Ramatroban, originally developed for the treatment of cardiovascular pathologies as
thromboembolism, was finally introduced in Japan for the treatment of allergic rhinitis. It is
a (3R)-enantiomer that can be synthesized in 5 steps from 3-oxo-1,2,3,4-
tetrahydrocarbazole by stereoselective reductive amination, using S-phenethylamine as
the chiral source, followed by hydrogenolysis, sulfonylation and finally 2-step Ncarboxyethylation.
Ramatroban is a potent antagonist of prostaglandin receptors (PGD2,
PGH2) and thromboxane receptors (TxA2); accordingly, it blocks the contractions induced
by thromboxane or TxA2-mimetics in animal and human airway smooth muscle. It also
prevents, when administered i.v., p.o. or by aerosol, bronchoconstriction induced by PGD2
or antigen. In animal models of nasal allergy, ramatroban inhibits antigen-induced
neutrophil infiltration into nasal mucosa and also inhibits nasal symptoms. In several
species including humans, it is well-absorbed, extensively protein-bound (>95%) and
eliminated mainly as a glucuro-conjugate; in man, its terminal half-life is 2 to 3 hours.
A thromboxane receptor antagonist for use in the treatment of coronary artery disease.
ChEBI: Ramatroban is an organic molecular entity.
Potent dual antagonist of TP/DP 2 (CRTH2) prostanoid receptors (K i values are 4.3, 4.5 and > 10000 nM for hDP 2 , hTP and hDP 1 receptors respectively). Suppresses PGD 2 -induced migration of human eosinophils (IC 50 = 170 nM).
bay u3405 showed significant inhibitory effects on the binding of 3h-labeled pgd2 to crth2, albeit with much lower potency. bay u3405 and indomethacin also inhibited pgd2-induced ca2+ mobilization in crth2 transfectants to almost the same extent. however, indomethacin but not bay u3405 was confirmed as an agonist of ca2+ mobilization at concentrations greater than 10 nm [1].
for rat with splanchnic artery occlusion shock, administration of bay u3405 at 30 mg/kg i.v. could significantly increase the survival time and survival rate, improve mean arterial blood pressure, reduce the plasma levels of myocardial depressant factor, partially restore macrophage phagocytosis and lower mpo activity in both the ileum and the lung [2].
[1] sugimoto, h. ,shichijo, m.,iino, t., et al. an orally bioavailable small molecule antagonist of crth2, ramatroban (bay u3405), inhibits prostaglandin d2-induced eosinophil migration in vitro. journal of pharmacology and experimental therapeutics 305, 347-352 (2003).
[2] canale p, squadrito f, altavilla d, ioculano m, campo gm, squadrito g, urna g, sardella a, caputi ap. beneficial effects of bay u3405, a novel thromboxane a2 receptor antagonist, in splanchnic artery occlusion shock. pharmacology. 1994 dec;49(6):376-85.
[3] aizawa h, shigyo m, nogami h, hirose t, hara n. bay u3405, a thromboxane a2 antagonist, reduces bronchial hyperresponsiveness in asthmatics. chest. 1996 feb;109(2):338-42.
