In addition to the plasma levels of the two parent drugs, patterns of metabolism of resveratrol and pterostilbene were also compared. Glucuronide and sulfate conjugates were the primary metabolites of both agents; resveratrol was not detectable after pterostilbene administration. For both agents, sulfate conjugation was generally more extensive than was glucuronidation; an exception to this general pattern was seen with administration of the low dose of resveratrol, after which levels of sulfate and glucuronide conjugates were similar (Tables 4, ,5,5, ,66).