Neutralization of EP217609, a new dual-action FIIa/FXa anticoagulant, by its specific antidote avidin: a phase I study.

INTRODUCTION: EP217609 is a representative of a new class of synthetic parenteral anticoagulants with a dual mechanism of action. It combines in a single molecule a direct thrombin inhibitor and an indirect factor Xa inhibitor. EP217609 can be neutralized by a specific antidote avidin, which binds to the biotin moiety of EP217609. PURPOSE: The primary objective was to assess the neutralization of EP217609 by avidin in healthy subjects. Secondary objectives were to define the optimal avidin monomer/EP217609 molar ratio to achieve an adequate neutralization of EP217609 and to assess the safety and tolerability of EP217609 and avidin. METHODS: Healthy subjects (n = 36) were randomized to a 3 by 3 replicated Latin square design between 3 EP217609 doses (4, 8, 12 mg) and 3 avidin monomer/EP217609 molar ratios (1:1; 2:1; 3:1). EP217609 was administered as a single intravenous bolus, and avidin as a 30-min intravenous infusion, starting 90 min after EP217609 administration. RESULTS: Overall, EP217609 and avidin were well tolerated. One subject experienced a benign and transient typical pseudo-allergic reaction. The administration of EP217609 resulted in dose-dependent increases in pharmacodynamic markers. Avidin triggered a rapid and irreversible neutralization of EP217609 without rebound effect. Adequate neutralization of the anticoagulant activity was achieved with both 2:1 and 3:1 avidin monomer/EP217609 molar ratios. All safety parameters did not show any treatment-emergent clinically relevant changes or abnormalities in any dose group. CONCLUSIONS: These results will allow further investigation in patients requiring a neutralizable anticoagulant as those undergoing cardiac surgery. STUDY REGISTRATION: EudraCT number 2010-020216-10.

First in man study of EP217609, a new long-acting, neutralisable parenteral antithrombotic with a dual mechanism of action.

UNLABELLED: EP217609 is a parenteral antithrombotic compound combining in one molecule an indirect anti-factor Xa inhibitor, a direct thrombin active site inhibitor and a biotin moiety. AIMS: The aim of the study is to investigate the safety, pharmacokinetics and pharmacodynamics of single ascending intravenous doses of EP217609. METHODS: In this randomised double-blind placebo-controlled study, healthy male subjects were administered intravenously single ascending doses (1, 3 or 10 mg) of EP217609 or placebo. Each treatment group consisted of 10 subjects of whom 8 received EP217609 and 2 received placebo. RESULTS AND CONCLUSIONS: All doses of EP217609 were well tolerated. A total of five treatment-emergent adverse events were reported, all considered unrelated, but no bleedings or other significant adverse events occurred during this study. In both plasma and urine, there was a strong correlation between EP217609 concentrations as measured by anti-factor IIa and Xa specific bioassays indicating that the two pharmacological activities of EP217609 did not dissociate in vivo. EP217609 pharmacokinetics were dose proportional and characterised by a low clearance, a small volume of distribution and a terminal half-life of 20.4 h. The long half-life was reflected in long-lasting, dose-dependent effects on activated and ecarin clotting time, thrombin and prothrombin time, activated partial thromboplastin time, thrombin generation time and anti-factor Xa activity. Pharmacokinetic/pharmacodynamic modelling indicated that the concentration of EP217609 producing 50 % of the pharmacodynamic effect was 3400 and 2210 ng/mL for activated clotting time and anti-factor Xa activity, respectively. These results warranted further clinical development of EP217609. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: • There is a limited number of neutralisable anticoagulants, particularly when rapid neutralisation is required. • Synthetic anti-Xa compounds have predictable pharmacokinetic profiles. However, problems with thrombin rebound remain because of the inability to inhibit clot-bound thrombin. WHAT THIS STUDY ADDS: • This manuscript provides a comprehensive investigation of the pharmacokinetics, pharmacodynamics and safety of EP217609, and the results were the basis of future clinical studies in both healthy subjects and patients. • The pharmacokinetic/pharmacodynamic modelling provided information for dose selection in such future studies.

In vitro and in vivo pharmacokinetic characteristics of clazosentan, an intravenous endothelin receptor antagonist, in humans.

