Didanosine was developed by Bristol-Myers Squibb in collaboration with the NIH for the treatment of HIV-1 infections. Upon administration the drug is metabolized to the active metabolite which inhibits HIV-1 reverse transcriptase both by competing with deoxyadenosine 5'-triphosphate and by its incorporation into viral DNA. Didanosine was approved by FDA under the name Videx (among the other names).

Methapyrilene is an antihistamine and anticholinergic of the pyridine chemical class which was developed in the early 1950s. It was sold under the trade names Co-Pyronil and Histadyl EC. It has relatively strong sedative effects, to the extent that its primary use was as a medication for insomnia rather than for its antihistamine action. Together with scopolamine, it was the main ingredient in Sominex, Nytol, and Sleep-Eze. It also provided the sedative component of Excedrin PM. Manufacturers voluntarily withdrew methapyrilineb drug products from the market in May and June 1979, when methapyrilene was demonstrated to cause liver cancer in rats when given chronically.