Simple process for the preparation of cetyltrimethylammonium naproxenate (naprocet)

Specifications for cetyltrimethylammonium (CTA) naproxenate (naprocet), the active ingredient of pharmaceutical liquid preparations used as antiseptic−antinflammatory detergents, fix severe limits to the presence of residual inorganic counteranion deriving from the starting CTA salt. A new simple procedure, which avoids ionic exchange chromatography and utilizes CTAHSO4 in place of CTABr and CTACl, exploits the quantitative precipitation of K2SO4 from methanol to yield naprocet in line with such specification requirements.