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Analytical requirements , Chirality

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  254

2026-10-19

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Analytical requirements

Chirality

The question of stereoselective analyses for ther apeutic drugs has attracted increasing attention in recent years. Many pharmacologically active compounds contain a carbon atom linked to four different substituents, and thus have the potential to exist in two different isomeric forms. This property is called chirality, and the pairs of mirror-image compounds are termed stereoisomers (or enantiomers). Frequently, only one stereoisomer possesses a particular pharma cological action, and the other may be inactive or active in a different way. For example, the D-isomer of propoxyphene is a narcotic analgesic, while the L-isomer has no narcotic proper ties and is used as a cough suppressant. Stereoisomers may also show marked differences in pharmacokinetic properties such as clearance and volume of distribution, and stereospecific analytical methods able to resolve individual isomers are required if meaningful TDM information is to be obtained. These methods rely on HPLC. Immunoassays are of little use because it is difficult to produce anti bodies that react to the different isomers in a way that exactly reflects their biological activity.