Translocates drugs and phospholipids across the membrane (PubMed:2897240, PubMed:35970996, PubMed:8898203, PubMed:9038218, PubMed:35507548). Catalyzes the flop of phospholipids from the cytoplasmic to the exoplasmic leaflet of the apical membrane. Participates mainly to the flop of phosphatidylcholine, phosphatidylethanolamine, beta-D-glucosylceramides and sphingomyelins (PubMed:8898203). Energy-dependent efflux pump responsible for decreased drug accumulation in multidrug-resistant cells (PubMed:2897240, PubMed:35970996, PubMed:9038218). {ECO:0000269|PubMed:2897240, ECO:0000269|PubMed:35507548, ECO:0000269|PubMed:35970996, ECO:0000269|PubMed:8898203, ECO:0000269|PubMed:9038218}. This is the function of ABCB1 (ATP binding cassette subfamily B member 1, Ensembl gene identifier ENSG00000085563).