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 most common contemporary formulation), among others. Depending on the version, additional amounts of the substances and additional active ingredients (e.g. saffron, sugar, eugenol) are added, modifying its effects (e.g., amount of sedation, or anti-tussive properties). There is probably no single reference that lists all the pharmaceutical variations of laudanum that were created and used in different countries during centuries since it was initially formulated. The reasons are that in addition to official variations described in pharmacoepias, pharmacists and drug manufacturers were free to alter such formulas. The alcohol content of Laudanum probably varied substantially; on the labels of turn-of-the-century bottles