Absorption, distribution, metabolism, and excretion of macitentan, a dual endothelin receptor antagonist, in humans.
Summary of "Absorption, distribution, metabolism, and excretion of macitentan, a dual endothelin receptor antagonist, in humans."
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.
Clinical Pharmacology , Allschwil , Switzerland.
This article was published in the following journal.
Name: Xenobiotica; the fate of foreign compounds in biological systems
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22458347
- DOI: http://dx.doi.org/10.3109/00498254.2012.664665
Medical and Biotech [MESH] Definitions
Receptor, Endothelin A
A subtype of endothelin receptor found predominantly in the VASCULAR SMOOTH MUSCLE. It has a high affinity for ENDOTHELIN-1 and ENDOTHELIN-2.
Receptor, Endothelin B
A subtype of endothelin receptor found predominantly in the KIDNEY. It may play a role in reducing systemic ENDOTHELIN levels.
Dynamic and kinetic mechanisms of exogenous chemical and drug ABSORPTION; BIOLOGICAL TRANSPORT; TISSUE DISTRIBUTION; BIOTRANSFORMATION; elimination; and TOXICOLOGY as a function of dosage, and rate of METABOLISM. It includes toxicokinetics, the pharmacokinetic mechanism of the toxic effects of a substance. ADME and ADMET are short-hand abbreviations for absorption, distribution, metabolism, elimination and toxicology.
A 21-amino acid peptide produced predominantly within the kidney and intestine, with smaller amounts produced in the myocardium, placenta, and uterus, but the cells of origin are not clear. Endothelin-2 has no unique physiologic functions, as compared with endothelin-1. (N Eng J Med 1995;333(6):356-63)
21-Amino-acid peptides produced by vascular endothelial cells and functioning as potent vasoconstrictors. The endothelin family consists of three members, ENDOTHELIN-1; ENDOTHELIN-2; and ENDOTHELIN-3. All three peptides contain 21 amino acids, but vary in amino acid composition. The three peptides produce vasoconstrictor and pressor responses in various parts of the body. However, the quantitative profiles of the pharmacological activities are considerably different among the three isopeptides.
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