Stereoisomer

Molecules that share the same molecular formula and connectivity of atoms but differ in the three-dimensional spatial arrangement of those atoms. Stereoisomers include enantiomers (mirror images) and diastereomers (non-mirror-image stereoisomers). The spatial configuration of a drug molecule critically influences its interaction with chiral biological targets such as enzymes and receptors.

Exemplos

• Ibuprofen: S-(+)-enantiomer is the active anti-inflammatory form
• Thalidomide: R-enantiomer is sedative, S-enantiomer is teratogenic
• Cis- and trans-platinum complexes: cisplatin is anticancer, transplatin is inactive