Grünenthal prohibited the research and manufacture of penicillin by German companies. When the ban was lifted, Grünenthal was the first company to introduce penicillin in the postwar period into the German market. This investment achieved a big financial boost for the company. Chemie Grünenthal synthesized thalidomide in 1954 and acquired a 20-year patent. Soon after obtaining a patent in April 1954, the company started clinical trials, and as early as November 1956, marketed the drug for the treatment of respiratory infections under the trade name Grippex, a combination drug that contained thalidomide, quinine, vitamin C, phenacetin, and acetylsalicylic acid. Researchers at
4-Aminosalicylic acid because aminosalicylic acid inhibits the synthesis of thyroid hormones. Drug interactions include elevated phenytoin levels. When taken with rifampicin, the levels of rifampicin in the blood fall by about half. The U.S. FDA assigned PAS to pregnancy category C, indicating that it is not known whether it will harm an unborn baby. With heat, aminosalicylic acid is decarboxylated to produce CO and 3-aminophenol. PAS has been shown to be a pro-drug and it is incorporated into the folate pathway by dihydropteroate synthase (DHPS) and dihydrofolate synthase (DHFS) to generate a hydroxyl dihydrofolate antimetabolite, which in turn inhibits dihydrofolate reductase (DHFR)