Thus, among the interactions of both proteins with (−) or (+)CLA at higher oral doses (e. g. a single dose of 160 mg/kg for rats), CYP3A may play a more important role than P-gp in the absorption and metabolic elimination of CLA enantiomers, which explains their stereoselective differences in three target tissues of the brain and plasma concentrations at 8 h and 12 h after dosing respectively[16,18], and provides useful information to the clinical pharmacology of (−)CLA as a candidate drug for treatment of Alzheimer’s disease. The gene discussed is CYP3A4; the disease is Alzheimer disease.