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ABSTRACT: What is known: Bosentan is a dual endothelin receptor antagonist approved for the treatment of pulmonary arterial hypertension (PAH). Since bosentan is frequently used to treat pediatric PAH patients, a pediatric formulation was developed. Aim: To evaluate the pharmacokinetic properties of bosentan and its active metabolite, Ro 48-5033, of the quadrisected, dispersible pediatric vs. the adult tablet after single-dose administration to healthy subjects. Secondary objectives of the study were to compare the pharmacokinetics of two inactive metabolites and the safety of both formulations. Materials and methods: In this open-label, two-way crossover study, subjects (20 - 43 years) were randomized to receive single oral doses of 62.5 mg of bosentan as 1 adult tablet and 64 mg as 2 pediatric tablets of 32 mg. Blood samples were drawn over a 48-hour period to measure bosentan and its metabolites. Results: 16 subjects were enrolled and completed the study. Following treatment with the pediatric formulation, values for Cmax and AUC0-∞ of bosentan were lower than with the adult formulation with geometric mean ratios (90% confidence interval) of 0.82 (0.65, 1.04) and 0.87 (0.78, 0.97), respectively. Similar results were obtained for the primary active metabolite Ro 48-5033. Both treatments were well tolerated. What is new and conclusion: Although the 90% confidence intervals of the geometric mean ratios of Cmax and AUC0-∞ were not entirely within the conventional bioequivalence range (0.80 - 1.25), no clinically relevant effect of formulation on the pharmacokinetics of bosentan and Ro 48-5033 was detected. Both formulations were well tolerated.
International journal of clinical pharmacology and therapeutics 04/2013; · 1.18 Impact Factor
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ABSTRACT: BACKGROUND: Epoprostenol sodium for injection is approved for the treatment of severe cases of primary pulmonary arterial hypertension. Currently, there are 3 approved formulations of this drug containing the same active ingredient (epoprostenol sodium) but differing with regard to excipients. When compared with epoprostenol sodium formulated with glycine-mannitol (epoprostenol GM), 2 new formulations of epoprostenol sodium, one formulated with arginine-mannitol (epoprostenol AM) and one formulated with arginine-sucrose (epoprostenol AS), have improved stability after reconstitution and dilution. The biocomparability of epoprostenol AM and epoprostenol GM, with regard to pharmacokinetic (PK), pharmacodynamic (PD), safety, and tolerability profiles, has been shown previously. OBJECTIVE: This study compared PK, PD, safety, and tolerability profiles of the 3 different formulations of epoprostenol sodium for injection. METHODS: This was a prospective, single-center, open-label, 2-period, 2-treatment, randomized, crossover, ascending dose study in 2 parts. Twenty healthy men in part 1 and 20 different individuals in part 2 received epoprostenol AM and epoprostenol AS and epoprostenol GM and epoprostenol AS, respectively, in a crossover fashion, as sequential IV infusions of 2, 4, 6, and 8 ng/kg/min for 2 hours each. In each part, the PK profile of epoprostenol was characterized via analysis of the concentration-time profiles of its 2 primary metabolites: 6-keto-prostacyclin F1α and 6,15-diketo-13,14-dihydro-prostacyclin F1α. The effect of the formulations was assessed using the 90% CI of the geometric mean ratio calculated for the exposure PK parameters. The PD variables cardiac output, cardiac index, and heart rate were assessed using echocardiography. Adverse events were recorded through the study. RESULTS: The plasma concentration versus time curves of epoprostenol AM and epoprostenol AS in part 1 and epoprostenol GM and epoprostenol AS in part 2 were similar in shape and almost superimposable. For each study part, the 90% CIs of ratios of geometric means for AUC0-∞ of the assessed epoprostenol formulations were within the range for bioequivalence (0.8-1.25). The increases in cardiac output, cardiac index, and heart rate resulting from infusion with epoprostenol sodium were comparable between all formulations, with maximum values attained after 8 hours. Almost all study participants reported at least one treatment-emergent adverse event, the most common being headache, which was reported in 80% to 85% of study participants. CONCLUSIONS: Overall, the PK, PD, safety, and tolerability profiles of the 3 formulations of epoprostenol sodium for injection are comparable and meet the criteria of bioequivalence. Australian New Zealand Clinical Trials Registry identifier: ACTRN12612001086853.
