Baxter Oncology


Interactions between Cyclophosphamide and Ondansetron

The pharmacokinetics of high-dose cyclophosphamide (as well as cisplatin and carmustine) were compared in 23 patients who received ondansetron and in 129 patients who received prochlorperazine as an antiemetic; all patients also received lorazepam and diphenhydramine. The mean AUCs for cyclophosphamide (and cisplatin, but not carmustine) were significantly lower in ondansetron, compared with prochlorperazine, recipients (Cagnoni et al). As admitted by the investigators, the small sample size and heterogeneity of the group of patients precludes any outcome analysis of pharmacodynamic endpoints. Lower AUCs for cyclophosphamide when combined with ondansetron were confirmed in a second study with 54 breast cancer patients who were treated with high-dose cyclophosphamide, cisplatin, and carmustine as well. Antiemetic therapy consisted of continuous infusion of ondansetron with or without prochlorperazine, or, in a historical control group, of prochlorperazine with lorazepam (Gilbert et al).
Contrasting results showing no effect of ondansetron on the activation or inactivation of conventionally dosed cyclophosphamide (600 mg/m²) come from a third investigation (Lorenz et al).

References
Cagnoni PJ et al
Modification of the pharmacokinetics of high-dose cyclophosphamide and cisplatin by antiemetics.
Bone Marrow Transplant 1999; 24: 1-4

Gilbert CJ et al
Pharmacokinetic interaction between ondansetron and cyclophosphamide during high-dose chemotherapy for breast cancer.
Cancer Chemother Pharmacol 1998; 42: 497-503

Lorenz C et al
Hat Ondansetron einen Einfluß auf die Pharmakokinetik von Cyclophosphamid?
Krankenhauspharmazie 2000; 21: 374-375
© 2001 Baxter Oncology