTICE

Nurse practitioners can take an active role in reducing residual cardiovascular risk and educating patients about important differences between Rx omega-3s and fish oil supplements.

The Impact of the Hepatocyte-to-Plasma pH Gradient on the Prediction of Hepatic Clearance and Drug-Drug Interactions for CYP2C9 and CYP3A4 Substrates

Surrogate assays for drug metabolism and inhibition are traditionally performed in buffer systems at pH 7.4, despite evidence that hepatocyte intracellular pH is 7.0. This pH gradient can result in a pK_a-dependent change in intracellular/extracellular concentrations for ionizable drugs that could affect predictions of clearance and P450 inhibition. The effect of microsomal incubation pH on in vitro enzyme kinetic parameters for CYP2C9 (diclofenac, (S)-warfarin) and CYP3A4 (midazolam, dextromethorphan, testosterone) substrates, enzyme specific reversible inhibitors (amiodarone, desethylamiodarone, clozapine, nicardipine, fluconazole, fluvoxamine, itraconazole) and a mechanism-based inhibitor (amiodarone) was investigated. Intrinsic clearance through CYP2C9 significantly increased (25% and 50% for diclofenac and (S)-warfarin respectively) at intracellular pH 7.0 compared with traditional pH 7.4. The CYP3A4 substrate dextromethorphan intrinsic clearance was decreased by 320% at pH 7.0, while midazolam and testosterone remained unchanged. Reversible inhibition of CYP2C9 was less potent at pH 7.0 compared with 7.4, while CYP3A4 inhibition potency was variably affected. Maximum enzyme inactivation rate of amiodarone toward CYP2C9 and CYP3A4 decreased at pH 7.0, while the irreversible inhibition constant remained unchanged for CYP2C9, but decreased for CYP3A4 at pH 7.0. Predictions of clearance and drug-drug interactions made through physiologically based pharmacokinetic models were improved with the inclusion of predicted intracellular concentrations based at pH 7.0 and in vitro parameters determined at pH 7.0. No general conclusion on the impact of pH could be made and therefore a recommendation to change buffer pH to 7.0 cannot be made at this time. It is recommended that the appropriate hepatocyte intracellular pH 7.0 be used for in vitro determinations when in vivo predictions are made.

No Effect of Omega-3 Carboxylic Acids on Pharmacokinetics/Pharmacodynamics of Warfarin or on Platelet Function When Co-administered with Acetylsalicylic Acid: Results of Two Phase I Studies in Healthy Volunteers

BACKGROUND

Omega-3 carboxylic acids (OM3-CA) can lower triglyceride levels.

OBJECTIVE

Our objective was to assess the effects of OM3-CA on warfarin pharmacokinetics and pharmacodynamics and on acetylsalicylic acid (ASA)-dependent and independent platelet activation when co-administered with ASA in two phase I studies.

METHODS

In ECLIPSE II (NCT01431690), 26 participants received warfarin 25 mg on days 1 and 22 and OM3-CA 4 g once daily from day 8 to day 28. In OM-EPA-007 (NCT01486433), 52 participants received simvastatin 40 mg plus ASA 81 mg once daily for 14 days, with or without OM3-CA 4 g. Lack of a drug-drug interaction was indicated when 90% confidence intervals (CIs) fell entirely within the range 80-125% for least-squares mean (LSM) ratios of area under the concentration-time curve (AUC), maximum observed plasma concentration (C _max), international normalized ratio (INR) AUC to 168 h and maximum INR.

RESULTS

In ECLIPSE II, 90% CIs for LSM ratios of with:without OM3-CA fell within 80-125% for AUC and C _max of S- and R-warfarin enantiomers. The 90% CIs for LSM ratios of with:without OM3-CA fell within 80-125% for INR AUC to 168 h after dosing and for maximum INR of warfarin. In OM-EPA-007, no significant effect of OM3-CA was observed on ASA-dependent or ASA-independent platelet activation. No deaths or serious adverse events occurred in either study.

CONCLUSION

OM3-CA did not affect the pharmacokinetics or pharmacodynamics of warfarin or the pharmacodynamic effects of ASA. OM3-CA did not affect platelet function when co-administered with ASA.

