The effect of atovaquone on etoposide pharmacokinetics in children with acute lymphoblastic leukemia

Matthijs E.C. Van De Poll, Mary V. Relling, Erin G. Schuetz, Patricia L. Harrison, Walter Hughes, Patricia M. Flynn

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: The use of trimethoprim/sulfamethoxazole in the prevention of Pneumocystis carinii pneumonia in patients with acute lymphoblastic leukemia (ALL) may cause undesirable adverse effects: fungal overgrowth, neutropenia, and drug resistance. A possible alternative is atovaquone, a hydroxynaphthoquinone with anti-Pneumocystis carinii activity. However, it is not known if atovaquone alters the disposition or adverse effects of antileukemic drugs. Methods: Using a crossover study design, we compared the pharmaco-kinetics of etoposide and its CYP3A4-formed catechol metabolite when given as a 300 mg/m2 i.v. infusion following daily atovaquone versus trimethoprim/sulfamethoxazole in nine patients. Results: The area under the concentration time curve (AUC) of etoposide, etoposide catechol and the catechol to etoposide AUC ratio were slightly higher (a median of 8.6%, 28.4%, and 25.9%) following atovaquone as compared to trimethoprim/sulfamethoxazole (P=0.055, P=0.031 and P=0.023), respectively. In vitro analysis in human liver microsomes showed modest inhibition of etoposide catechol formation in the presence of atovaquone. Using uptake of 3H-vinblastine in L-MDR1 cells, atovaquone was shown to inhibit P-glycoprotein with an apparent Ki of 95.6 μM. Conclusions: Although the effect of atovaquone on etoposide disposition was modest, in light of the fact that the risk of etoposide-related secondary acute myeloid leukemia has been linked to minor changes in schedule and concurrent therapy, we suggest caution with the simultaneous administration of atovaquone and etoposide, particularly if used with other CYP3A4/P-glycoprotein substrates.

Original languageEnglish (US)
Pages (from-to)467-472
Number of pages6
JournalCancer Chemotherapy and Pharmacology
Volume47
Issue number6
DOIs
StatePublished - 2001

Keywords

  • Atovaquone
  • CYP3A4
  • Cotrimoxazole
  • Etoposide
  • P-glycoprotein

ASJC Scopus subject areas

  • Oncology
  • Toxicology
  • Pharmacology
  • Cancer Research
  • Pharmacology (medical)

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