SPL Set ID: 39b2a85f-4322-42d4-b420-1b1d52569143

Bosentan, an endothelin receptor antagonist that belongs to a class of highly substituted pyrimidine derivatives, with no chiral centers. It is designated chemically as 4-tert-butyl-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-[2,2´]-bipyrimidin-4-yl]-benzenesulfonamide monohydrate and has the following structural formula: C 27 H 29 N 5 O 6 S•H 2 O M.W. 569.64 Bosentan is a white to yellowish powder. It is poorly soluble in water (1.0 mg/100 mL) and in aqueous solutions at low pH (0.1 mg/100 mL at pH 1.1 and 4.0; 0.2 mg/100 mL at pH 5.0). Solubility increases at higher pH values (43 mg/100 mL at pH 7.5). In the solid state, bosentan is very stable, is not hygroscopic and is not light sensitive. Bosentan is available as 62.5 mg and 125 mg film-coated tablets for oral administration, and contains the following excipients: corn starch, ethyl cellulose, glyceryl behenate, hypromellose, iron oxide red, iron oxide yellow, magnesium stearate, pregelatinized corn starch, povidone K90, sodium starch glycolate, titanium dioxide and triacetin. Each bosentan 62.5 mg tablet contains 64.541 mg of bosentan monohydrate, equivalent to 62.5 mg of bosentan base. Each bosentan 125 mg tablet contains 129.082 mg of bosentan monohydrate, equivalent to 125 mg of bosentan base. 1