Prescription omega-3 fatty acid products containing highly purified eicosapentaenoic acid (EPA)

The omega-3 fatty acid eicosapentaenoic acid (EPA) has multiple actions potentially conferring cardiovascular benefit, including lowering serum triglyceride (TG) and non-high-density lipoprotein cholesterol (non-HDL-C) levels and potentially reducing key steps in atherogenesis. Dietary supplements are a common source of omega-3 fatty acids in the US, but virtually all contain docosahexaenoic acid (DHA) in addition to EPA, and lipid effects differ between DHA and EPA. Contrary to popular belief, no over-the-counter omega-3 products are available in the US, only prescription products and dietary supplements. Among the US prescription omega-3 products, only one contains EPA exclusively (Vascepa); another closely related prescription omega-3 product also contains highly purified EPA, but is approved only in Japan and is provided in different capsule sizes. These high-purity EPA products do not raise low-density lipoprotein cholesterol (LDL-C) levels, even in patients with TG levels >500 mg/dL, in contrast to the increase in LDL-C levels with prescription omega-3 products that also contain DHA. The Japanese prescription EPA product was shown to significantly reduce major coronary events in hypercholesterolemic patients when added to statin therapy in the Japan EPA Lipid Intervention Study (JELIS). The effects of Vascepa on cardiovascular outcomes are being investigated in statin-treated patients with high TG levels in the Reduction of Cardiovascular Events With EPA-Intervention Trial (REDUCE-IT).

Evaluation of pharmacokinetic and pharmacodynamic interactions when lenalidomide is co-administered with warfarin in a randomized clinical trial setting

BACKGROUND AND OBJECTIVE

Lenalidomide is an oral immunomodulatory drug used to treat multiple myeloma and some other hematological malignancies. Warfarin is often used concomitantly as prophylaxis against potential venous thromboembolism associated with lenalidomide treatment. The objective of this study was to evaluate the pharmacokinetic and pharmacodynamic drug interactions between lenalidomide and warfarin in healthy volunteers.

METHODS

This was a double-blind, placebo-controlled, randomized, two-period crossover study. Eighteen healthy male and female subjects were treated with 10 mg/day lenalidomide or placebo for 9 days. A single oral 25 mg dose of warfarin was administered on Day 4 of each treatment period. Blood was sampled to determine international normalized ratio (INR), prothrombin time (PT), and area under the plasma concentration-time curve (AUC) and maximum plasma concentration (C max) warfarin and lenalidomide.

RESULTS

The 90 % confidence intervals (CI) for the ratio of AUC or Cmax geometric means between co-administration with lenalidomide and placebo were within the 80-125 % bioequivalence bounds for R-warfarin and S-warfarin. The 90 % CI for the ratio of area under the INR curve from time zero until 144 hours after dosing (AUCINR, 0-144) or the peak INR geometric means between co-administration with lenalidomide versus placebo was also within the 85-125 % bounds. Additionally, the AUC and C max values of lenalidomide were not altered by co-administration with warfarin.

CONCLUSION

Co-administration of lenalidomide with warfarin did not alter the plasma exposure or anticoagulant effect to warfarin or the plasma exposure to lenalidomide, indicating that no dose adjustment of either drug is needed when these two drugs are co-administered.

The clinical relevance of omega-3 fatty acids in the management of hypertriglyceridemia

Hypertriglyceridemia (triglycerides > 150 mg/dL) affects ~25 % of the United States (US) population and is associated with increased cardiovascular risk. Severe hypertriglyceridemia (≥ 500 mg/dL) is also a risk factor for pancreatitis. Three omega-3 fatty acid (OM3FA) prescription formulations are approved in the US for the treatment of adults with severe hypertriglyceridemia: (1) OM3FA ethyl esters (OM3EE), a mixture of OM3FA ethyl esters, primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Lovaza®, Omtryg™, and generics); (2) icosapent ethyl (IPE), EPA ethyl esters (Vascepa®); and (3) omega-3 carboxylic acids (OM3CA), a mixture of OM3FAs in free fatty acid form, primarily EPA, DHA, and docosapentaenoic acid (Epanova®). At approved doses, all formulations substantially reduce triglyceride and very-low-density lipoprotein levels. DHA-containing formulations may also increase low-density lipoprotein cholesterol. However, this is not accompanied by increased non-high-density lipoprotein cholesterol, which is thought to provide a better indication of cardiovascular risk in this patient population. Proposed mechanisms of action of OM3FAs include inhibition of diacylglycerol acyltransferase, increased plasma lipoprotein lipase activity, decreased hepatic lipogenesis, and increased hepatic β-oxidation. OM3CA bioavailability (area under the plasma concentration-time curve from zero to the last measurable concentration) is up to 4-fold greater than that of OM3FA ethyl esters, and unlike ethyl esters, the absorption of OM3CA is not dependent on pancreatic lipase hydrolysis. All three formulations are well tolerated (the most common adverse events are gastrointestinal) and demonstrate a lack of drug-drug interactions with other lipid-lowering drugs, such as statins and fibrates. OM3FAs appear to be an effective treatment option for patients with severe hypertriglyceridemia.

