Pharmacology for Anaesthesia and Intensive Care

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5 Isomerism

Enantiopure preparations

There may be advantages in selecting the more desirable moiety from a racemic

mixture and producing it as a single isomer, known as an enantiopure preparation.

The amide local anaesthetics of the mepivacaine series have enantiomeric forms.

The R-form has a more toxic profile than the S-form so that both ropivacaine and

bupivacaine are now available as enantiopure preparations – S-ropivacaine and S-

bupivacaine. Other enantiopure preparations such as S-ketamine, dexketoprofen

and dexmedetomidine are also available.