What is the importance of optical isomers in drug treatment?

Costs more: Enables drug companies to charge more for a "new" drug that of course isn't new at all. You notice it's almost always the levo enantiomer.

Isomers: Greetings. Isomers are very important in the pharmacological action of drugs. This means generally how good these medications will work inside our bodies. Often times one isomer is more effective or safer and then it becomes the drug that is developed for human usage. Sometimes one drug (the parent) and the isomers are all active and developed as active medications s/a Claritin (loratadine) and Clarinex.