Table 3: Major ABC drug efflux transporters, their placental localization, and substrates.

TransporterGenePlacental localizationGestational-age-dependent regulationSubstrateInhibitorInducer

P-gpABCB1Apical, syncytiotrophoblastYesDigoxin, fexofenadine, indinavir, vincristine, colchicines, topotecan, paclitaxel, talinolol, loperamideRitonavir, cyclosporine, verapamil, erythromycin, ketoconazole, itraconazole, quinidine, elacridar, azithromycin, valspodarRifampin, St. John’s wort

MRP1ABCC1Basolateral, syncytiotrophoblast predominantly at fetal blood endotheliaYesAdriamycin, topotecan, cisplatinum, methotrexate, etoposide, vincristineProbenecid, sulfinpyrazone, indomethacin, glibenclamide, agosterol A, verapamil, cyclosporin A, genistein, quercetin, RU486, budesonide, agosterol A

MRP2ABCC2Apical, syncytiotrophoblastYesVincristine, etoposide, doxorubicin, epirubicin, methotrexate, irinotecan, ampicillin, ceftriaxone, pravastatin, temocaprilat, grepafloxacin, BQ-12, saquinavir, ritonavir, indinavir, 99mTc-SestamibiProbenecid, sulfinpyrazone, benzbromarone, MK571Sulfinpyrazone

MRP3ABCC3Basolateral, syncytiotrophoblast predominantly at fetal blood endotheliaUnknownEtoposide, methotrexate, tenoposide, acetaminophenProbenecid, sulfinpyrazone, benzbromarone, MK571

MRP4ABCC4UnknownUnknownAzidothymidine monophosphate, lamivudine, ganciclovir, 6-mercaptopurine, 6-thioguanine, methotrexateProbenecid, benzbromarone, sulfinpyrazone, MK571, dipyridamole

MRP5ABCC5Preferentially basolateral, syncytiotrophoblast, and fetal vesselsYesBenzbromarone, sulfinpyrazone, MK571, dipyridamoleSildenafil

MRP6ABCC6UnknownUnknownConjugated organic anions

MRP7ABCC10UknownUnknownOrganic anions

BCRPABCG2Apical syncytiotrophoblastYesDaunorubicin, doxorubicin, topotecan, rosuvastatin, AZT, lamivudineElacridar, acridone carboxamide, fumitremorgin C

OCT3SLC22A3 Basal syncytiotrophoblastCimetidineDesipramine, phenoxybenzamine, quinine

OCTN1SLC22A4Apical syncytiotrophoblastQuinidine, verapamil

References: [6769].