The formation of an enantiopure drug results from the separation of the enantiomers of a chiral drug. This separation was prompted when it was found that each enantiomer of a molecule can have different effects when used in drugs. This is because the body is very chiral selective reacting to each enantiomer differently and therefore producing different pharmaceutical effects. The use of a drug with a single enantiomer makes the drug more effective. Before a drug of a pure enantiomer can be formed, the two enantiomers must first be separated and tested. Three main techniques are used for this separation: capillary gas chromatography, high performance liquid chromatography, and capillary electrophoresis. Other technique such as chiral crystallization, enzyme-based kinetic separation, and enantioselective synthesis are also used.