Table 1:
Transporters Expressed in the Human Placenta and Examples of Substrates
| Transporter name | Alternative names | Localization in the placenta | Change in expression during pregnancy | Substrate(s) |
|---|---|---|---|---|
| P-gp | ABCB1; MDR1 | Syncytiotrophoblast, cytotrophoblast, fetal and maternal endothelium | ↓, ↔ | Dabigatran etexilate, dexamethasone, digoxin, fexofenadine, glyburide, methotrexate, carvedilol, methotrexate, talinolol |
| BCRP | ABCG2; MXR | Syncytiotrophoblast, cytotrophoblast, fetal endothelium | ↓ | glyburide, atorvastatin, rosuvastatin, zidovudine, cimetidine, methotrexate |
| OAT 1 | SLC22A6 | No expression in placenta | NA | beta-lactam antibiotics, non-steroidal antiinflammatory drugs, furodemide, tenofovir |
| OAT2 | SLC22A7 | No expression in placenta | NA | salicylate, furosemide, acyclovir, ganciclovir |
| OAT3 | SLC22A8 | No expression in placenta | NA | beta-lactam antibiotics, cephalosporin antibiotics non-steroidal antiinflammatory drugs, cimetidine, furosemide, methotrexate |
| OAT4 | SLC22A9; SLC22A11 | Syncytiotrophoblast, cytotrophoblast | NA | uric acid, methotrexate |
| OAT 10 | SLC22A13 | Syncytiotrophoblasta | NA | urate |
| OATP-A | OATP1A2; SLCO1A2; SLC21A3 | Trophocytes | ↓ | ciprofloxacin, fexofenadine, glyburide, atorvastatin, pravastatin, rosuvastatin, atenolol, methotrexate, sumatriptan |
| OATP-1B1 | SLCO1B1 ; OATP-C; HBLRR; LST1; SLC21A6 | Trophoblast | ↓ | bile acid, enalapril, cefazolin, atorvastatin, pravastatin, rosuvastatin, methotrexate, glyburide, fexofenadine |
| OATP-2B1 | OATP-B; SLC21A9 | Syncytiotrophoblast, cytotrophoblast | ↓ | atorvastatin, pravastatin, rosuvastatin, glyburide, fexofenadine, sumatriptan, methotrexate |
| OATP-D | SLCO3A1 ; OATP3A1; SLC21A11 | NA | ↓ | thyroxine, vasopressin |
| OATP-E | SLCO4A1; OATP4A1; OATP1; OATPE; OATPRP1; SLC21A12 | Syncytiotrophoblast | ↔ | benzylpenicillin, thyroxine |
| OATP-8 | SLC21A8 | NA | NA | bile acid |
| MRP1 | ABCC1 | Syncytiotrophoblast, fetal endothelium | ↔ | Ritonavir, methotrexate |
| MRP2 | ABCC2, CMRP, CMOAT | Syncytiotrophoblast | ↑ | atenolol, carvedilol, pravastatin, methotrexate |
| MRP3 | ABCC3 | Syncytiotrophoblast | ↔ | methotrexate |
| MRP4 | ABCC4 | Syncytiotrophoblast | NA | tenofovir, methotrexate |
| MRP5 | ABCC5 | Syncytiotrophoblast, fetal endothelium | ↓ | cGMP, methotrexate |
| OCTN1 | SLC22A4 | NA | NA | gabapentin |
| OCTN2 | SLC22A5 | Syncytiotrophoblast, fetal endothelium | ↓ | carnitine |
| OCT1 | SLC22A1 | NA | ↔ | Metformin, sumatriptan, atenolol |
| OCT2 | SLC22A2 | NA | ↓ | Atenolol, , metformin, , procainamide |
| OCT3 | SLC22A3; EMT | Syncytiotrophoblast | ↓ | metformin |
| MATE1 | SLC47A1 | Syncytiotrophoblast | ↔ | Atenolol, metformin, ganciclovir, cimetidine, acyclovir |
| MATE2 | SLC47A2 | Syncytiotrophoblast | ↓ | Atenolol, metformin, acyclovir, ganciclovir, cimetidine |
| PMAT | SLC29A4; ENT4 | NA | NA | Metformin, atenolol |
| BSEP | ABCB11 | NA | ↓ | pravastatin, fexofenadine |
| MDR3 | ABCB4 | NA | ↑ | digoxin, ursodiol |
| FIC1 | ATP8B1 | NA | ↓ | phosphatidylserine, phosphatidylethanolamine |
Expression in placenta not detected in all studies
Note: ↑ denotes increasing expression during pregnancy, ↓ denotes decreasing expression during pregnancy and ↔ denotes constant expression during pregnancy
Abbreviations’. ABC: Adenosine triphosphate-binding cassette; ATP8B1: ATPase phospholipid transporting 8B1; BCRP: breast cancer resistance protein; BSEP: Bile salt export pump; CMOAT: Canalicular multispecific organic anion transporter; CMRP: Canalicular multidrug resistance protein; EMT: Extraneuronal monoamine transporter; ENT: Equilibrative nucleoside transporter; FIC: Familial intrahepatic cholestasis; HBLRR: Hyperbilirubinemia, Rotor type; LST: Liver specific transporter; MATE: Multidrug and toxin extrusion; MDR: Multidrug resistance protein; MRP: Multidrug resistance-associated protein; MXR: Multixenobiotic resistance; NA: not available; OAT: Organic anion transporter; OATP: Organic anion transporting polypeptide; OATPRP: Organic anion transporting polypeptide-related protein; OCT: Organic cation transporter; OCTN: Organic cation/carnitine transporter; P-gp: P-glycoprotein; PMAT: Plasma membrane monoamine transporter; SLC: Solute carrier; SLCO: Solute carrier organic anion transporter.