The study test whether the NSAID allosteric site of human sulfotransferase 1A1 (SULT1A1) is
operative in humans. The study will test the effects of mefenamic acid (MEF) on the
sulfonation of acetaminophen (APAP, a SULT1A1 specific substrate) and dehydroepiandrosterone
(DHEA, a SULT2A1 substrate). If the allosteric site is active in vivo, MEF is predicted to
result in a decrease in sulfonation of APAP (MEF inhibits SULT with high affinity (Ki = 23
nM), and to have no effect on sulfonation of the DHEA (MEF has little or no effect on SULT2A1
activity).