Enantiomeric interaction in the sulfate conjugation of the beta 2-agonist drug albuterol by the human liver.

Sulfate conjugation of the pure enantiomers of albuterol was compared to that of racemic drug using the 100,000g cytosol of four human livers as the catalyst. Whereas a trend towards a lower Kmapp was seen for sulfation of (-)-compared to (+)-albuterol, there was no enantiomeric difference in Vmaxapp. However, when the sulfation of racemic albuterol was compared to that of its pure enantiomers, there was a marked suppression of the reaction. This was due to a reduction in Vmaxapp by about 75% (p less than 0.01) with no difference in Kmapp. Thus, an enantiomeric interaction occurs in the sulfoconjugation of albuterol, which must be taken into account when evaluating the pharmacokinetics of the individual enantiomers following racemic drug administration.