Prescription omega-3 fatty acid products: considerations for patients with diabetes mellitus

Type 2 diabetes mellitus (T2DM) and metabolic syndrome contribute to hypertriglyceridemia, which may increase residual risk of cardiovascular disease in patients with elevated triglyceride (TG) levels despite optimal low-density lipoprotein cholesterol (LDL-C) levels with statin therapy. Prescription products containing the long-chain omega-3 fatty acids (OM3FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are an effective strategy for reducing TG levels. This article provides an overview of prescription OM3FAs, including relevant clinical data in patients with T2DM and/or metabolic syndrome. Prescription OM3FAs contain either combinations of DHA and EPA (omega-3-acid ethyl esters, omega-3-carboxylic acids, omega-3-acid ethyl esters A) or EPA alone (icosapent ethyl). These products are well tolerated and can be used safely with statins. Randomized controlled trials have demonstrated that all prescription OM3FAs produce statistically significant reductions in TG levels compared with placebo; however, differential effects on LDL-C levels have been reported. Products containing DHA may increase LDL-C levels, whereas the EPA-only product did not increase LDL-C levels compared with placebo. Because increases in LDL-C levels may be unwanted in patients with T2DM and/or dyslipidemia, the EPA-only product should not be replaced with products containing DHA. Available data on the effects of OM3FAs in patients with diabetes and/or metabolic syndrome support that these products can be used safely in patients with T2DM and have beneficial effects on atherogenic parameters; in particular, the EPA-only prescription product significantly reduced TG, non-high-density lipoprotein cholesterol, Apo B, remnant lipoprotein cholesterol, and high-sensitivity CRP levels without increasing LDL-C levels compared with placebo. Ongoing studies of the effects of prescription OM3FAs on cardiovascular outcomes will help determine whether these products will emerge as effective add-on options to statin therapy for reduction of residual cardiovascular disease risk.

Investigation of the effect of macitentan on the pharmacokinetics and pharmacodynamics of warfarin in healthy male subjects

BACKGROUND AND OBJECTIVES

Macitentan is a novel dual endothelin receptor antagonist recently approved for the treatment of pulmonary arterial hypertension (PAH). Warfarin, an anticoagulant often prescribed to patients with PAH, has a narrow therapeutic index and is prone to potential interactions with drugs. This study assessed the effects of macitentan on the pharmacokinetics and pharmacodynamics of single-dose warfarin in healthy subjects.

METHODS

This was a randomised, open-label, single-centre, two-way crossover (treatment A followed by treatment B, or vice versa), phase I study in 14 healthy male subjects. Treatment A was a loading dose of macitentan 30 mg on Day 1 followed by 10 mg once daily for 8 days, with a single 25 mg dose of warfarin on Day 4. Treatment B was a single dose of warfarin on Day 1. Blood samples were assessed for warfarin pharmacokinetics (R- and S-warfarin) and pharmacodynamics [international normalised ratio (INR) and factor VII]. Plasma trough concentrations of macitentan and its active metabolite (ACT-132577) and the safety and tolerability of each treatment were also assessed.

RESULTS

Plasma concentrations of R- and S-warfarin were similar in both treatment periods. Warfarin did not affect the mean trough plasma concentrations of macitentan or ACT-132577. Macitentan did not affect the pharmacodynamics of warfarin; the mean INR and factor VII activity versus time profiles were similar with and without macitentan.

CONCLUSIONS

The absence of effect of macitentan on the pharmacokinetics and pharmacodynamics of a single dose of warfarin suggests that both drugs can be concomitantly administered without need for dose adjustment.

