Zopiclone
Zopiclone was developed and first introduced in 1986 by Rhône-Poulenc S.A., now part of Sanofi-Aventis, the main worldwide manufacturer. Initially, it was promoted as an improvement on benzodiazepines, but a recent meta-analysis found it was no better than benzodiazepines in any of the aspects assessed. On April 4, 2005, the U.S. Drug Enforcement Administration listed zopiclone under schedule IV, due to evidence that the drug has addictive properties similar to benzodiazepines.
Adenosine diphosphate receptor inhibitor
When ticlopidine and clopidogrel were first brought to the market, ticlodipine in 1978 and clopidogrel in 1998, the mechanism of action of these two major antithrombotic drugs was not fully understood. What had been shown was that they were potent inhibitors of ADP-induced platelet aggregation, but the P2Y receptor had not been identified. Furthermore, it was clear that ticlopidine and clopidogrel were prodrugs which means they are inactive in-vitro and therefore need metabolism to be activated in-vivo. It wasn't until the year 2000 when the active metabolites of these drugs were isolated and characterized. About one year later the P2Y platelet receptor for ADP was identified. Following these discoveries the active metabolites and the enzymes responsible for their formation were progressively identified. Thus it was more than 30 years later after the discovery of ticlopidine, and more than 10 years later after the discovery of clopidogrel the mechanism of action of these two drugs was explained.