Sivelestat sodium CAS NO.201677-61-4

Sivelestat is an acyl enzyme inhibitor of neutrophil elastase, developed as an injectable formulation for the treatment of acute lung injury associated with systemic inflammatory response syndrome. A neutrophil predominant inflammation associated with excessive release of human neutrophil elastase (HNE) from azurophilic granules is capable of damaging both the lung parenchymal cells and the extracellular matrix allowing an alveolar capillary barrier disruption. Sivelestat is a sulfonanilide-containing pivaloyloxy benzene derivative prepared in a three step synthesis. This agent acts as a reversible and selective inhibitor of HNE with an lG.0 value of 0.044 PM. Sivelestat has exhibited potent protective effects against various causes of lung injuries in animal models. In an acid-induced acute lung injury model in conscious hamster, administration of sivelestat for 48 h following HCI instillation, dose-dependently reduced mortality and significantly improved the protein levels in bronchoalveolar lavage fluids and pulmonary artery pressure. In a similar study, the agent inhibited the endotoxin-induced acute lung dysfunctions (marked elevation of pulmonary vascular permeability, leukocyte migration, hemorrhage and parenchymal injury) in different animal species. Moreover, in a cardiopulmonary bypass model in dog, sivelestat ameliorated the respiratory index and interstitial-intra-alveolar edema. Sivelestat has a relatively poor bioavailability, due to an extensive first-pass metabolism and is easily hydrolyzed in vitro to an inactive metabolite. In two animal species, the half-life time was approximately 5-7 min. Clinical trials have shown that treatment with the agent improves respiratory function and facilitates early removal of patients from mechanical ventilation. However, in the last clinical study, conducted by Eli Lilly in patients with acute lung injury, no difference in mortality and safety was seen between sivelestat and placebo.

The synthesis of sivelestat (24) started with the amide formation between 2- nitrobenzoyl chloride (203) and glycine benzyl ester p-tolene sulfonic acid salt (204) in the presence of TEA to give amide 205 in 90% yield. Amide 205 was then reduced with iron power under acidic conditions to give corresponding amine 206 in 81% yield. Alternatively, the mixture of activated Raney nickel, nitro compound 205, acetic acid and 1,3- dimethyl-2-imidazolinone (DMI) under 25 atmospheric pressure of hydrogen at 40oC in an autoclave can give the same free amine 206 in 88% yield. Free amine 206 was treated with p-pivaloyloxybenzenesulfonyl chloride (207) in pyridine to yield sulfonamide 208 in 87% yield. Benzyl ester 208 was converted to its free carboxylic acid under hydrogenation, and the carboxylic acid was subsequently basified to give sivelestat sodium