Patent medicine the patent medicines, some of their makers began replacing the opium tincture laudanum with acetanilide, a particularly toxic non-steroidal anti-inflammatory drug with analgesic as well as antipyretic properties that had been introduced into medical practice under the name "Antifebrin" by A. Cahn and P. Hepp in 1886. But this ingredient change probably killed more of the nostrum's users than the original narcotics did, since acetanilide not only caused an alarming cyanosis due to methemoglobinemia but was later discovered to cause liver and kidney damage. The occasional reports of acetanilide-induced cyanosis prompted the search for supposedly less toxic aniline derivatives, such
Laudanum other such drugs continued to be legally available without prescription as long as they were labeled. It is estimated that sale of patent medicines containing opiates decreased by 33% after labeling was mandated. In 1906 in Britain and in 1908 in Canada "laws requiring disclosure of ingredients and limitation of narcotic content were instituted". The Harrison Narcotics Tax Act of 1914 restricted the manufacture and distribution of opiates, including laudanum, and coca derivatives in the US. This was followed by France's "" in 1916, and Britain's Dangerous Drugs Act in 1920. Laudanum was supplied to druggists and physicians in regular