Pharmacokinetic Assessment of Multiple ATP-binding Cassette Transporters: The Power of Combination Knockout Mice

Table 1.

ABC Transporter Functions as Determined from Combination Knockout Mice

Findings
Combination Knockout Substrate Transporter Function References
Abcb1a −/− /Abcb1b −/− /Abcc1 −/− Etoposide P-gp restricts brain penetration (5, 6)
Abcc1 limits accumulation in the cerebrospinal fluid
P-gp and Abcc1 protect against etoposide-induced toxicity
Abcb1a −/− /Abcb1b −/− /Abcg2 −/− Topotecan P-gp mediates elimination and restricts brain penetration (40)
Abcg2 limits oral uptake and mediates elimination
Abcg2 restricts brain penetration when P-gp is absent
Imatinib P-gp mediates fecal excretion and restricts brain penetration (42)
Abcg2 has minor impact on fecal excretion; partially limits brain penetration when P-gp is absent
Lapatinib P-gp restricts brain penetration (43)
Abcg2 partially restricts brain penetration when P-gp is absent
Dasatinib P-gp limits oral availability and restricts brain penetration (44)
Abcg2 partially restricts brain penetration when P-gp is absent
Abcb1a −/− /Abcb1b −/− /Abcc2 −/− Doxorubicin P-gp main transporter for biliary excretion (52)
Abcc2 partly compensates for the absence of P-gp
Paclitaxel P-gp limits oral uptake and facilitates direct intestinal excretion (8)
Abcc2 is main transporter for biliary excretion; influences oral pharmacokinetics when P-gp is absent
P-gp and Abcc2 equally affect iv pharmacokinetics
Abcc2−/−/Abcc3−/− and Abcc2−/−/Abcg2−/− Methotrexate Abcc2 is the main transporter for biliary excretion (12, 61)
Abcg2 mediates biliary and urinary excretion when Abcc2 is absent
Abcc3 mediates sinusoidal excretion from the liver when Abcc2 is absent
7-Hydroxy-methotrexate Abcc2 is the main transporter for biliary excretion
Abcg2 mediates biliary and urinary excretion when Abcc2 is absent
Abcc3 mediates sinusoidal excretion from the liver when Abcc2 is absent
Abcc2 −/− /Abcc3 −/− Morphine-3- glucuronide Abcc2 is the main transporter for biliary excretion (11)
Abcc3 mediates sinusoidal excretion from the liver when Abcc2 is absent
Fexofenadine Abcc2 mediates biliary excretion (13)
Abcc3 mediates sinusoidal excretion from the liver

This Article

  1. MI June 2009 vol. 9 no. 3 136-145