Liver enzymes: in a 144-week clinical study (GS-01-934), elevations of aspartate aminotransferase (AST > 5 times ULN (upper limit of normal)) and of alanine aminotransferase (ALT > 5 times ULN) were reported in 3% and 2% of patients treated with efavirenz, emtricitabine, and tenofovir disoproxil fumarate (n=257) and 3% and 3% of patients treated with efavirenz and fixed-dose zidovudine/ lamivudine (n=254), respectively.