Pharmacokinetics and pharmacodynamics of combination chemotherapy with paclitaxel and epirubicin in breast cancer patients

Romano Danesi, Federico Innocenti, Stefano Fogli, Alessandra Gennari, Editta Baldini, Antonello Di Paolo, Barbara Salvadori, Guido Bocci, Pier Franco Conte, Mario Del Tacca

Research output: Contribution to journalArticle

Abstract

Aims: To investigate the pharmacokinetics and pharmacodynamics of epirubicin and paclitaxel in combination, as well as the effects of paclitaxel and its vehicle Cremophor EL on epirubicin metabolism. Methods: Twenty-seven female patients with metastatic breast cancer received epirubicin 90 mg m-2 i.v. followed 15 min or 30 h later by a 3 h i.v. infusion of paclitaxel 175, 200 and 225 mg m-2. Plasma concentrations of paclitaxel, epirubicin and epirubicinol were measured and the relationship between neutropenia and drug pharmacokinetics was evaluated using a sigmoid maximum effect (Emax) model. Finally, the influence of paclitaxel and Cremophor EL on epirubicin metabolism by whole blood was examined. Results: An increase in epirubicinol plasma concentrations occurred after the start of the paclitaxel infusion, resulting in a significant increase in the area under the plasma concentration-time curve (AUC) of epirubicinol (+0.5 μmol l-1 h [95% CI for the difference: 0.29, 0.71], +0.66 μmol l-1 h [95% CI for the difference: 0.47, 0.85] and +0.82 μmol l-1 h [95% CI for the difference: 0.53, 1.11] at paclitaxel doses of 175, 200 and 225 mg m-2, respectively), compared with epirubicin followed by paclitaxel 30 h later (0.61±0.1 μmol l-1 h). A significant increase in epirubicin AUC (+0.74 μmol l-1 h [95% CI for the difference: 0.14, 1.34] and +1.09 μmol l-1 h [95% CI for the difference: 0.44, 1.74]) and decrease in drug clearance (CLTB) (-25.35 l h-1 m-2 [95% CI for the difference: -50.18, -0.52] and -35.9 l h-1 m-2 [95% CI for the difference -63,4,-8,36]) occurred in combination with paclitaxel 200 and 225 mg m-2 with respect to the AUC (3.16±0.6 μmol l-1 h) and CLTB (74.4±28.4 l h-1 m-2) of epirubicin followed by paclitaxel 30 h later. An Emax relationship was observed between neutropaenia and the time over which paclitaxel plasma concentrations were equal to or greater than 0.1 μmol l-1 (tC0.1). The tC0.1 value predicted to yield a 50% decrease in neutrophil count was 7.7 h. Finally, Cremophor EL markedly inhibited the metabolism of epirubicin to epirubicinol in whole blood. Conclusions: Paclitaxel/Cremophor EL affects the disposition of epirubicinol and epirubicin. Furthermore, the slope factor of the Emax relationship between neutropenia and tC0.1 of paclitaxel suggests that the drugs might also interact at the pharmacodynamic level.

Original languageEnglish
Pages (from-to)508-518
Number of pages11
JournalBritish Journal of Clinical Pharmacology
Volume53
Issue number5
DOIs
Publication statusPublished - 2002

Keywords

  • Drug interaction
  • Epirubicin
  • Metabolism
  • Paclitaxel
  • Pharmacodynamics
  • Pharmacokinetics

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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