Interaction of thiazolidinediones (glitazones) with the ATP-binding cassette transporters P-glycoprotein and breast cancer resistance protein.
OBJECTIVE
Thiazolidinediones (glitazones) are frequently prescribed antidiabetic drugs commonly used in combination drug regimens. To evaluate the risk of drug-drug interactions, we therefore aimed to systematically investigate the inhibitory and inductive effects of all glitazones on 2 of the most relevant drug transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), in vitro.


METHODS
The inhibition of P-gp and BCRP was assessed by fluorometric assays quantifying the increase in the intracellular concentration of fluorescent P-gp or BCRP substrates caused by their combination with the glitazones. The induction of mRNA expression was quantified by real-time RT-PCR after the treatment of HuH-7 cells with the respective compounds for 4 days.


RESULTS
Rosiglitazone and troglitazone significantly inhibited P-gp and BCRP function and induced mRNA expression of BCRP but not of P-gp. Pioglitazone, which exhibited very low solubility, could only be tested up to 0.5 micromol/l and did not provoke an effect in any of the assays.


CONCLUSIONS
After comparison of the in vitro data and published clinical studies, it seems unlikely that the inhibition of BCRP and P-gp by rosiglitazone plays a role in the clinical situation. In contrast, BCRP induction by rosiglitazone might be of relevance in vivo, but has to be verified in dedicated clinical studies.
Department of Internal Medicine VI, Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, DE-69120 Heidelberg, Germany. johanna.weiss@med.uni-heidelberg.de
Johanna
J
Weiss
Alexandra
A
Sauer
Melanie
M
Herzog
Rainer H
RH
Böger
Walter E
WE
Haefeli
Ralf A
RA
Benndorf
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D005470:Fluorometry; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D045162:Thiazolidinediones / Q000494:pharmacology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; C501412:Abcg2 protein, mouse; D007004:Hypoglycemic Agents; D012333:RNA, Messenger; D045162:Thiazolidinediones