Ramatroban: PGD2 Receptor Antgonist (Highly Selective) 3mg/ml, 60ml
Ramatroban or Baynas, formerly callled BAY u3405, is a highly selective prostaglandin D2 (PGD2) or CRTH2/GPR-44 receptor antagonist. Ramatroban is used for treating allergies (orally) and may be used in the future to treat baldness (topically). Ramatroban is highly selective for blocking prostaglandin D2 and 15d-PGJ2 (the most potent known physiological ligand for the PGD2 receptor) without interfering with activity of PGF2a or PGE2, making it an ideal compound for studying the different bound effects of prostaglandin receptor types on diseases or disorders like baldness, allergy, and inflammation. Following the landmark Garza and Cotsarelis study (2012) linking prostaglandin D2 with male pattern baldness or androgenic alopecia (sometimes called androgenetic alopecia), demand for PGD2 inhibitors to be developed and put through the clinical trial process as candidates for a baldness cure has developed; ramatroban, with a history of human use and clinical trials for allergies, plus its highly selective nature, may be a candidate for development.
Ramatroban’s mechanism of action to potentially treat baldness, and to treat allergies, is to block activity at the PGD2 (CRTH2/GPR-44) receptor. Ramatroban is an effective PGD2 antagonist without interfering with the activities of other prostaglandins, which is the most direct mechanism of disrupting the PGD2 pathway as compared to prostaglandin D synthase (PGD-S) inhibition or reducing levels of “upstream” compounds such as androgens which may contribute to elevated levels of PGD2.
A 1% DMSO solution of ramatroban was found to totally inhibit PGD2 and related activity at the CRTH2 receptor; the authors (Mathiesen et al, 2005) identified ramatroban as a suitable reference compound to further distinguish and characterize the differential effects of activity at prostaglandin receptors.
The crossover or overlap between inhibiting the allergic response (for which ramatroban is approved in some regions) and potentially using the PGD2 pathway to prevent or reverse baldness (a potential future development milestone) is notable. PGD2, 15d-PGJ2 (fifteen times more powerful agonist compared to PGD2), and indomethacin all bind to the same site, and this site is the CRTH2/GPR-44 (PGD2) receptor, which is also the same site identified by Cotsarelis and Garza (2012) in being a key site apparently involved in the etiology and progression of male pattern baldness, or at least able to induce baldness.
 Sugimoto H, Shichijo M, Okano M, Bacon KB. CRTH2-specific binding characteristics of [3H]ramatroban and its effects on PGD2-, 15-deoxy-Delta12, 14-PGJ2- and indomethacin-induced agonist responses. Eur J Pharmacol. 2005 Nov 7;524 (1-3):30-7 16256979
 Mathiesen JM, Ulven T, Martini L, et al. Identification of Indole Derivatives Exclusively Interfering with a G Protein-Independent Signaling Pathway of the Prostaglandin D2 Receptor CRTH2. Kostenis Mol Pharmacol 68:393–402, 2005.
 Garza LA, Liu Y, Yang Z, Alagesan B, Lawson JA, Norberg SM, Loy DE, Zhao T, Blatt HB, Stanton DC, Carrasco L, Ahluwalia G, Fischer SM, FitzGerald GA, Cotsarelis G. Prostaglandin D2 inhibits hair growth and is elevated in bald scalp of men with androgenetic alopecia. Sci Transl Med. 2012 Mar 21;4(126):126ra34.
 Trüeb RM. Molecular mechanisms of androgenetic alopecia. Exp Gerontol. 2002 Aug-Sep;37(8-9):981-90.