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Effects of Fostamatinib on the Pharmacokinetics of the CYP2C8 Substrate Pioglitazone: Results From In Vitro and Phase 1 Clinical Studies
Author(s) -
Martin Paul,
Gillen Michael,
Millson David,
Oliver Stuart,
Brealey Clive,
Surry Dominic,
Sweeny David,
Lau David,
Leese Philip
Publication year - 2016
Publication title -
clinical pharmacology in drug development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.711
H-Index - 22
eISSN - 2160-7648
pISSN - 2160-763X
DOI - 10.1002/cpdd.243
Subject(s) - pioglitazone , medicine , pharmacology , pharmacokinetics , metabolite , thiazolidinedione , cyp2c8 , active metabolite , endocrinology , cytochrome p450 , type 2 diabetes , diabetes mellitus , cyp2c9 , metabolism
Fostamatinib is a prodrug that undergoes gastrointestinal tract dephosphorylation to form the active metabolite, R406. Here we report its cytochrome P450–inducing potential. In vitro, R406 3 and 10 μM induced CYP2C8 to levels representing 53% and 75%, respectively, of the level achieved by the positive control, rifampicin. Induction of other enzymes was minor. The effect of fostamatinib (100 mg twice daily) on the pharmacokinetics of a single oral 30‐mg dose of the CYP2C8 substrate pioglitazone and its metabolite, hydroxy pioglitazone, was then investigated (open‐label, nonrandomized, 2‐period phase I study [n = 15]). Coadministration of fostamatinib and pioglitazone (vs pioglitazone alone) was associated with lower mean maximum plasma concentration values for pioglitazone (geometric least‐squares mean ratio, 82.8; 90% confidence interval, 64.2–106.8) and hydroxy pioglitazone (90.9; 78.6–105.1), an increase in pioglitazone AUC (117.8; 108.4–128.0), a decrease in hydroxy pioglitazone AUC (0–t) (89.7; 78.9–101.9), and an increase in pioglitazone geometric mean t 1/2λz (9.4–12.8 hours). No tolerability concerns were identified upon coadministration. These data suggest that although clinical significance has not been formally evaluated, fostamatinib is unlikely to have a clinically significant effect on the pharmacokinetics of pioglitazone (which may be extrapolated to other CYP2C8 substrates). However, vigilance is advised should these agents be prescribed together.