Clinical Therapeutics 03/2013; · 2.32 Impact Factor
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ABSTRACT: AIMS: Report the first thorough characterization of the pharmacokinetics (PK) and pharmacodynamics (PD) of epoprostenol in an integrated manner. METHODS: Twenty healthy male subjects received two formulations of intravenous epoprostenol, in a cross-over design, in sequential infusions of 2, 4, 6, and 8 ng/kg/min for 2 h each. A sensitive assay was developed which allowed accurate PK characterisation of epoprostenol via analysis of the concentration-time profiles of its 2 primary metabolites, 6 keto-prostacyclin F1α and 6,15-diketo-13,14-dihydro-prostacyclin F1α. PD parameters included cardiac output (CO), cardiac index (CIn), and heart rate (HR). RESULTS: The pharmacokinetics of epoprostenol deviated slightly from dose-proportionality, probably due to a food effect. After infusion of the two formulations of epoprostenol, the t(1/2 ) values expressed as geometric mean (95% confidence interval) were 0.25h (0.14-0.46) and 0.22h (0.13-0.38) for 6 keto-prostacyclin F1α, and 0.32h (0.22-0.45) and 0.34h (0.26-0.46) for 6,15-diketo-13,14-dihydro-prostacyclin F1α. A single compartment infusion model with first order elimination adequately described the PK of 6 keto-prostacyclin F1α. This model also characterised the food effect. Stepwise infusions with epoprostenol resulted in a progressive increase in CO, CIn, and HR. CONCLUSIONS: Of the two metabolites analysed, the appearance of 6-keto-prostacyclin F1α in plasma was more closely associated with the haemodynamic effects of intravenous epoprostenol. PK and PD profiles showed that CIn relates proportionally and linearly to the plasma concentrations of 6-keto-prostacyclin F1α. These results suggest that 6-keto-prostacyclin F1α is a suitable surrogate marker of plasma levels of epoprostenol. © 2012 Actelion Pharmaceuticals Ltd. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.
British Journal of Clinical Pharmacology 04/2012; · 2.96 Impact Factor
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ABSTRACT: To evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of escalating single oral doses of ACT-077825, a novel orally active renin inhibitor, in healthy male subjects.
In this single-center, double-blind, placebo- and active-controlled (with enalapril) randomized study, 70 subjects received a single dose of ACT-077825 (1-1,000 mg), placebo, or enalapril 20 mg under fasted conditions. The main pharmacokinetic endpoints were area under the plasma ACT-077825 concentration-time curve from time zero to infinity and the terminal half-life (t(1/2)). The pharmacodynamic endpoints included immunoactive active renin (iAR) plasma concentrations and plasma renin activity (PRA). Standard laboratory and safety data were collected.
Of the few adverse events reported, diarrhea and headache were the most frequent. The pharmacokinetics of ACT-077825 were dose-proportional in the dose range 100 to 1,000 mg. Terminal t(1/2), best characterized following a dose of 1,000 mg, was 41.6 h and t(max) 4-5 h post-dose. ACT-077825 dose-dependently increased iAR and decreased PRA, effects that were associated with a decrease in blood pressure at 1,000 mg, similar to following treatment with enalapril.
The results provide evidence that ACT-077825, with a pharmacokinetic profile consistent with a once-a-day dosing regimen, may represent an effective antihypertensive agent and pave the way toward a multiple-ascending dose study.
European Journal of Clinical Pharmacology 03/2012; 68(9):1257-66. · 2.85 Impact Factor
