Single isomer versus racemate: is there a difference? Clinical comparisons in allergy and gastroenterology.

Many commonly prescribed drugs exist as a mixture of two distinct chiral isomer forms (enantiomers), each with its own unique chemistry, receptor affinity, and pharmacokinetic profile. Much is unknown concerning the clinical utility of these single enantiomers. This review of the stereoisomers of two commonly used drugs--albuterol for asthma and omeprazole for gastroesophageal reflux disease (GERD) and peptic ulcers--examines the improved efficacy, pharmacokinetics, decreased adverse effects, and fewer drug-drug interactions associated with single enantiomers.