PurposeTwo phase I, open-label trials in healthy subjects assessed whether co-administration with CYP3A4/CYP2C19 inhibitors, itraconazole/fluconazole (study A), or CYP3A4 inducer, rifampicin (study B), affects the exposure, safety/tolerability and pharmacokinetics of selumetinib and its metabolite N-desmethyl selumetinib.MethodsIn study A (n = 26), subjects received a single dose of selumetinib 25 mg and, after 4 days of washout, were randomized to treatment 1 (itraconazole 200 mg twice daily on days 1–11) or treatment 2 (fluconazole 400 mg on day 1 then 200 mg/day on days 2–11) plus co-administration of single-dose selumetinib 25 mg on day 8 (selumetinib staggered 4 h after itraconazole/fluconazole dose); Twenty-one days after discharge/washout, subjects received the alternate treatment. In study B (n = 22), subjects received a single dose of selumetinib 75 mg (day 1) then rifampicin 600 mg/day (days 4–14) plus a single dose of selumetinib 75 mg on day 12. Pharmacokinetic analysis and safety assessments were performed.ResultsSelumetinib co-administered with itraconazole, fluconazole (selumetinib staggered 4 h after itraconazole/fluconazole dose), or rifampicin was well tolerated. Selumetinib exposure was higher when co-administered with itraconazole or fluconazole (area under the plasma concentration-time curve (AUC) increased by 49 and 53%, respectively; maximum plasma concentration (C max) increased by 19 and 26%, respectively) but lower when co-dosed with rifampicin (AUC and C max decreased by 51 and 26%, respectively) versus selumetinib dosed alone. Co-administration with itraconazole or rifampicin decreased N-desmethyl selumetinib AUC(0–t) (11 and 55%, respectively), and C max (25 and 18%, respectively), with fluconazole, AUC(0–t) increased by 40%, but there was no effect on C max.ConclusionsCo-administration of CYP3A4/CYP2C19 inhibitors will likely increase exposure to selumetinib, while CYP3A4 inducers will likely reduce its exposure.Electronic supplementary materialThe online version of this article (doi:10.1007/s00228-016-2153-7) contains supplementary material, which is available to authorized users.
Background and objectivesFostamatinib is a spleen tyrosine kinase inhibitor that has been investigated as therapy for rheumatoid arthritis and immune thrombocytopenic purpura. The present studies assessed the potential for pharmacokinetic interaction between fostamatinib and the commonly prescribed medications oral contraceptive (OC), warfarin, and statins (rosuvastatin, simvastatin) in healthy subjects.MethodsThe OC study was a crossover study over two 28-day treatment periods (Microgynon® 30 plus placebo or fostamatinib). Concentrations of OC constituents (ethinyl estradiol/levonorgestrel) were measured. Effects on warfarin pharmacokinetics and pharmacodynamics were assessed (21-day study). Warfarin was administered on days 1 and 14, fostamatinib on days 8–20. The statin study was a two-period, fixed-sequence study of the effects of fostamatinib on exposure to rosuvastatin or simvastatin (single doses). Safety was assessed throughout.ResultsFostamatinib co-administration with OC increased exposure to ethinyl estradiol [area under the plasma concentration–time curve at steady state (AUCss) 28 % [confidence interval (CI 90 %) 21–36]; maximum plasma concentration (Cmax) at steady state (Cmax,ss) 34 % (CI 26–43)], but not levonorgestrel (AUCss 5 %; Cmax,ss −3 %), while exposure to luteinizing hormone and follicle-stimulating hormone decreased (≈20 %). Fostamatinib did not affect the pharmacokinetics/pharmacodynamics of warfarin to a clinically relevant extent, but caused an upward trend in AUC for both R- and S-warfarin [18 % (CI 13–23) and 13 % (CI 7–19)]. Fostamatinib increased rosuvastatin AUC by 96 % (CI 78–115) and Cmax by 88 % (CI 69–110), and increased simvastatin acid AUC by 74 % (CI 50–102) and Cmax by 83 % (CI 57–113).ConclusionFostamatinib exhibits drug–drug interactions when co-administered with OC, simvastatin, or rosuvastatin, with the AUC of statins almost doubling. Fostamatinib did not exhibit a clinically relevant DDI on warfarin.Electronic supplementary materialThe online version of this article (doi:10.1007/s40268-015-0120-x) contains supplementary material, which is available to authorized users.
Two phase I open‐label studies were conducted to investigate the pharmacokinetics (PK), safety, and tolerability of single oral doses of selumetinib in subjects with end‐stage renal disease (ESRD) undergoing hemodialysis and subjects with varying degrees of hepatic impairment; both studies included a matched control group comprised of healthy individuals. In the renal impairment study, subjects received single doses of selumetinib 50 mg; those with ESRD received selumetinib before and after dialysis (with a between‐treatment washout period of ≥7 days). In the hepatic impairment study, subjects received varying single doses of selumetinib (20‐50 mg) depending on liver dysfunction (mild, moderate, or severe as per Child‐Pugh classification). PK, safety, and tolerability data were collected from both studies. Overall, 24 subjects were included in the renal impairment study (ESRD, N = 12; healthy subjects, N = 12). Selumetinib exposure (AUC and Cmax) was not increased in the ESRD group vs healthy subjects. Selumetinib exposure was lower when selumetinib was dosed before vs after dialysis, although individual exposure was variable. Overall, 32 subjects were included in the hepatic impairment study (mild, moderate, and severe impairment, N = 8 per group; healthy subjects, N = 8). Generally, dose‐normalized total selumetinib exposure was increased by 25% to 59% in subjects with moderate and severe hepatic impairment compared with healthy subjects. Increasing Child‐Pugh score, decreasing serum albumin, and increasing prothrombin time correlated with increasing unbound selumetinib exposure. In both studies, selumetinib was well tolerated with no new safety concerns. These studies will inform dose adjustment considerations in patients.
Robust and sensitive LC-MS/MS assays for the quantification of selumetinib and two of its metabolites were validated in human biological matrices and are being used to support the clinical development program.
Aim: Mass-selective quantitation is a powerful attribute of LC–MS as a platform for bioanalysis. Here, a sensitive LC–MS approach has been validated for an oligonucleotide having chemical modifications (e.g., N-acetylgalactosamine [GalNAc] conjugated), to distinguish between the conjugated and unconjugated forms of the oligonucleotide, thereby enabling a nuanced view of the pharmacokinetic profile. Results: A high-sensitivity methodology for mass-specific measurement of AZD8233, a GalNAc-conjugated 16-mer oligonucleotide, using LLE-SPE with optimized LC conditions and detection of a low-mass fragment ion was successfully validated in the range of 0.20–100 ng/ml in human plasma. Conclusion: The AZD8233 LC–MS methodology adds valuable insight on the GalNAc linker’s in vivo stability to the program and should be broadly applicable to oligonucleotides requiring high sensitivity and mass-selective measurement for quantitative discrimination from metabolites and endogenous interferences.
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