A multiplex DNA microarray chip was developed for simultaneous identification of nine genetically modified organisms (GMOs), five plant species and three GMO screening elements, i.e. the 35S promoter, the nos terminator and the nptII gene. The chips also include several controls, such as that for the possible presence of CaMV. The on-chip detection was performed directly with PCR amplified products. Particular emphasis was placed on the reduction of the number of PCR reactions required and on the number of primers present per amplification tube. The targets were biotin labelled and the arrays were detected using a colorimetric methodology. Specificity was provided by specific capture probes designed for each GMO and for the common screening elements. The sensitivity of the assay was tested by experiments carried out in five different laboratories. The limit of detection was lower than 0.3% GMO for all tests and in general around 0.1% for most GMOs. The chip detection system complies with the requirements of current EU regulations and other countries where thresholds are established for the labelling of GMO.
Macitentan is a dual endothelin receptor antagonist under phase 3 investigation in pulmonary arterial hypertension. We investigated the effect of cyclosporine (Cs) and rifampin on the pharmacokinetics of macitentan and its metabolites ACT-132577 and ACT-373898 in healthy male subjects. In addition, in vitro studies were performed to investigate interactions between macitentan and its active metabolite ACT-132577 with human organic anion-transporting polypeptides (OATPs). The clinical study (AC-055-111) was conducted as a two-part, one-sequence, crossover study. Ten subjects in each part received multiple-dose macitentan followed by multiple-dose co-administration of Cs (part A) or rifampin (part B). In the presence of Cs, steady-state area under the plasma concentration–time profiles during a dose interval (AUCτ) for macitentan and ACT-373898 increased 10% and 7%, respectively, and decreased 3% for ACT-132577. Steady-state AUCτ of macitentan and ACT-373898 in the presence of rifampin decreased 79% and 64%, respectively. For ACT-132577, no relevant difference in AUCτ between the two treatments was observed. Macitentan co-administered with Cs or rifampin was well tolerated. The complementary in vitro studies demonstrated no marked differences in uptake rates of macitentan and ACT-132577 between the wild-type and OATP over-expressing cells over the concentration range tested. Concomitant treatment with Cs did not have any clinically relevant effect on the exposure to macitentan or its metabolites, at steady-state. Concomitant treatment with rifampin reduced significantly the exposure to macitentan and its metabolite ACT-373898 at steady-state but did not affect the exposure to the active metabolite ACT-132577 to a clinically relevant extent.
Macitentan is a tissue-targeting, dual endothelin receptor antagonist, currently under phase 3 investigation in pulmonary arterial hypertension. In this study the disposition and metabolism of macitentan were investigated following administration of a single oral 10 mg dose of (14)C-macitentan to six healthy male subjects. The total radioactivity in matrices was determined using liquid scintillation counting. The proposed structure of metabolites was based on mass spectrometry characteristics and, when available, confirmed by comparison with reference compounds. Mean (± SD) cumulative recovery of radioactivity from faeces and urine was 73.6% (± 6.2%) of the administered radioactive dose, with 49.7% (± 3.9%) cumulative recovery from urine, and 23.9% (± 4.8%) from faeces. In plasma, in addition to parent macitentan, ACT-132577, a pharmacologically active metabolite elicited by oxidative depropylation and the carboxylic acid metabolite ACT-373898 were identified. In urine, four entities were identified, with the hydrolysis product of ACT-373898 as the most abundant one. In faeces, five entities were identified, with the hydrolysis product of macitentan and ACT-132577 as the most abundant one. Concentrations of total radioactivity in whole blood were lower compared to plasma, which indicates that macitentan and its metabolites poorly bind to or penetrate into erythrocytes.
Objective: The objective of this study was to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of selexipag, an orally available selective prostacyclin receptor agonist, in development for pulmonary arterial hypertension in healthy subjects. Methods: This was a double-blind, placebo-controlled, randomised, multiple-ascending-dose, up-titration study. Male subjects received increasing oral doses of selexipag (400-1,800 µg; n = 12) or placebo (n = 4) twice daily for 3 days each, using incremental steps of 200 µg between each dose level. Standard safety and tolerability data were collected. Blood samples were taken to assess the pharmacokinetics of selexipag and its active metabolite ACT-333679 and possible effects on platelet aggregation. Results: Dose levels of selexipag up to 1,600 μg were well tolerated and this dose was identified as the maximum tolerated dose. Plasma exposure to ACT-333679 was approximately 4 times higher than that to selexipag. Steady-state conditions for both compounds were reached on day 3 of each dose level, and no accumulation of selexipag or ACT-333679 was observed. Based on the area under the curve and the maximum plasma concentration, the pharmacokinetics of selexipag and ACT-333679 were dose proportional. At the highest dose level, the geometric mean terminal half-life of selexipag and ACT-333679 was 1.4 and 8.7 h, respectively. The observed effects on platelet aggregation were variable without obvious drug- or dose-dependent pattern. Conclusions: Oral administration of increasing doses of selexipag was well tolerated. The present results support the conduct of future clinical trials.
PurposeTargeting the prostacyclin pathway is an effective treatment option for pulmonary arterial hypertension (PAH). Patients with PAH have a deficiency of prostacyclin and prostacyclin synthase. Selexipag is an orally available and selective prostacyclin receptor (IP receptor) agonist. Selexipag is hydrolyzed to its active metabolite ACT-333679, also a selective and potent agonist at the IP receptor.MethodsIn this phase I study the pharmacokinetics (PK) and tolerability of single and multiple ascending doses of selexipag were investigated in a double-blind, placebo-controlled manner in 64 healthy male subjects. An additional group of 12 subjects received an open-label dose of selexipag 400 μg in the fasted condition and after a meal.ResultsMaximum plasma concentrations of selexipag and ACT-333679 were reached within 2.5 and 4 h, respectively, with mean half-lives of 0.7–2.3 and 9.4–14.22 h. In the presence of food, exposure to ACT-333679 was decreased by 27 %. The most frequent adverse event was headache. Selexipag was well tolerated up to a single dose of 400 μg and multiple doses of 600 μg following an up-titration step. No relevant treatment-related effects on vital signs, clinical laboratory, and electrocardiogram (ECG) parameters were detected.ConclusionSelexipag exhibits a good tolerability profile and PK properties that warrant further investigation.
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