In an overview, PQ is metabolized via two primary phase I pathways, namely: hydroxylation products derived from CYP-mediated oxidation, especially CYP2D6; and oxidative deamination of the side chain affording the terminal alcohol or carboxylic acid, primarily mediated by MAO-A (though CYP2D6 can also produce the PQ alcohol). In addition, a number of glucuronide conjugates of these phase I metabolites are formed, and an unusual (but not unknown, [26, 27]) carbamoylation/glucuronidation of the parent is observed . CYP2D6-mediated metabolism of PQ is known to produce mono- and dihydroxylated primaquines and their quinone-imine products . In human hepatocytes, a more limited suite of metabolites was observed, with the ring oxidation products quinone-imine m/z 274 and the 4-OH-PQ predominant from (+)-PQ, while the oxidation of the terminal amine was the major metabolic route with (−)-PQ . In addition, the PQ-carbamoyl-glucuronide was exclusively formed from (+)-PQ.