Sulfonamides: a patent review (2008-2012)

Introduction: The primary sulfonamide moiety is present in many clinically used drugs, such as diuretics (furosemide, indapamide, chlorthalidone, thiazides); carbonic anhydrase (CA) inhibitors (CAIs) (including acetazolamide, dichlorophenamide, dorzolamide and brinzolamide); antiepileptics (zonisamide and sulthiame); the antipsychotic sulpiride and the cycloxygenase 2 (COX2) inhibitors celecoxib and valdecoxib. Recently, novel drugs have been launched, such as apricoxib and pazopanib, which also incorporate this group. Areas covered: The article presents the main classes of sulfonamides investigated between 2008 and 2012. Specifically, the authors review the scientific and patent literature on CAIs, COX2 inhibitors, pazopanib and its congeners, which are multi-targeted receptor tyrosine kinase inhibitor of VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-a/beta, and c-kit. Expert opinion: Most patents deal with sulfonamide CAIs incorporating NO-donating moieties as antiglaucoma agents, or with compounds targeting the tumor-associated isoforms CA IX/XII. The antidandruff actions of sulphonamides, which inhibit yeast CAs, were also claimed. Apricoxib (a COX2 inhibitor) and pazopanib, a tyrosine kinase inhibitor, show significant antitumor activity and several patents deal with these drugs. There is a constant need of novel sulfonamides to act as selective antiglaucoma drugs (targeting CA II), as antitumor agents/diagnostic tools (targeting CA IX/XII), and to treat and diagnose other disease. This privileged structural motif is likely to be present in other drugs in the future.