The present review sets out to discuss recent developments and prospects of absorption promoters and absorption modulator systems being developed commercially by companies specialising in nasal drug delivery of normal small molecular weight drugs and biological drugs such as peptide and proteins. The absorption promoter systems selected for discussion in this review are those with the most promising preclinical and/or clinical data and sufficient toxicology data and/or company development efforts to warrant use in marketed products i.e. CPE-215® (cyclopenta decalactone (azone)) developed by CPEX Pharma, Intravail® (alkylsaccharides) developed by Aegis Therapeutics, ChiSysTM (chitosan) and PecSysTM (low methylated pectin) in development by Archimedes Pharma and CriticalSorbTM (polyglycol mono- and diesters of 12-hydroxystearate (70%), polyethylene glycol (30%)) developed by Critical Pharmaceuticals. Display omitted