Sulfation

A conjugation reaction that involves adding a sulphate group to a suitable functional group on a drug or a phase I metabolite. Reactions are catalysed by sulfotransferase enzymes found mainly in liver. Different sulfotransferases recognise different classes of substrates; alcohols, phenols, arylamines and steroids. At lower drug concentrations (such as during the early stages of a repeated dosing regimen), sulfation tends to predominate over glucuronidation.

Sulphates formed in the liver are usually transported out of the hepatocyte by ATP-binding cassette (ABC) transporters, either into the bile or into the bloodstream prior to renal elimination.