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Gunshot residue


Why stereoisomers matter in medicine

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Ketamine is a powerful anaesthetic and antidepressant drug. It is also a Class B controlled substance in the UK, has hallucinogenic and dissociative properties, and is highly addictive. How can we maximise the medicinal benefits of ketamine, while minimising the risks? The answer lies in a property of ketamine called stereoisomerism.

Stereoisomers are molecules with the same molecular formula, but a different arrangement of atoms in three-dimensional space. This slight difference can have drastic effects on the behaviour of one stereoisomer compared with another. Ketamine has two stereoisomers, (R)-ketamine and (S)-ketamine (Figure 1). They are enantiomers — stereoisomers that are non-superimposable mirror images of each other, due to ketamine having an asymmetric carbon in its structure. An asymmetric carbon is a carbon with four different groups attached, also referred to as a chiral carbon.

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Gunshot residue

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