1. Arsenicals, mainly Arsphenamine, neoArsphenamine, acetarsone and mapharside, in combination with bismuth or mercury then became the mainstay of

2. As nouns the difference between Arsphenamine and neoArsphenamine is that Arsphenamine is (pharmaceutical drugorganic compound) a phenolic amine derivative of arsenic that was used to treat syphilis (under the trade name of salvarsan) while neoArsphenamine is a derivative of Arsphenamine once used to treat syphilis and yaws.