What would you think if I gave you a drug and said this is going to help you but I want you to know ahead of time that 50% of the dose is not affected, in fact the drug is 50% not pure. The idea of that would make you feel you want another drug. The reality of that is that a large # of drugs we give are 50% impure and the reason is b/c so many drugs we give are racemic mixtures, a 50:50 mixture of enantiomers. Most drugs that demonstrate optical activity only one isomer is pharmalogically active, so what that means is that we are giving a product where 50% of it is inactive. There are some important considerations you have to take into account when you have drugs that are optically active and what we would like to do today is take the things we have gone thru this semester where we have really ignored stereochemistry thru that whole process and talk about the times in which you need to consider aspects of stereochemistry. This has become a big issue now the FDA has pushed for drug companies to be able to characterize both isomers when giving a racemic mixture, also to force manufactures to only market the active isomer and not going with the standard practice of giving a drug which is only 50% pure. There are also some drugs on the market as racemic mixtures that now compounds are being introduced as enantiomers and therefore this results in different doses because now you are giving a drug which is 100% active.
             Stereochemistry has long been recognized, Louis Pasteur was probably the 1st to state the significance of it , he said most natural organic products, the essential products of life are asymmetric... This established perhaps the only well marketed line of demarcation that can at present be drawn between the chemistry of dead matter and the chemistry of living matter. What he was trying to say is that basically the chemistry of life is highly dependent on geometric form and as a consequence stereochemistry is essential...