OBJECTIVE: In this study, the distribution, metabolism and excretion of the endothelin receptor antagonist clazosentan were investigated. SUBJECTS AND METHODS: 4 healthy male subjects received an intravenous 3-h infusion at a rate of 0.2 mg/kg/h of 14C-labeled clazosentan and blood, urine and feces samples were collected for a period of 8 days. Experiments were performed to investigate the plasma protein binding, the binding to red blood cells and the inhibition potential of cytochrome P450 isoenzymes of clazosentan. RESULTS: Clazosentan was mainly excreted unchanged into feces whereas about 15% of the radioactive dose was recovered in urine. No metabolites representing more than 5% of total radioactivity were identified. No relevant inhibition of the human cytochrome P450 isoenzymes, 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4, was observed in vitro at clazosentan concentrations largely exceeding those observed in clinical trials. In human blood, clazosentan was highly bound to plasma proteins and did hardly penetrate into red blood cells. CONCLUSION: The primary route of excretion of clazosentan was via the feces, mainly as unchanged drug.

Inhibitory and inductive effects of rifampin on the pharmacokinetics of bosentan in healthy subjects.

This study was conducted to investigate the effect of rifampin on the pharmacokinetics of bosentan. Healthy male subjects received bosentan 125 mg b.i.d. for 6.5 days in the presence or absence of rifampin 600 mg once a day. In vitro experiments were performed to investigate the effect of rifampin on the uptake of bosentan into Chinese hamster ovary cells expressing the human organic anion-transporting polypeptide (OATP)1B1, -1B3, and -2B1. Following the first concomitant administration, there was a fivefold increase in bosentan trough concentrations. At steady state, concomitant rifampin significantly decreased exposure to bosentan by 58%. Rifampin potently inhibited the uptake of bosentan into cells expressing human OATP1B1 and -1B3. Rifampin decreased the exposure to bosentan consistent with its known cytochrome P450 enzyme-inductive properties. The initial increase in bosentan concentrations can be explained by an inhibitory effect of rifampin on hepatic drug transporters.

Pharmacokinetic interaction between bosentan and the oral contraceptives norethisterone and ethinyl estradiol.

OBJECTIVE: Bosentan has been shown in vitro and in vivo to induce the cytochrome P450 enzymes CYP2C9 and CYP3A4. The present study was conducted to investigate the effect of bosentan on the pharmacokinetics of a combined oral contraceptive. SUBJECTS AND METHODS: In a randomized, 2-way crossover study, 20 healthy female subjects received Treatments A and B. Treatment A consisted of a single dose of OrthoNovum containing 1 mg norethisterone (norethindrone) and 35 microg ethinyl estradiol. Treatment B consisted of bosentan, 125 mg b.i.d. for 7 days plus concomitant norethisterone and ethinyl estradiol on Day 7. Plasma concentrations of norethisterone and ethinyl estradiol were measured on days of oral contraceptive administration. RESULTS: In the absence of bosentan, the pharmacokinetics of norethisterone and ethinyl estradiol were characterized by Cmax and AUC0-infinity values (95% CI) of 9.8 (8.1, 11.9) ng/ml and 72.9 (57.0, 93.1) ng x h/ml, and 53.0 (47.0, 59.9) pg/ml and 758 (655, 878) pg x h/ml, respectively. Concomitant bosentan did not affect the Cmax but significantly decreased the AUC of norethisterone and ethinyl estradiol by 13.7% (-23.5, -2.6) and 31.0% (-40.5,-20.2), respectively. The maximum decrease in AUC of norethisterone and ethinyl estradiol in an individual subject was 56% and 66%, respectively. CONCLUSIONS: Bosentan decreases the AUC of norethisterone and ethinyl estradiol in healthy female subjects. In patients treated with bosentan, reduced efficacy of hormonal contraceptives should be considered.

Effect of severe renal impairment on the pharmacokinetics and tolerability of the parenteral endothelin antagonist tezosentan.

BACKGROUND: Tezosentan, an endothelin receptor antagonist, is under development for the treatment of acute heart failure. Impaired renal function is a frequent comorbidity in these patients. OBJECTIVE: To assess the pharmacokinetics and tolerability of tezosentan in 8 patients with severe renal impairment (creatinine clearance < 30 ml/min) compared to 8 healthy subjects. METHODS: Tezosentan was infused at a rate of 100 mg/h for 1 h. Blood and urine samples were collected for pharmacokinetic determinations. Vital signs, ECG, adverse events and clinical laboratory parameters were monitored to assess tolerability. RESULTS: The mean (95% confidence interval) volume of distribution and clearance of tezosentan in renal patients were 15 (13, 18) l and 42 (34, 52) l/h, respectively, and did not differ significantly from the values of 18 (15, 20) l and 36 (29, 44) l/h found in healthy subjects. In patients, the renal excretion of tezosentan was impaired. Tezosentan caused a decrease in blood pressure and was well tolerated in both groups. CONCLUSION: No clinically relevant effects of severe renal impairment on the pharmacokinetics and tolerability of tezosentan were found. Therefore, no dose adjustment oftezosentan is deemed necessary in patients with any grade of renal impairment.

