TY - JOUR
T1 - Pharmacokinetics and pharmacodynamics of combination chemotherapy with paclitaxel and epirubicin in breast cancer patients
AU - Danesi, Romano
AU - Innocenti, Federico
AU - Fogli, Stefano
AU - Gennari, Alessandra
AU - Baldini, Editta
AU - Di Paolo, Antonello
AU - Salvadori, Barbara
AU - Bocci, Guido
AU - Conte, Pier Franco
AU - Del Tacca, Mario
PY - 2002
Y1 - 2002
N2 - 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.
AB - 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.
KW - Drug interaction
KW - Epirubicin
KW - Metabolism
KW - Paclitaxel
KW - Pharmacodynamics
KW - Pharmacokinetics
UR - http://www.scopus.com/inward/record.url?scp=0035999644&partnerID=8YFLogxK
U2 - 10.1046/j.1365-2125.2002.01579.x
DO - 10.1046/j.1365-2125.2002.01579.x
M3 - Article
SN - 0306-5251
VL - 53
SP - 508
EP - 518
JO - British Journal of Clinical Pharmacology
JF - British Journal of Clinical Pharmacology
IS - 5
ER -