Effect of concomitant icosapent ethyl (eicosapentaenoic acid ethyl ester) on the pharmacokinetics of atorvastatin

BACKGROUND AND OBJECTIVE

Icosapent ethyl is a high-purity prescription form of eicosapentaenoic acid ethyl ester approved as an adjunct to diet to reduce triglyceride levels in adult patients with triglyceride levels ≥500 mg/dL (≥5.65 mmol/L). The objective of this open-label, drug-drug interaction study was to examine the effects of icosapent ethyl on the steady-state pharmacokinetics of atorvastatin, a commonly prescribed medication in patients with dyslipidaemia.

METHODS

Thirty healthy subjects received atorvastatin 80 mg/day on days 1-7, icosapent ethyl 4 g/day on days 8-28, and co-administration on days 29-35. Primary end-points were natural log-transformed maximum plasma concentration (C(max)) and area under the concentration-versus-time curve from 0 to 24 h (AUC(0-24)) for atorvastatin, 2-hydroxyatorvastatin, and 4-hydroxyatorvastatin with and without icosapent ethyl.

RESULTS

Of the 30 subjects enrolled, 26 completed the study. The 90% confidence intervals for C(max) and AUC(0-24) least-squares geometric mean ratios were within the 0.80-1.25 bounds. Concomitant administration of icosapent ethyl and atorvastatin was safe and well tolerated and icosapent ethyl did not significantly change the steady state C(max) and AUC(0-24) of atorvastatin, 2-hydroxyatorvastatin, or 4-hydroxyatorvastatin.

CONCLUSIONS

At steady-state concentrations, icosapent ethyl did not have an effect on the pharmacokinetics of atorvastatin. Co-administration of icosapent ethyl and atorvastatin was safe and well tolerated in healthy adult subjects.

Effects of Icosapent Ethyl (Eicosapentaenoic Acid Ethyl Ester) on Pharmacokinetic Parameters of Rosiglitazone in Healthy Subjects

Background

Icosapent ethyl is a high-purity form of eicosapentaenoic acid ethyl ester approved to reduce triglyceride levels in adults with triglycerides ≥500 mg/dL. Candidates for triglyceride-lowering therapy include patients with diabetes mellitus who may be receiving rosiglitazone. We assessed the effects of icosapent ethyl on the pharmacokinetic parameters of rosiglitazone.

Methods

Subjects received a single 8-mg oral dose of rosiglitazone alone and with oral icosapent ethyl 4 g/day in this open-label drug–drug interaction study. Pharmacokinetic end points included area under the concentration versus time curve from time zero to infinity (AUC_0–inf) and maximum observed concentration (C_max) for rosiglitazone with and without icosapent ethyl.

Results

Of 30 subjects enrolled, 28 completed the study. Icosapent ethyl 4 g/day at steady-state did not significantly change the single-dose AUC_0–inf or C_max of rosiglitazone 8 mg. Least squares geometric mean ratios (90% confidence interval) for AUC_0–inf and C_max of rosiglitazone given with icosapent ethyl versus rosiglitazone alone were 0.90 (87.00–93.40) and 1.01 (92.02–109.9), respectively. No serious adverse events were reported and no subject discontinued due to an adverse event.

Conclusions

At steady-state concentrations, icosapent ethyl did not inhibit the pharmacokinetics of rosiglitazone. Co-administration of icosapent ethyl and rosiglitazone was safe and well tolerated.

Icosapent ethyl: a review of its use in severe hypertriglyceridemia

Icosapent ethyl (Vascepa®) is a high-purity ethyl ester of eicosapentaenoic acid (EPA) that is de-esterified to EPA following oral administration. Both EPA and docosahexaenoic acid (DHA) are long-chain omega-3 fatty acids that have been associated with triglyceride (TG)-lowering. However, DHA has been associated with increased low-density lipoprotein cholesterol (LDL-C) levels. Icosapent ethyl contains ≥96 % of the EPA ethyl ester, does not contain DHA, and is approved in the USA for use as an adjunct to diet to lower TG levels in adult patients with severe (≥500 mg/dL [≥5.65 mmol/L]) hypertriglyceridemia. In a pivotal phase III trial, oral icosapent ethyl 4 g/day significantly decreased the placebo-corrected median TG levels by 33.1 %. It did not increase LDL-C, had favorable effects on other lipid parameters, and had a tolerability profile similar to that of placebo. Therefore, icosapent ethyl is an effective and well-tolerated agent for the treatment of severe hypertriglyceridemia in adults.