Influence of severe renal dysfunction on the pharmacokinetics and metabolism of bosentan, a dual endothelin receptor antagonist.

BACKGROUND: One of the potential indications of bosentan, a dual endothelin receptor antagonist, is chronic heart failure. Patients with chronic heart failure frequently also suffer from impaired renal function. OBJECTIVE: To explore the influence of severe renal dysfunction on the pharmacokinetics and metabolism of bosentan in a monocenter, open label, parallel group study. METHODS: Eight renal patients with creatinine clearance 17 - 27 ml/min and 8 healthy subjects (creatinine clearance 99 - 135 ml/min) received a single oral dose of 125 mg bosentan and plasma samples drawn for up to 36 hours after administration were analyzed for bosentan and 3 metabolites. RESULTS: The pharmacokinetic parameters of bosentan did not differ significantly between the study groups: geometric means (95% confidence interval) for Cmax were 1.8 (1.2 - 2.8) and 1.1 microg/ml (0.74 - 1.7), and for AUC0-infinity 7.2 (5.1 - 10.4) and 6.4 (3.4 - 11.2) microg x h/ml in healthy subjects and renal patients, respectively. Levels of the 3 CYP2C9- and CYP3A4-derived metabolites increased approximately 2-fold in renal patients, both in absolute terms and in relation to the parent compound. In renal patients, the exposure to Ro 48-5033, the only pharmacologically active metabolite, was 13% of that to bosentan. CONCLUSION: Severe renal dysfunction did not affect the pharmacokinetics of bosentan to a clinically relevant extent and, therefore, no dose adjustments are deemed necessary in patients with any grade of renal insufficiency.

EP42675, a synthetic parenteral dual-action anticoagulant: pharmacokinetics, pharmacodynamics, and absence of interactions with antiplatelet drugs.

BACKGROUND: EP42675 is a first-in-class, synthetic, parenteral, anticoagulant combining in a single molecule a direct thrombin inhibitor and an indirect factor Xa(FXa) inhibitor. OBJECTIVES: To investigate the safety, pharmacokinetics, and pharmacodynamics of EP42675 and its interaction with aspirin, clopidogrel, and unfractionated heparin (UFH). SUBJECTS AND METHODS: In study 1, healthy male subjects were administered intravenously single-ascending doses (1-10 mg) of EP42675 or placebo. In study 2, healthy male subjects were administered intravenously a single dose of 5 mg EP42675 on day 1 followed by oral administration of aspirin (100 mg) and clopidogrel (75 mg) once daily from day 8 to 21. On day 15, a second dose of 5 mg EP42675 was administered, and subjects were then randomized to receive a single dose of UFH (30 or 60 IU kg(-1) ) or placebo. RESULTS AND CONCLUSIONS: Mild bleedings were the only drug-related adverse events. EP42675 pharmacokinetics were dose-proportional and characterized by a low clearance, a small volume of distribution, a long terminal half-life. EP42675 pharmacodynamics were characterized by a long-lasting, dose-dependent increase in activated clotting time, ecarin clotting time, thrombin time, anti-FXa activity, activated partial thromboplastin time, prothrombin time, and a decrease in endogenous thrombin potential, measured by a thrombin generation test. Dose-dependent additive effects were seen with UFH on coagulation tests. EP42675 had no additive effect on the inhibition of platelet aggregation induced by aspirin and clopidogrel. These results warrant further clinical development of this new class of anticoagulant.

In vivo and in vitro disposition profile of tezosentan, an intravenous dual endothelin receptor antagonist, in humans.

1. The plasma concentration-time profile of the (14)C-labelled endothelin receptor antagonist tezosentan in healthy male volunteers after a 1-h infusion at 100 mg h(-1) followed a biphasic decline with half-lives of 3-5 min for the initial disposition phase and approximately 4 h for the terminal phase. 2. Tezosentan was predominantly excreted unchanged into faeces, whereas less than 5% of the dose was excreted as unchanged drug in urine. Two isomeric, hydroxylated metabolites (M1, M2) were detected in faeces representing 2-5% of the total radioactivity. 3. In vitro, with human liver microsomes and primary hepatocytes, tezosentan was metabolized at very low rates. Upon prolonged incubation with human hepatocytes for 24 h, formation of the hydroxylated metabolite M1 and a glucuronic acid conjugate, M3, was observed. 4. No relevant inhibition of the human cytochrome P450 (CYP) forms, CYP1A2, 2C9, 2C19, 2D6 and 3A4, was observed in vitro at tezosentan concentrations largely exceeding those observed in clinical trials. 5. In human blood, tezosentan was highly bound to plasma proteins, mainly albumin, and hardly penetrated into red blood cells.