Paracetamol was then quickly discarded in favor of phenacetin. These included acetanilide, phenacetin, and paracetamol (acetaminophen). However, those subjected to additional injury from phenacetin or paracetamol may progress to analgesic nephropathy. Kast was instrumental in introducing phenacetin and the sulphonal group of drugs into medicine. How phenacetin and other analgesics lead to this damage is incompletely understood. The sales of phenacetin established Bayer as a leading pharmaceutical company. The phenacetin was removed from Bex in 1975. It is unclear how phenacetin induces injury to the kidney. Von Mering claimed that, unlike phenacetin, paracetamol had a slight tendency to produce methemoglobinemia. Prior to World War One, Britain imported phenacetin from Germany. Bayer chemists soon developed Phenacetin, followed by the sedatives Sulfonal and Trional.